Glossary

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17-hydroxyprogesterone (17-OHP)This is the chemical that cortisol is made from. Children and adults with congenital adrenal hyperplasia (CAH) have much higher levels of 17-OHP in their blood because they cannot turn it into cortisol. Detecting increased amounts of 17-OHP in the blood is one of the tests that confirm the diagnosis of CAH.

21-hydroxylase (21-OH)This is an enzyme made by the body. It helps make cortisol and aldosterone. The enzyme is found in the adrenal glands and is essential in making the amounts of cortisol and aldosterone needed by the body.
21-hydroxylase deficiency (21-OHD)This is the most common type of inherited enzyme deficiency causing congenital adrenal hyperplasia (CAH). Children who are completely missing this enzyme, or have very little working enzyme, usually have the ‘salt-wasting’ form of classic CAH. Children who have a reduced level of 21-OH but still make some of this enzyme usually have the ‘simple-virilizing’ form of classic CAH.

AcylcarnitineOur bodies break down the fat that we eat into substances called fatty acids. Fatty acids are then broken down even further into substances called acylcarnitines. Acylcarnitines are used to create energy for the body.
Acylcarnitine ProfileThis is a blood test that can be used to diagnose certain fatty acid oxidation and organic acid disorders. Fatty acids get broken down into substances called acylcarnitines. These substances are then used to create energy for the body. Certain fatty acid oxidation disorders cause changes in the usual pattern of acylcarnitines.
Adrenal crisisThis is a life-threatening state in which the body is not making enough cortisol. Babies with classic CAH may have frequent adrenal crises if they are not treated. They are also at risk for adrenal crises during illness or times of stress if their medication is not increased. Symptoms of adrenal crisis include: dizziness, paleness and sweating (if blood sugar is low), abdominal pain, vomiting, low blood pressure, dehydration, confusion, rapid heart beat, and, if not treated, coma and possibly death.
Adrenal glandsThe adrenals are a pair of glands near the kidneys that make three types of hormones important in helping the body function normally. The main hormones made in the adrenal glands are cortisol, aldosterone and sex-hormones such as estrogen, progesterone, and male-like androgens (including testosterone). When the adrenal glands make more or less of one or more of these hormone, health problems occur.
AdrenalsThe adrenals are a pair of glands near the kidneys that make three types of hormones important in helping the body function normally. The main hormones made in the adrenal glands are cortisol, aldosterone and sex-hormones such as estrogen, progesterone, and male-like androgens (including testosterone). When the adrenal glands make more or less of one or more of these hormone, health problems occur.
Affected family memberA family member who has the disease or medical condition in question.
AldosteroneThis is a hormone made in the adrenal glands. It helps the body keep a normal amount of salt and water in the blood. This keeps the blood pressure at a normal level. High levels of aldosterone cause too much salt and water to be kept in the blood and causes high blood pressure. Low levels of aldosterone cause the kidney to remove too much salt and water from the blood and excrete it in the urine. This causes dehydration and low blood pressure. If the blood pressure drops too low, it can cause adrenal crisis and lead to a coma and possibly death.
AlleleName for different forms of a gene. Different alleles of a gene may produce different forms of a protein. Some alleles of a gene may form altered proteins that do not function properly. These can often lead to disease.
Amino acidAmino acids are small molecules that make up proteins. There are over 100 different amino acids, but our body uses only 20 amino acids to make all of its proteins. Our genes determine the sequence of amino acids in a protein. This sequence determines what shape the protein takes, and what function that protein serves in the body.
Amino acid disorders (AAs)These are a group of rare inherited conditions. People with amino acid disorders cannot digest particular amino acids – the building blocks of protein. These amino acids, along with other toxic substances, build up in the body. This can cause serious effects on health, growth, and learning.
Ammonia (NH3)This is a waste product made when protein is broken down for the body to use. Ammonia is harmful to the body. It is usually changed to a harmless substance called “urea.” Urea is then removed from the body in the urine. People with urea cycle disorders cannot get rid of ammonia. If these conditions are not treated, ammonia can build up and cause serious health problems.
AmniocentesisThis is a test done during pregnancy. A needle is used to remove a small sample of fluid from the sac around the fetus. The sample can be used to test for certain genetic disorders in the fetus. Amniocentesis to test for genetic conditions is usually done between 13 and 20 weeks of pregnancy.
AndrogensThis is a group of sex hormones that help create male sex characteristics and masculine traits. Androgens help with normal development of the penis and testicles in male fetuses. At puberty, androgen levels go up and cause secondary male sex characteristics such as facial hair, pubic and underarm hair, growth of the penis, sperm formation, muscle development and growth in height. Girls make androgens, too, but in much smaller amounts than boys.
AnemiaThis is a condition in which the blood has too few red blood cells or too little hemoglobin, the oxygen carrying molecule in the blood. People with anemia are often pale, tired, weak, dizzy and short of breath.
AntibodiesAs part of the immune system, antibodies are found in the blood and help to detect and destroy invaders like bacteria and viruses.
AntigensInvaders of the body that usually trigger an immune response
Arginine (arg)This is one of 20 amino acids that make up protein. It is also known as “Arg.” Most of the arginine needed is made by the body. In most cases, it does not need to be eaten in the diet. Arginine can also be bought in pill form. Children with certain urea cycle disorders are often given arginine supplements. These supplements can help clear the body of ammonia.
AspartameThis is one type of sugar substitute. It is made up of the amino acids phenylalanine (Phe) and aspartic acid (Asp). It is sold under the brand names “Equal,” “Nutrasweet,” “Sweetmate” and “Canderal.” Aspartame is harmful for people with PKU because it causes Phe to build up in the blood. High levels of Phe can cause health problems and brain damage. It is important for people with PKU to avoid any foods or drinks that contain aspartame.
AsymptomaticNot showing any of the signs of the condition or disease.
AtaxiaThis is the lack of ability to coordinate muscle movements. It causes balance problems and difficulty walking. People with ataxia often walk with jerky, unsteady movements. Ataxia has many different causes.
AtrophyA decrease in the size and strength of a muscle
Autosomal dominantGenes come in pairs. If one gene of a pair causes, by itself, a particular trait or disorder to be present, it is called ‘dominant.’ If the gene is found on one of the first 22 pairs of chromosomes, it is called autosomal dominant (chromosomes 1 through 22 are called ‘autosomes’). Although genes are always in pairs, in autosomal dominant inheritance, you only need to inherit one copy of a dominant gene in order to show a particular trait.Autosomal dominant conditions can be inherited from one parent, who also has that condition or the gene for that condition, or can occur in one person in the family for the first time (called a ‘new mutation’). If neither parent has the autosomal dominant gene change that the child has, it is a ‘new mutation’ just present in that child, and there is a low risk for it to affect other siblings. However, the person with the autosomal dominant gene change has a 50% chance to pass it on to each of his or her children.
Autosomal recessiveMost of the metabolic disorders that can be detected by newborn screenings are inherited in an “autosomal recessive” pattern. Autosomal recessive conditions affect both boys and girls equally. How autosomal recessive inheritance works: Everyone has a pair of genes for each enzyme in the body. A separate pair of genes is responsible for making each enzyme. A person with a metabolic disorder has one enzyme that is either missing or not working properly. The problem is caused by a pair of “recessive” genes that are not working correctly. They do not make the needed enzyme. A person has to have two non-working “recessive” genes in order to have an autosomal recessive metabolic disorder. A person with an autosomal recessive disorder inherits one non-working gene from his or her mother and the other from his or her father. The parents are called carriers for that condition. Parents of children with a metabolic disorder rarely have the disorder themselves. Instead, for that pair of genes, each parent has one that is working correctly and one that is not working (called the “recessive” gene). People with a single non-working gene are called carriers. If one gene of the pair is working correctly, it makes up for the recessive non-working gene. Therefore, carriers usually will not have the condition.
AutosomeOne of the two types of chromosomes found in most animals. Autosomes contain many thousands of genes, but do not contain genes that determine the sex of an organism. Sex chromosomes, on the other hand, do contain sex-determining genes. Humans have a total of 46 chromosomes; 44 autosomes (chromosome pairs 1-22) and two sex chromosomes (X and Y).

B cells (also called B-lymphocytes)A type of white blood cell that matures in the bone marrow. B cells make antibodies against antigens and create new B cells that remember the antigens old B cells already encountered.
Base pairBases are the components that make up DNA. There are 4 bases: Adenine (A), Cytosine (C), Guanine (G), and Thymine (T). In a DNA molecule, the bases pair with each other to hold together the two strands in a double strand of DNA. A always pairs with T, and G always pairs with C. Base pairs are also used as a unit of measure to indicate a length of DNA. A piece of DNA that is 10bp long has 10 base pairs in it. Likewise, a gene that is 2Kb long has 2,000 base pairs. The human genome has around 3 billion base pairs.
BenignSomething that is not dangerous to one’s health, or can be cured.
BetaineThis is a vitamin-like substance found in grains and other foods. It can also be bought in pill form. It is sometimes used as a treatment for homocystinuria. It can help lower the amount of homocystine in the blood. It may also help lessen the risk of blood clots in people with this condition.
BicarbonateThis is a substance that lowers the amount of acid in the blood. It is sometimes used as part of the treatment for children with certain organic acid disorders.
Biochemical genetics doctorA doctor or medical geneticist who has special training in diagnosing and treating metabolic disorders. They are often known as Biochemical Geneticists. They often work in university hospitals or large medical centers.
BiopsyThis is a procedure that involves taking a small piece of tissue (like skin) from a person to help diagnose a condition.
BiotinThis is one type of B vitamin. It helps break down fat, protein, and carbohydrates from food for use by the body. Biotin is found in chicken, salmon, cheese, eggs, and some vegetables. It can also be bought in pill form. Children with certain metabolic disorders may be treated with biotin supplements.
Blood relativeEveryone in your family who is genetically related to you. Blood relatives DO NOT include step children, adopted individuals, and people who have married into the family.
Bone ageThis is an estimate of the age, or degree of maturity, of a child’s bones. It is done by taking an X-ray of the wrists and hands and comparing the bone’s development to the average for the child’s chronological age. The test can tell a doctor a child’s remaining growth potential and whether or not the growth plates are closing too early.
Bone marrowBone marrow is the tissue that is located around the hollow center of bones. Bone marrow produces new red blood cells.
Bone marrow transplantWhen a person does not have enough working red blood cells, they may have a bone marrow transplant. In this surgical procedure, bone marrow is removed from another person (donor) and implanted into the patient. The patient and bone marrow donor must be a genetic match. There are many risks associated with bone marrow transplants.
Branched-chain amino acids (BCAA)These are amino acids that have a chemical structure that looks like branches on a tree. Leucine (leu), valine (val), and isoleucine (ile) are three of the BCAAs. They are found in all foods that contain protein. Large amounts are found in meat, eggs, milk, and other dairy foods. Smaller amounts are found in flour, cereal, and in some vegetables and fruits.
BronchiolesThe branching airways that lead from the bronchi to the air sacs (alveoli) deep in the lungs. Bronchioles are 1 millimeter in diameter or less.
BronchitisThis is inflammation (swelling and redness) of the bronchi that causes a persistent cough. People with bronchitis make lots of sputum/mucus. They often have a fever and chest pain, too. Bronchitis is often caused by respiratory infections (viruses or bacteria) or irritants in the air such as tobacco smoke.

Carbamazepinea medication used to treat seizures, convulsions, nerve pain and other conditions
CarbohydrateThis is one of the three types of nutrients in food (carbohydrates, fats, proteins). Sugars and starches are the most important types of carbohydrates. They are broken down by the body into glucose, the main source of energy for the body. Carbohydrates are found in foods such as: bread, cereal, pasta, grains, fruits and vegetables. Milk and dairy products, fruit drinks, sugar, candy, and sweet desserts also contain carbohydrates.
CardiologistA cardiologist is a doctor who specializes in the heart.
CardiomyopathyThis is a condition that causes the heart muscle to become weak and enlarged. These changes make it more difficult for the heart to pump blood. If not treated, it can be life-threatening. Some of the causes include certain metabolic disorders, viruses, alcohol, or a heart attack.
Carnitine uptake testThis is a special test done on a skin sample. It is used to diagnose carnitine deficiency disorders. It is sometimes used to test for carnitine transporter deficiency (CTD).
Carpal Tunnel SyndromePain, numbness and tingling in the hand and the arm, which is caused by a compressed nerve in the wrist.
CarrierA person who has one copy of a gene mutation for a particular autosomal recessive disorder (remember genes come in pairs). Carriers are not affected by the disorder. However, they can pass on the gene variant to their children. Children who inherit two such gene variants will be affected by the disorder. The term variants is now used in place of the term mutation.
CataractsThis is when the lens of the eye becomes cloudy and hard to see through. In a normal eye, the lens is almost transparent. Its job is to focus the things we are looking at onto the retina at the back of the eye so we can see objects at different distances clearly. Cloudiness of the lens causes dimming of the eyesight and fuzzy images. Cataracts are usually caused by exposure to too much sunlight or by aging. In young infants with galactosemia, cataracts may be caused by the buildup of galactose and other substances in the blood.
CellThe smallest living unit. Cells make up all organs and tissues in multi-cellular organisms, like humans. They can also live independently, as in bacteria and other microorganisms. At a minimum, a cell is surrounded by a membrane, contains DNA at some stage in its life, and is able to replicate itself into two equal parts.
Cerebral infarctA cerebral infarction is a brain injury in which a cluster of brain cells die when they don't get enough blood. If it causes symptoms in the body it is called a stroke. If it is only seen on MRI it is called a silent cerebral infarct.
Cerebral palsy (CP)This is a life-long condition that causes uncoordinated movements and spasticity (tight muscles of the limbs). It is caused by lack of oxygen to the brain. This damages the part of the brain that controls movement.
Chaperone therapy(Also known as Pharmacological chaperone therapy) is a new type of medicine using chaperones. Chaperones are small molecules that help enzymes become functional by helping them take the correct shape and by helping them stay stable. Increasing the function and stability of specific enzymes may help prevent or slow down some disease symptoms.
Cheek swabThis is a cotton covered stick that is used to painlessly collect cells from the inside of the mouth. The cotton tip is swirled on the inside of the cheek and then placed in a sterile tube. The cells collected are used for specific genetic tests.
ChemotherapyThis describes treating a disease by using chemicals or drugs.
ChlorideThis is a chemical (ion) that is found in water, salt and the fluids of the body. Chloride helps the body maintain a normal fluid balance. People with cystic fibrosis have excess chloride in their sweat.
ChoreaThis is a movement disorder in which people cannot control the movement of their limbs and head. The involuntary movements are often rapid and jerky..
ChoreoathetosisThis describes episodes of involuntary jerking movements combined with movements that are often irregular and twisting. These movements can flow from one body part to another. They commonly affect the arms, legs, trunk, and the muscles of the face.
Chorionic Villus Sampling (CVS)This is a special test done early in pregnancy. During CVS, a small sample of the placenta is removed for testing. This sample can be used to test for certain genetic disorders in the fetus. CVS is usually done between 10 and 12 weeks of pregnancy.
ChromosomeA strand of DNA contained within a cell. Each chromosome contains many thousands of genes. In humans, there are a total of 46 chromosomes, half of which come from each parent. The combined total of all chromosomes in a cell is the genome.
ChronicAny condition that lasts for a long period of time or occurs frequently. For example, diabetes and hemochromatosis are both chronic conditions.
CirrhosisThis is scarring of the liver. It can result from serious liver problems. It has many causes. Certain metabolic disorders, alcoholism, some medications and some viruses can lead to cirrhosis.
CitrullineThis is an amino acid made by the body. It does not usually need to be eaten in the diet. It helps the body get rid of the ammonia, a harmful substance. People with citrullinemia have trouble clearing this amino acid from the body.
Clinical trialClinical trials test the effectiveness of new drugs or treatments. These studies determine how well the treatments work, what risks are associated with them, and whether they work better than the current treatment.
ClitorisThis is a small organ located under a fold of skin at the front of the labia in females. It is made of a small amount of erectile tissue that allows sexual pleasure during stimulation.
Close relativeA parent, sibling, child, aunt, uncle, niece, nephew, grandparent, or grandchild are all considered close relatives.
ComaThis is a sleep-like condition from which a person cannot be awakened. People in a coma are unconscious. A coma can be caused by many things. Two causes are untreated low blood sugar (hypoglycemia) and a metabolic crisis.
Complete blood count (CBC)A blood test used to evaluate overall health and detect a wide range of disorders including anemia and infections. It can also give information about the amount of white blood cells.
Computed tomography (CT)This is a computerized x-ray machine used to take a series of pictures of areas inside the body. It allows doctors to get a detailed view of certain organs and bones of the body.
CongenitalThis means ‘present at or before birth.’ It usually refers to health conditions or birth defects that are present in a baby at or prior to birth.
ContracturesA tightening of muscle, tendons, or ligaments that prevents normal movement of the associated body part.
Corneal CloudingThe cornea is the eye, and can become ‘cloudy’ for a variety of reasons.
CortisolThis is the hormone made in the adrenal glands that helps keep the amount of glucose (sugar) in the blood at a normal level. It also helps protect the body from chronic stress by reducing inflammation and immune system reactions.
CortisoneThis is an artificial steroid medication similar to cortisol. It is used to treat children with congenital adrenal hyperplasia (CAH). It replaces the cortisol their own bodies are not making.
Cushing syndromeThis is a condition that occurs when your body is exposed to high levels of the hormone cortisol for a prolonged period of time. Signs of Cushing syndrome include: red or purple stretch marks on the skin, rounded face, fatty hump on the back, high blood pressure and bone loss. Most people with Cushing syndrome develop the symptoms from taking too much cortisone medication. The symptoms go away once the medication dosage is corrected.
Cyanocobalamin (CN-cbl)This is a form of vitamin B12 that can be given orally or by injection. This treatment increases the amount of vitamin B12 in the body. This is an important treatment for children with some forms of methylmalonic acidemia.
Cystine (cys) (or L-cystine)This is one of 20 amino acids that make up protein. It is also called “cys.” It is made by the body and does not need to be eaten in the diet. It may be part of a special medical formula given to people with homocystinuria or certain other metabolic disorders. It can also be given as a supplement in pill form.

DehydrationDehydration occurs when a person loses more water than they take in. Symptoms of dehydration are vague and include thirst, lightheadedness and diarrhea. Extreme dehydration requires hospitalization. In people with sickle cell disease, dehydration can trigger a crisis. Dehydration can be prevented by drinking plenty of water, especially when the individual is ill, in hot temperatures or participating in physical activity.
Deoxyribonucleic acid (DNA)Deoxyribonucleic acid (DNA) is a molecule found in the chromosomes that carries genetic information. DNA is composed of four units (called bases) that are designated A, T, G, and C. The sequence of the bases spell out instructions for making all of the proteins needed by an organism. A gene is a section of DNA that holds the instructions for a specific protein. A change in one or more of the DNA bases making up a gene is called a mutation. Some mutations change the protein instructions and can lead to particular health problems or disorders. Each parent passes half of their chromosomes, and thus half of their DNA instructions, onto their children. It is these instructions that cause certain traits, such as eye or hair color, to be inherited.
DetectionThe process of testing for a disease in a person who does not show the disease (non-symptomatic or asyntomatic). The goal of screening is to find the disease in its most important stages.
DexamethasoneThis is a synthetic type of steroid hormone similar to cortisol but more potent. One of its uses is for prenatal treatment of congenital adrenal hyperplasia in female fetuses. It may be given to a mother during pregnancy if her fetus is female and affected with congenital adrenal hyperplasia (CAH). It may reduce some of the physical changes to the genitals that occur with CAH, but may have other risks; thus, it is important to discuss potential treatment with this drug with your physician.
DialysisThis is a way to clean the blood when the kidneys aren’t working properly. Dialysis is done with a machine that acts as an “artificial kidney.” It filters the blood and removes the wastes.
DieticianThis is a person with special training in food and nutrition. A registered dietician (RD) has met the necessary educational requirements and has passed a national examination. If your child has a metabolic disorder, it is important for you to work with a registered dietician. They help create healthy food plans for people with metabolic disorders or other special needs.
Diphenylhydantoina medication used to treat and prevent seizures
Distant RelativeA relative who is not closely related to you. Distant relatives do not include parents, siblings, children, aunts, uncles, nieces, nephews, grandparents, and grandchildren. Great-aunts, cousins, and second cousins are examples of distant relatives.
Docosahexanoic acid (DHA)This is one type of “omega-3” fatty acid. DHA can be bought in capsule form as a supplement. These supplements may help prevent or lessen the loss of vision caused by LCHADD. DHA is found in small amounts in foods such as fish (tuna, sardines, salmon), red meat, eggs and some vegetable oils.
DystoniaThis is a condition that causes muscle spasms. These spasms can force the body into awkward and sometimes painful positions. It commonly affects the arms and the legs but can occur in any part of the body. People with dystonia also have episodes of involuntary jerking movements.

EchocardiogramEchocardiogram is a device that uses sound waves to produce images of a person’s heart.
EczemaThis is a skin condition that causes an itchy red rash. It also leads to rough, scaly skin or blisters. It is usually located on the face, elbows, knees and arms. Two of the many causes are allergies or certain inherited metabolic disorders.
ElectrocardiogramAn electrocardiogram is a simple, painless test that measures your heart's electrical activity. It's also known as an ECG or EKG. Every heartbeat is triggered by an electrical signal that starts at the top of your heart and travels to the bottom. Heart problems often affect the electrical activity of your heart
EndocrinologistThis is a doctor with special training in endocrine conditions –disorders caused by problems with one or more endocrine glands and their hormones. Some of the endocrine glands in the body include the adrenal glands above the kidneys, the pituitary glands, the pancreatic islets, and the thyroid glands. Some endocrine conditions include diabetes, hypothyroidism and congenital adrenal hyperplasia.
EnzymeA molecule that helps chemical reactions take place. For example, enzymes in the stomach speed up the process of breaking down food. Each enzyme can participate in many chemical reactions without changing or being used up.
Enzyme Replacement TherapyA type of therapy that can be used in some metabolic disorders. In people who have certain enzymes either missing or not working correctly, an IV infusion that contains the enzyme can be given. Enzyme replacement therapy is not a cure, but can help with the health problems and symptoms of the disorder.

Fallo ovariano prematuroEsta es una condición en la cual los ovarios dejan de funcionar muy temprano (antes de los 40). Esto causa que el ciclo menstrual pare. Ocurre aproximadamente en 1% de todas las mujeres. Algunas veces es causado por la diabetes, otras enfermedades hormonales, enfermedades autoinmunes, y puede ser el resultado de tratamientos de cáncer u otros medicamentos. Ocurre a menudo en mujeres con galactosemia. Los síntomas incluyen calenturas, cambios de humor, sudores nocturnos, sequedad vaginal é infertilidad.
False negativeA test result indicating that a person does not have a mutation or change predisposing them to a disease when, in fact, they do have this mutation or disease.
False positiveA test result indicating that a person has a mutation or a disease when, in fact, they do not have a mutation or disease.
Family medical historyInformation about the medical conditions that affect your family members. Doctors can use your family medical history to determine what disease you may be at higher risk for developing.
FatFat is one of the three main nutrients in food (carbohydrates, fat, protein). Some foods that contain fat are butter, margarine, oils, nuts, meats, poultry, fish and some dairy products. Extra calories from food are stored as body fat. Stored body fat provides the body with a reserve supply of energy.
FatigueFatigue is a feeling of weariness, tiredness, or lack of energy. Fatigue can be a normal and important response to physical exertion, emotional stress, or lack of sleep. However, it can also be a sign of a more serious health disorder.
Fatty acid oxidationThis is the process used by the body to change fatty acids, the building blocks of fat, into energy. It happens in the mitochondria – the small energy-producing parts found in each cell of the body.
Fatty acid oxidation disorders (FAODs)This is a group of rare inherited conditions. FAODs are caused by missing or non-working enzymes. Normally, many enzymes are used by the body to break down fat into energy. In people with FAODs, one of these enzymes is not working and fat cannot be used for energy. If these conditions are not treated, they can lead to serious health problems.
Fatty acid oxidation probeThis is a special test done on a skin sample. It can be used to diagnose certain fatty acid oxidation disorders (FAODs). It is sometimes used to test for long-chain fatty acid disorders such as LCHADD and VLCADD. It can also be used to test for these disorders during pregnancy.
Fatty acidsThese are the building blocks of fat. Fat from food is broken down by enzymes into fatty acids. These are changed by other enzymes and are used as energy or stored as body fat. Some types of fatty acids are: short-chain, medium-chain, long-chain, and very-long chain.
FerritinFerritin is a protein that is normally found inside the cells of the body. The ferritin test measures how much iron is stored within the cells. The ferritin test shows whether a person has too much or too little iron in his or her cells.
Fetal blood samplingThis is a special test done during pregnancy. A needle is used to remove a small amount of blood from the umbilical cord of the fetus. This blood sample can be used to test for certain genetic disorders in the fetus. Fetal blood sampling, also called PUBS, is usually done between 18 and 23 weeks of pregnancy.
Fetal echocardiogramA fetal echocardiogram is an echocardiogram done during pregnancy. It is usually done between 20-22 weeks of pregnancy.
Fetal ultrasoundFetal ultrasound (also known as a fetal sonogram) is an imaging technique that uses high-frequency sound waves to produce images of a baby while still in the mother’s womb (uterus).
First-degree relativeA relative who is a person’s biological mother, father, full sibling, or child. Step parents, step children, or half siblings are not first degree relatives.
Florinef (Fludrocortisone)This is a salt-maintaining medication used by people with salt-wasting CAH. It is taken in pill form and can help prevent adrenal crises in babies and children with salt-wasting CAH.
Flow cytometry (FCM)A laboratory technique used to count cells, sort cells, and learn about cells one at a time. This test can give information about the amounts of the different types of white bloods cells, such as T cells and B cells.
Folic AcidFolic acid is a form of vitamin B9. Folic acid is required to make healthy red blood cells and to prevent anemia. Folic acid can be found in certain foods and it can also be bought in pill form. It is recommended that people with Hemoglobin H take folic acid.
FontanelThese are the areas on the top middle of a baby’s skull that are covered by membranes and skin but not yet by bone. They are also called the ‘soft spots.’ The anterior fontanel is located in the front of the skull just above the forehead. It is the largest soft spot and should be closed by about 18 months. Babies with untreated congenital hypothyroidism may have very large fontanels that are delayed in closing.

Gabapentina medication used to treat nerve pain and seizures
GalactoseThis is one of the types of sugar molecules that make up lactose, the main type of sugar in milk and all products that contain milk. Galactose is found in milk and all milk products such as cottage cheese, yogurt, ice cream, buttermilk, and cheese. Galactose is also in sugar beets and a few other fruits and vegetables. It is also found in fillers used in some packaged foods and some medications.The milk sugar lactose is broken down in the digestive tract into two smaller sugars, galactose and glucose. Galactose is then changed into glucose so it can be used as fuel for the body. Galactose is also made by the body.
Galactose-1-phosphate uridyl transferase (GALT)This is an enzyme that is produced by the body and breaks down galactose. Galactose is a form of sugar that is found in milk and milk products. GALT breaks down galactose into glucose which is used to provide the body with energy.
GallstonesGallstones are hardened balls of digestive fluid that form in the gallbladder. The gallbladder is the organ that releases digestive fluid during digestion. Gallstones can be as small as a grain of sand or as large as a golf ball. They cause no symptoms in some people and many complications in others. Signs of gallstones include yellowing of the eyes and pain in the upper right abdomen.
GastroenterologistA doctor who specializes in conditions affecting the digestive system (the organs in the body that eat and digest food)
GeneA segment of DNA that contains the instructions to make a specific protein (or part of a protein). Genes are contained on chromosomes. Chromosomes, and the genes on those chromosomes, are passed on from parent to child. Errors in the DNA that make up a gene are called variants and can lead to diseases.
Gene therapyGene therapy – a type of treatment that transplants normal working genes into cells to replace non-working genes in order to treat genetic disorders. There are many ways that gene therapy can be done. Sometimes, a gene with a disease-causing variant can be replaced with a healthy gene. Sometimes, a gene with a disease-causing mutation can be inactivated or “silenced.” And sometimes, a new gene can be put into the body to help fight a disease. Some gene therapies are still experimental.
GeneticRelating to (or due to) genes and heredity or the field of studying genes and heredity.
Genetic codeThe genetic code determines how the sequence of bases in a gene code for the sequence of amino acids in a protein. A gene is made of bases that are designated A, T, G, and C. Each series of three bases is essentially a word that codes for one of the 20 amino acids that make up all proteins. For example, the sequence AAG within a gene tells a cell to insert the amino acid lysine into a growing protein.
Genetic counselingGenetic counseling gives patients and their families’ education and information about genetic-related conditions. It can help families make informed decisions. It is often provided by Genetic counselors or Medical geneticists who have special training in inherited disorders.
Genetic counselorThese are health care providers who have special training in genetic conditions. They help families understand genetic disorders and how they are passed down. Genetic counselors offer information and support to people who have genetic conditions in their families or are concerned that they may have a child with an inherited disorder.
Genetic mapA map of where genes are located relative to each other on the chromosome. Genetic maps are also called linkage maps.
Genetic markerAn identifiable region of DNA that is at a known location on a chromosome. Genetic markers are used to help scientists locate where a gene is on a chromosome. Scientists who are looking for genes that cause a specific disease or trait can look at the DNA of family members with the disease and compare it with the DNA of family members without the disease. If they find that certain genetic markers are present in the group with the disease, then the scientists can narrow their search to the area surrounding that marker.
Genetic metabolic specialistThis is a doctor or medical geneticist who has special training in diagnosing and treating metabolic disorders. They often work in university hospitals or large medical centers.
GeneticistA person who specializes in genetics.
GenitalsThis is a term use to describe the external sexual organs in both males and females. Male genitals include the penis and scrotum; female genitals include the vagina, clitoris and labia.
GenomeAll of the genetic material (DNA) contained in a full set of chromosomes in an organism. In humans, about three billion base pairs make up our genome.
Genomic DNAThe DNA that is found in the nucleus of a cell. Most of our genes are contained in the genomic DNA. However, some genes are contained within tiny organs called mitochondria that are within cells. This is called mitochondrial DNA.
GlaucomaThis is a serious eye condition. It causes increased pressure of the eyeball. If it is not treated, it can damage the nerve to the eye and cause blindness. If detected and treated in time, blindness can be prevented. Glaucoma is the second leading cause of blindness in the United States.
GlucoseThis is a type of sugar made from the carbohydrates in food. Glucose is found in the blood. It is the main source of energy for the body and brain.
Glutaric acidThis is a harmful waste product made when certain amino acids (lysine, tryptophan and hydroxylysine) are broken down in the body.
Glycine (gly)This is one of 20 amino acids that make up protein. It has many functions, one of which is helping cells create energy for the body. It is made by the body and does not need to be eaten in the diet. It is also available as a supplement. People with isovaleric acidemia (IVA) are often given glycine to help prevent health problems.
GlycogenGlycogen is the storage form of glucose. When the body does not need to use all of its available glucose, it stores it mainly in the liver and muscles as glycogen. Glycogen is made up of many connected molecules of glucose.
Glycogen Storage DisorderThese are a group of rare inherited disorders. People with glycogen storage disorders have problems either with the buildup or breakdown of a sugar called glycogen. When the enzymes involved in these processes are missing or not working properly, glycogen can build up in the body and cause a variety of health problems.
GoiterThis is an enlarged thyroid gland. It shows up as a swelling in the front of the neck. It can occur with different types of thyroid disease. Both hypothyroidism (low thyroid hormone) and hyperthyroidism (excess thyroid hormone) can cause goiters. They are also common in people with iodine deficiency. The enlarged thyroid will return to normal size once the underlying thyroid condition is treated.
Growth PlatesThe areas at the end of the long bones of the body that stay open during childhood to allow further growth. The cells of the growth plate divide when stimulated by growth hormone. After the growth plates close at the end of puberty, the bones cannot grow any longer. A person whose growth plates have closed has reached his or her final adult height.

HematologistA hematologist is a doctor who specializes in treating patients with blood disorders. Children with inherited blood conditions may have frequent check-ups with a hematologist.
Hematopoeitic Stem Cell TransplantIn this procedure, stem cells from bone marrow, blood, or umbilical cord blood are taken from another person (donor) and implanted into the patient. The patient and donor must be a genetic match. There are many risks associated with stem cell transplants.
HemoglobinHemoglobin is the protein in red blood cells that carries oxygen from the lungs throughout the body. In each red blood cell, there are hundreds of hemoglobin molecules. Hemoglobin molecules are made of two subunits, alpha and beta. Both the alpha and beta subunits are needed for hemoglobin to function correctly. When there is a change in the way hemoglobin is made, the red blood cells cannot deliver oxygen as efficiently.
HereditarySomething that is passed on from a parent to the child, usually through the genes.
Homocystine (hcy)This is a type of amino acid made by the body. High levels can occur in people with homocystinuria or certain other metabolic disorders.
HormonaLas hormonas incluyen muchos diferentes tipos de químicos que actúan como mensajeros alrededor del cuerpo. Las hormonas son fabricadas por glándulas endocrinas específicas que se secretan en la sangre cuando las necesitan otras partes del cuerpo. Las hormonas viajan a otros órganos y tejidos en el cuerpo para avisarles a que hagan algo. Por ejemplo, la insulina es una hormona que le da una señal a las células de músculo y de grasa para que remuevan glucosa de la sangre y que entre en a las células.
Hormona estimulante de la tiroidesEsta es una hormona hecha por la glándula pituitaria localizada en la base del cerebro. La misma es secretada cuando hay muy poca hormona tiroidea (tiroxina) en la sangre. Su trabajo es el de estimular a la glándula tiroides para que secrete más hormona tiroidea. Las personas con hipotiroidismo no producen suficiente hormona tiroidea por lo cual la glándula pituitaria secreta más TSH para poder elevar la cantidad de la hormona tiroidea en la sangre. Las pruebas de ambos el nivel de tiroxina (T4) el cual es bajo en personas con hipotiroidismo, y el nivel de TSH, el cual es elevado en personas con la misma condición, ayuda a los médicos a hacer la diagnosis.
HormoneHormones include many different types of chemicals that act as messengers around the body. Hormones are made by specific endocrine glands and are secreted into the blood when needed by other parts of the body. Hormones travel to other organs and tissues in the body to signal them to do something. For example, insulin is a hormone that signals muscle and fat cells to remove glucose from the blood and enter the cells.
HydrocephalusThis is also sometimes called 'water on the brain.' It occurs when extra fluid builds up in the ventricles - the inner chambers of the brain. It is often caused by a block in one of the chambers of the brain that does not allow the fluid to drain. When fluid builds up, it causes the ventricles and the skull to expand. It can be present at birth or can happen later in life. If it is not treated, it can cause learning disabilities or intellectual disabilities.
HydrocortisoneThis is the synthetic version of cortisol. It can be taken in pill form or by injection. It is a medication needed by people with CAH throughout life. It is also called ‘cortisone.’
Hydrops fetalisHydrops fetalis is the accumulation of fluid in two or more body parts of a developing fetus. Hydrops fetalis can be detected on ultrasound. Developing fetuses with hydrops fetalis are at risk for serious complications.
HydroxocobalaminThis is a form of vitamin B12 that is given by injection. These injections increase the amount of vitamin B12 in the body. This is an important treatment for children with some forms of methylmalonic acidemia.
HydroxylysineThis is an amino acid made by the body. When it is broken down, it makes glutaric acid.
HyperactivityThis refers to children who are unusually overactive. These children have serious problems sitting still. They tend to fidget and run around much more than usual. Some children with hyperactivity need treatment. They may be helped by behavior treatment, medication or both of these therapies.
HyperplasiaThis is an abnormal increase in the number of cells in a particular organ or tissue. It causes the organ or tissue to become larger than normal.
HypertoniaThis is an increase in muscle tone that leads to tight muscles. It also causes stiff, tight joints. It can be caused by injury, certain diseases or genetic disorders.
HypoglycemiaThis happens when there is too little sugar (glucose) in the blood. It may cause a person to feel nervous, shaky, weak, or sweaty. It may also cause headache, blurred vision, and hunger. If left untreated, it can cause unconsciousness (coma) and sometimes even death.
Hypoplastic left heart syndromeThis is a condition when parts of the left side of the heart do not develop completely. Normally, the left side of the heart pumps oxygen-rich blood to the rest of the body. If the left side of the heart is not developed completely, there is not enough oxygen-rich blood in the body.
HypothyroidismThis is a condition in which the person does not make enough thyroid hormone. It is most common in adult women and causes symptoms such as cold, pale, dry skin, brittle hair and nails, fatigue, weight gain and sluggishness. When the thyroid is not making enough hormone at birth, it is called congenital hypothyroidism. Hypothyroidism is treated by a medication that replaces the natural thyroid hormone the person cannot make on his or her own.
HypotoniaThis is a decrease in muscle tone that leads to loose or weak muscles and joints. Babies with hypotonia may have limbs and joints that feel “floppy” like a rag-doll. It can be caused by brain damage, muscle disorders or genetic conditions.

Immune globulinA treatment for SCID that gives the body antibodies that would normally be made by the B cells to help fight off infections. It can also be called immunoglobulin or gammaglobulin.
Immune systemThis system protects the body from diseases and germs. Through a series of steps called the immune response, the immune system attacks things that infect the body and cause disease.
ImmunologistA doctor who has special training about the immune system and how to treat disorders of the immune system
In vitro fertilization (IVF)In vitro fertilization (IVF) is the process of fertilization by combining an egg and sperm in a laboratory dish. When the IVF procedure is successful, an embryo develops which must then be put into the mother’s womb (uterus).
Infectious disease specialistA doctor who has special training in the diagnosis and treatment of infectious diseases.
InfluenzaThis is also called ‘the flu.’ Influenza is a viral infection of the respiratory tract (nose, throat and lungs). Typical symptoms of influenza include: high fever, body ache, chills, sore throat, weakness, muscle aches, cough, and headache.
Informed consentVoluntarily agreeing to do something after receiving and understanding all of the relevant information. Participation in all medical trials requires informed consent.
Inguinal herniaWhen tissue, such as part of the intestine, protrudes through a weak spot of the inguinal canal (groin area).
InheritAcquiring a trait from one’s parents. Most traits, such as eye color or hair color, are inherited from a parent through genes.
InsulinThis is a hormone made in the pancreas. It controls the level of glucose (sugar) in the blood.
IodineThis is an element needed in order for the body to make thyroid hormone. It is found in certain foods such as shellfish, seafood and seaweed. Without enough iodine in the diet, a person will develop hypothyroidism and possibly a goiter. In the United States, iodine deficiency is rare because iodine is added to table salt (iodized salt).
IronIron is a natural element that is needed for the body to function properly. Iron can be found in many foods. Having a high amount of iron can cause damage to organs. Talk with your doctor about the risks and benefits if your child takes iron supplements or has blood transfusions.
Isoleucine (ile)This is one of 20 amino acids that make up protein. It is not made by the body and must be eaten in the diet. It is found in all foods that contain protein.
IV (Intravenous)This is a small tube placed into a vein, usually in the hand or arm. Medications and nutrients can be given through this tube directly into the blood. IV’s are often used in the hospital to give fluids, glucose and medication over a long period of time.

JaundiceThis is a yellow color to the skin and whites of the eyes. It is often a sign of liver damage.

KaryotypeAn arranged picture of the chromosomes from a single cell. The chromosomes are arranged in order (by numbered pair, size and shape) from a picture of chromosomes taken under a microscope. A karyotype allows cytogeneticists (scientists who study chromosomes) to see whether an individual has any extra or missing genetic material, or any rearrangements that are large enough to be seen.
KetonesThese are substances made when the body breaks down fat (fatty acids) for energy. In people with certain metabolic disorders or diabetes, ketones can build up in the blood and spill over into the urine. If ketones build up in the blood, they can cause acidosis which can lead to serious health problems.

L-CarnitineThis is a natural substance found in muscle cells. It helps the body make energy from the fat in food and the fat stored in the body. It also helps the cells get rid of harmful wastes made during the breakdown of fat. Carnitine supplements may be used as a treatment for some metabolic disorders.
L-thyroxine (levothyroxine)This is the most common synthetic form of thyroxine (thyroid hormone). It is given in pill form to children or adults who have hypothyroidism. It is important that the pills be taken on a daily basis. Stopping this medication causes the symptoms of hypothyroidism to return.
LabiaThese are the two pair of skin folds that surround the vagina in females. The outer pair of folds is called the labia majora. The inner pair of folds is called the labia minora.
Lens dislocationThis is a condition in which the lens of the eye becomes loose and moves out of place. If it is not treated, it can lead to a serious eye condition called glaucoma. This can lead to blindness if left untreated.
LethargyAbnormal drowsiness.
Leucine (leu)This is one of 20 amino acids that make up protein. It is not made by the body and must be eaten in the diet. It is found in all foods that contain protein.
Long-chain fatty acids (LCFA)This is one of many types of fatty acids, the building blocks of fat. Long-chain fatty acids are made up of chains of 12 or more carbon atoms.
LymphocytesA group of cells that are a part of the immune system. These cells allow the body to remember and recognize previous invaders and help the body destroy them.
Lysine (lys)This is one of 20 amino acids that make up protein. It is not made by the body and must be eaten in the diet. It is found in all foods that contain protein.
Lysosomal Storage DisorderThese are a group of rare inherited disorders. People with lysosomal storage disorders have problems with breaking down large molecules within the lysosome. When the enzymes inside lysosomes are missing or not working properly, there can be a buildup of these molecules which causes a variety of health problems.
LysosomeLysosomes are like recycling centers for cells. They are small sacs filled with many enzymes that help break down large molecules into smaller molecules that the body can re-use.

Magnetic Resonance Imaging (MRI)This test uses magnetic waves to make pictures of the body. It can sometimes be used instead of x-rays to look at areas inside the body. It is often used to look at the brain or other inner organs.
MaternalHaving to do with the mother.
Maternal PKU syndromeThis is a group of birth defects found in some babies born to women who have PKU. Women with PKU who are not treated before and throughout pregnancy have a high chance to have babies with one or more of these health problems. Symptoms of maternal PKU can include microcephaly (heads and brains that are too small), intellectual disabilities, heart defects, and low birth weight.
MeaslesThis is a very contagious type of viral infection. It is also called ‘rubeola.’ Symptoms include red spots and a skin rash, fever, sneezing, nasal congestion, cough, and fatigue.
Meconium ileusMeconium is the stool-like substance found in the intestines of all newborn babies. When a baby or fetus is found to have overly thick meconium that blocks the small intestine, it is called ‘meconium ileus.’ This is found in about 15-20% of babies with Cystic Fibrosis. Some of the symptoms caused by meconium ileus include: vomiting, bloated abdomen and failure to have a bowel movement. It can be treated by enemas or medications. Rarely, surgery is needed to remove the blockage.
Medical geneticistA doctor who treats and diagnoses genetic conditions.
Medical release formA form that gives permission to get a person’s medical records. Medical release forms have to be signed by the person whose records you wish to access or by a close relative if that person is deceased.
Medium chain triglyceride oil (MCT oil)This is a special type of oil made up of medium chain triglycerides – a type of fatty acid. MCT oil can be used for energy by people with long chain fatty acid oxidation disorders (LCHADD and VLCADD). A doctor’s prescription is needed to get MCT oil. It should be used only under the guidance of a registered dietician.
Medium-chain fatty acids (MCFA)This is one of many types of fatty acids, the building blocks of fat. Medium-chain fatty acids are made up of chains of 4 to 12 carbon atoms.
Metabolic acidosisThis happens when acidic substances build up in the blood. It can cause rapid breathing, confusion, and extreme sleepiness. If not treated, it may lead to shock, coma or death.
Metabolic crisisThis is a serious health condition caused by low blood sugar and the build-up of toxic substances in the blood. Symptoms of a metabolic crisis are poor appetite, nausea, vomiting, diarrhea, extreme sleepiness, irritable mood and behavior changes. If not treated, breathing problems, seizures, coma, and sometimes even death can occur.Metabolic crises happen more often in people with certain metabolic disorders (some fatty acid oxidation disorders, amino acid disorders, and organic acid disorders). They are often triggered by things like illness or infection, going without food for a long time, and, in some cases, heavy exercise.
Metabolic disorderPeople with metabolic disorders are not able to break down certain substances in food. Too much or too little of a certain substance (like fat, carbohydrate or protein) can cause serious health problems. Fatty acid oxidation disorders (FAODs), amino acid disorders (AAs) and organic acid disorders (OAs) are three types of metabolic disorders.
Metabolic doctorThis is a doctor or medical geneticist who has special training in diagnosing and treating metabolic disorders. They often work in university hospitals or large medical centers.
Metabolic Genetic SpecialistThis is a doctor or medical geneticist who has special training in diagnosing and treating metabolic disorders. They often work in university hospitals or large medical centers.
MetabolismThis is the process of using food substances for energy and for growth and repair of the body.
Methionine (met)This is one of 20 amino acids that make up protein. It is not made by the body and must be eaten in the diet. It is found in all foods that contain protein.
Methylmalonic acidThis is a substance made when the body digests food containing protein and fat. Normally, it is quickly changed by the body into other substances. If the body is missing an enzyme needed to break down methylmalonic acid, it builds up in the blood and causes illness. Excess methylmalonic acid is found in the blood of people with methylmalonic acidemia.
MicrocephalyThis is a head size that is too small for a child’s age. It is usually caused by lack of brain growth. It can happen for many reasons. Many children with microcephaly have intellectual disabilities.
MitochondriaThese are the parts within each cell that make energy for the body.
Motor controlThe process of starting and using muscles for purposeful movement
Motor neuronsA particular type of nerve cell that carries information from the brain to the muscles.
Muscle toneIn order to hold our posture and control our movements, a certain amount of tension is needed in our muscles. This tension is called “muscle tone.” People with hypotonia have too little tension in their muscles and appear “floppy.” People with hypertonia have too much tension in their muscles and have problems with tight, rigid muscles and joints.
Muscle tone
MutationA change or alteration that occurs in the DNA. Mutations can be caused by the environment (sun, radiation, or chemicals), aging, or chance. Often the causes of mutations are never known. Some mutations do not affect the information contained in the DNA. Other mutations have serious consequences on how that gene functions.
MyxedemaThis is a condition seen in people with hypothyroidism. It causes swelling of the skin and an enlarged tongue. People with myxedema develop thick and puffy eyes, cheeks, lips and nose. Dry skin also occurs. Myxedema symptoms go away once the hypothyroidism is treated.

Nasal polypsThese are small sac-like growths in the inner lining of the nose.
Neurologic crisesThese are episodes of weakness, pain, or numbness caused by nerves that are not working correctly. They often affect the arms and legs but can happen in any part of the body. Breathing problems and rapid heartbeat sometimes also occur. These episodes are more common in people who have tyrosinemia or certain other metabolic disorders. Medication can often stop or prevent these crises.
NeurologistA specialist in the anatomy, functions, and organic disorders of nerves and the nervous system.
Newborn Metabolic ScreeningA screening test that looks for different metabolic disorders using a small sample of blood taken from a newborn’s heel. A positive or abnormal newborn metabolic screening result means that slight differences were found in the baby’s blood, and further testing is needed to figure out if the baby has a metabolic disorder.
Newborn ScreeningA screening test that looks for different disorders using a small sample of blood taken from a newborn’s heel. A positive or abnormal newborn screening result means that there are slight differences that were found in the baby’s blood, and further testing is needed to figure out if the baby has a metabolic disorder.
NitisinoneThis is the medication used to treat tyrosinemia. The brand name of this drug is Orfadin. It was previously called NTBC. This medication helps improve liver and kidney function in people with tyrosinemia.
NitrogenThis is an element that makes up part of protein. It is released when protein is broken down in the body. The body changes it into ammonia (one nitrogen molecule combined with three hydrogens). Since ammonia is harmful to the body it is usually changed to urea. Urea is a non-toxic substance that is removed from the body in the urine.
Nodular cirrhosisThis is a rare type of scarring of the liver. It can occur in people with tyrosinemia. It often gets worse over time and can lead to serious liver problems. If not treated, it can cause liver failure, liver cancer, and death.
NonsymptomaticNot showing any of the signs of the condition or disease.

Organic acid disorders (OA)This is a group of rare inherited conditions. OA disorders are caused by one or more enzymes that do not work properly. People with these conditions cannot digest certain parts of protein from the food they eat. This causes harmful substances to build up in their blood and urine. This can cause serious effects on health, growth, and learning.
Organic acidsThese are substances in the cells of the body that help break down fat, sugar and protein from the food we eat. Babies with organic acid disorders often have excess amounts of specific organic acids in their blood and urine. This can cause serious effects on health, growth, and learning.
OsteoporosisThis is a condition that causes the bones to become thinner over time. People with this condition have a higher chance for bone fractures.
Overriding aortaThe aorta is the main blood vessel that carries oxygen-rich blood from the heart to the rest of the body. It is usually attached to the left ventricle. In cases of tetralogy of Fallot, the aorta is positioned between the right and left ventricles, directly on the defect of the ventricular septum. As a result, oxygen-poor blood from the right ventricle flows into the aorta and the rest of the body.
Oxygen saturationOxygen saturation is a measure of how much oxygen the blood is carrying as a percentage of the most oxygen the blood can carry.

PancreasThis is a large organ behind the stomach. One of its jobs is to make digestive enzymes and release them into the small intestine. The digestive enzymes are essential for food (carbohydrates, proteins and fats) to be broken down into small enough nutrients to get into the blood. Without them, people cannot absorb enough nutrients and will develop malnutrition and poor growth. The pancreas also makes the hormone insulin which is needed for glucose (sugar) to leave the blood and get into body cells.
Pancreatic insufficiencyThis is the lack of pancreatic (digestive) enzymes due to a blocked or a malfunctioning pancreas. Lack of digestive enzymes leads to incomplete digestion of food and causes malnutrition.
PancreatitisThis happens when the pancreas, an organ near the stomach, becomes inflamed. It causes severe abdominal pain. It can be caused by some metabolic disorders, gallstones or too much alcohol.
Pediatric cardiologistsPediatric cardiologists are specialized doctors who diagnose and treat diseases affecting the heart and blood vessels in children and infants.
PedigreeA medical drawing that includes all of a person’s close relatives, the relationship between family members, and health information. A pedigree is used by health care professionals to analyze a family for genetic diseases.
PenicillinPenicillin is a prescription medication that works to prevent infections. Children with sickle cell disease take penicillin daily. Talk with your doctor about the risks and benefits of taking penicillin.
Peroxisomal DisordersPeople with peroxisomal disorders have missing or non-working enzymes/proteins in their peroxisome. As a result, they have problems breaking down certain large molecules into usable forms. This leads to a build-up of these molecules, which causes a variety of health problems.
PeroxisomePeroxisomes are like recycling centers for cells. They are small sacs filled with enzymes and proteins that do different jobs. Some enzymes help to break down larger molecules into smaller molecules that the body can use. Other proteins help to transport molecules into the peroxisomes.
Phenylalanine (Phe)This is one of 20 amino acids that make up protein. It is also called “Phe.” It is not made by the body and must be eaten in the diet. It is found in all foods that contain protein.
Phenylketonuria (PKU)This is a group of birth defects found in some babies born to mothers who have PKU. Women with PKU who are not treated before or during pregnancy have a high risk of having babies with one or more of these health problems. Maternal PKU symptoms may include microcephaly (heads and brains that are very small), intellectual disability, heart defects, and low birth weight.
PlateletsThis is a type of blood cell that helps to clot the blood. Platelets help prevent or control bleeding.
PneumoniaAn infection of the air-sacs (alveoli) of the lungs that causes inflammation (swelling and redness) and fluid build-up. Symptoms include fever, chills, muscle aches and weakness, severe chest pain, cough, shortness of breath and difficulty breathing. It can be dangerous, especially in young children and the elderly.
Polycystic ovary syndrome (PCOS)This is a condition that occurs in women who make too much of the androgen (male-like) hormones. It occurs in about 5 to 10% of all women. Some of the features of PCOS include: multiple cysts on the ovaries, excess body hair, severe acne, abdominal obesity, abnormal or lack of periods, and infertility. Women with PCOS are also at increased risk for type 2 diabetes.
PolymorphismA change in the DNA sequence (variant) that is present in at least 1 percent of the population and is not considered harmful. One example of a polymorphism is in the hair color gene. Slight changes in the DNA sequences make the hair blond or brown.
Preimplantation genetic diagnosisPreimplantation genetic diagnosis (PGD) is also called Preimplantation Genetic Testing (PGT). It is a procedure used before implantation to find genetic changes within embryos genes or chromosomes. The embryos are created by using the technique called in vitro fertilization. The goal of PGD is to prevent certain diseases or genetic changes from being passed on to the child. The genetic change must be known before this procedure can be done.
Premature ovarian failure (POF)This is a condition in which the ovaries stop working too early (earlier than age 40). This causes the menstrual periods to stop. It is found only in about 1% of all women. It is sometimes caused by diabetes, other hormone disorders, autoimmune disorders, and can be a result of cancer treatments or other medications. It often occurs in women with galactosemia. Symptoms include hot flashes, mood swings, night sweats, vaginal dryness and infertility.
Primary immune deficiency disorders (PID)A group of conditions caused by genetic errors in the immune system.
Propionic acidThis is one type of fatty acid. Large amounts build up in the blood of people with a metabolic disorder called propionic acidemia. If not treated, this condition can cause serious health problems.
ProteinA molecule that makes up many parts of every cell in the body. Examples of proteins include hormones, enzymes, hair, and antibodies. Proteins are made up of 20 different types of individual units called amino acids. It is the order of these amino acids in a protein that determines what form and function a protein has. Each gene holds the instructions for making a single protein.
PseudodeficiencyA pseudodeficiency mutation causes less of an enzyme to be produced, but does not actually cause symptoms of the corresponding disease itself. Pseudodeficiency mutations can cause false positive screening results.
Psychiatric disorderThis is another term for mental illness. It can cause severe problems in a person’s thinking and emotions.
PsychosisThis is a mental disorder in which the person is not in contact with reality. It can include sensing things that aren’t really there (hallucinations) or having beliefs that aren’t based on reality (delusions).
Pulmonary atresia (with intact septum)Pulmonary atresia (with intact septum) is a heart defect present at birth with two main differences from a normal heart:
• The valve which allows blood to flow from the heart to the lungs – the pulmonary valve – is completely blocked, and
• The main pumping chamber on the right side – the right ventricle – has not developed normally.
Pulmonary stenosisThis condition occurs when the pulmonary valve (the valve that allows blood to flow from the heart to the lungs) cannot be fully opened. This means that the heart has to work harder to pump blood through the valve. As a result, not enough blood reaches the lungs.
PulmonologistA doctor who specializes in lung conditions and breathing problems
PulseA pulse is the throbbing of blood vessels created by the beating of the heart. It can most easily be felt in the wrist and neck.
Pulse oximetryPulse oximetry measures a baby’s pulse and how much oxygen a baby has in his or her blood (called oxygen saturation). Babies who have low oxygen levels in their blood may have a critical congenital heart defect.

Red blood cellsRed blood cells are the major component in blood that delivers oxygen from the lungs to the body tissues.
ReflexesAn automatic and involuntary action of an organ or muscle in response to a stimulus. Examples of reflexes include the kick of the lower leg when the anterior knee is tapped and pupil constriction in response to bright light. Sometimes, certain expected reflexes do not happen automatically. This is called an absence of reflexes.
Respiratory infectionsRespiratory infections are any infection that occurs to the respiratory system. The respiratory system is the breathing system.
RiboflavinThis is a one type of B vitamin (vitamin B2). It helps change carbohydrates, protein, and fat into energy for the body. Some foods high in riboflavin are dairy products, yogurt, cheese, meats, poultry, whole and enriched grains, and green vegetables. Some children with metabolic disorders may be helped by taking riboflavin supplements.
RicketsThis is a condition that causes soft and weak bones. It is often caused by a lack of vitamin D. People with liver or kidney disease have a higher chance of developing rickets.
Right ventricular hypertrophyIt is a condition that occurs when the muscles of the right ventricle (the lower right chamber of the heart) are thicker than normal. This happens because the right ventricle has to work harder to pump blood through the abnormal pulmonary valve (due to pulmonary stenosis).
RSV vaccine (respiratory syncytial virus)RSV the most common respiratory illness in babies and young children. It causes infection of the lungs and breathing passages. It is highly contagious. It can be very serious and sometimes life-threatening in a child with CF or other chronic lung disease.

ScoliosisAn abnormal sideways curvature of the spine
ScreeningThe process of testing for disease in a person who does not show signs of having the disease (nonsymptomatic or asymptomatic person). The goal of screening is to catch the disease in its early stages.
ScrotumThis is the loose pouch of thin wrinkled skin that holds the testicles in males. It is located just below the penis.
SeizuresThese are also called "convulsions" or "fits." During a seizure, a person loses consciousness and control of his or her muscles. It may also cause involuntary movements. Seizures can happen for many reasons. Some causes are metabolic disorders, a metabolic crisis, brain injury, and infection.
SequencingThe process of determining the order of the bases in a region of DNA.
ShockAlso called cardiovascular shock. This is a situation in which the brain is not receiving enough blood. Without proper bloodflow, the brain cells don't get enough oxygen and begin to shut down. The symptoms of shock include: confusion, irritability, rapid heart rate, and, if not treated, coma.
Short-chain fatty acids (SCFA)This is one of many types of fatty acids, the building blocks of fat. Short chain fatty acids are made up of chains of two to six carbon atoms.
SiblingA person who shares the same mother or father. A brother or sister who shares both parents is called a full sibling. A brother or sister who only shares one parent is called a half sibling.
Sickle cell crisisA sickle cell crisis is an episode of pain that occurs in people with sickle cell disease when they do not have enough oxygen in their tissues.
Sickle cell traitPeople with sickle cell trait have one working copy of the sickle cell gene and one non-working copy. Having sickle cell trait does not cause a person to be sick. A person with sickle cell trait can pass it on to his/her children and may be at risk to have a child with sickle cell disease. About 1/12 African Americans has sickle cell trait. Talk with your doctor about testing for sickle cell trait.
Sleep ApneaA sleep disorder where breathing repeatedly stops and starts throughout a period of sleep, either because the upper airway becomes blocked repeatedly during sleep, or the brain does not send signals needed for breathing.
SMN proteinSurvival motor neuron protein is a protein in the cells that helps build and maintain motor neurons. Motor neurons are special cells that help you move and control your muscles. When SMN protein is not working right, it causes muscle problems.
SpasticityThis is rigidity of the muscles and increased reflexes. It is caused by increased muscle tone. It results in abnormal tightness or stiffness of the muscles and joints.
SpleenThis is an organ located behind the stomach. It gets rid of old blood cells and helps fight infection. The spleen can enlarge in people with cirrhosis or with certain metabolic disorders.
SporadicOccurring occasionally or randomly. In medical terms, a sporadic disease is one in which the disease occurs in people with no family history and no inherited cause.
StrokeThis is when the blood or oxygen supply to part of the brain is stopped. It can be caused either by a blood clot or a leak in a blood vessel. A stroke may cause loss of speech and language and the ability to move certain body parts. If severe, it can cause death.
Substrate Reduction TherapyA type of treatment sometimes used for lysosomal storage disorders (LSDs), usually given as an oral medication. In some LSDs, there is a buildup of excess ‘substrate’ which is harmful; this therapy reduces the amount of harmful substrate in the body.
SuccinylacetoneThis is a harmful substance made from an amino acid called tyrosine. People with tyrosinemia can develop very high levels of this substance in their blood. If not treated, it can cause liver and kidney damage. It can also cause serious nerve problems.
SurveillanceThe process of monitoring or checking for signs or symptoms of a disease.
SusceptibilityThe likelihood that a person will develop a condition or disease.
SyndromeA group of symptoms and clinical findings that, when found together, make up a particular condition or disease.

T-cell receptor excision circles (TREC)TRECs are usually found in every newborn’s blood and are found when T cells are being produced.
T-cells (also called lymphocytes)A type of white blood cell that matures in the thymus gland. T cells are some of the cells that may be recruited during an immune response.
Tandem Mass SpectrometryA technology that may be used in newborn metabolic screening to test newborns for many different metabolic disorders. To do this, an instrument called a tandem mass spectrometer measures the level of certain compounds in the newborn’s blood. Too much or too little of these compounds could mean that the newborn has an inherited metabolic disorder.
Tetralogy of FallotTetralogy of Fallot is a condition caused by a combination of four heart defects that are present at birth:
• Ventricular septal defect or VSD- is a hole in the septum (or wall) between the heart’s two lower chambers – the ventricles.
• Pulmonary stenosis – is when the valve which allows blood to flow from the heart to the lungs –the pulmonary valve – cannot fully open.
• Right ventricular hypertrophy- is when the muscle of the main pumping chamber on the right side – the right ventricle – is thicker than usual.
• Overriding aorta- the main blood vessel that carries blood away from the heart – the aorta – is an overriding aorta when it is located in the wrong place, specifically when it is between the left and right ventricles, directly over the VSD.
ThalassemiasThalassemias are a group of inherited blood conditions caused by decreased production of hemoglobin.
ThiamineThis is one type of B vitamin. Thiamine is found in grains, pork, beans, seeds and nuts. It plays a key role in changing food into energy.
This is one of the 20 methionines (meth)Amino acids that make up the protein. They are not generated by the body and should be consumed in the diet. They are found in all foods that contain protein.
Threonine (thr)This is one of 20 amino acids that make up protein. It is not made by the body and must be eaten in the diet. It is found in all foods that contain protein.
Thymus glandAn organ that is important for the immune system. T cells mature in the thymus gland.
Thyroid stimulating hormone (TSH)This is a hormone made by the pituitary gland located at the base of the brain. It is released when there is too little thyroid hormone (thyroxine) in the blood. Its job is to stimulate the thyroid gland to release more thyroid hormone. People with hypothyroidism do not make enough thyroid hormone so the pituitary releases more TSH in order to try to increase the amount of thyroid hormone released. Testing for the level of both thyroxine (T4) which is low in people with hypothyroidism, and the level of TSH, which is high in people with hypothyroidism, helps doctors make the diagnosis.
Thyroid uptake and scanThis is an imaging test that looks at the structure and function of the thyroid gland. It can show whether the thyroid is in the normal place, has a normal size and whether it is working correctly. The scan is done by injecting a small amount of radioactive material into a vein or having the patient swallow it by mouth. The material collects in the thyroid gland so an imaging machine can create a picture of the thyroid.
ThyroxineThyroxine, also called T4, is the major thyroid hormone made by the thyroid gland. One of the essential components of thyroxine is iodine. This is why iodine deficiency results in hypothyroidism and goiter.
Total anomalous pulmonary venous returnTotal anomalous pulmonary venous return is a heart defect present at birth, where the veins leading from the lungs – the pulmonary veins – attach to the heart in abnormal positions.
TrackingThe process of testing a disease for a person who does not appear to have the disease (non-symptomatic or asymptomatic). The goal of tracking is to find the disease in its earliest stages.
Transposition of the great arteriesTransposition of the great arteries is a heart defect present at birth in which the two main blood vessels leaving the heart – the great arteries- are reversed.
TremorsShaking or trembling movements in one or more parts of the body caused by problems with the nerves
Tricuspid atresiaTricuspid atresia is a heart defect present at birth in which one of the valves (tricuspid valve) between two of the heart’s chambers is not formed. Instead, there is a solid wall of tissue between the chambers.
TruncatedTo be cut short or terminated early. In the case of a truncated protein, only the first part of the protein is made.
Truncus arteriosusTruncus arteriosus is a heart defect that is present at birth in which one large blood vessel leads out of the heart instead of two large vessels coming out of the heart.
Tryptophan (trp)This is one of 20 amino acids that make up protein. It is not made by the body and must be eaten in the diet. It is found in all foods that contain protein.
Tyrosine (tyr)This is one of 20 amino acids that make up protein. It is made by the body and does not need to be eaten in the diet.

UlcerAn ulcer is an open break in the skin that does not heal. Some children with sickle cell disease develop ulcers on the lower leg.
UltrasoundUltrasound is an imaging method that uses high-frequency sound waves to create an image of structures within a person’s body. Also see fetal ultrasound.
Umbilical herniaThis is an out-pouching of skin over the navel. Babies with untreated congenital hypothyroidism often have umbilical hernias. It can also be the result of a birth defect or may occur as a result of one of a number of other medical conditions.
UreaThis is a harmless waste product made by the body. Its job is to get rid of ammonia, a harmful substance made when protein is broken down for use by the body. The kidneys flush urea from the body in the urine.
Urea cycle disorder (UCD)These are inherited conditions that cause ammonia to build up in the body. Ammonia is a harmful waste product made during the breakdown of protein and its amino acid building blocks.

Valine (val)This is one of 20 amino acids that make up protein. It is not made by the body and must be eaten in the diet. It is found in all foods that contain protein.
VariantsA variant is a change or alteration in a person’s DNA sequence. Variants can happen in genes and affect how the gene functions. There are different types of variants – they can be non-problem causing (benign), disease-causing (pathogenic) or of unknown significance. The term variants is now used in place of the term mutation.
Vas deferensThese are the two thin tubes that carry sperm from the testes to the urethra during ejaculation. In some men, one or both can be missing from birth (congenital absence of the vas deference – CAVD) which is often seen in men with cystic fibrosis.
Ventricular septum defectNormally, the heart has four chambers. Two cameras are on the left and two on the right. The wall separating the left side of the right is called the septum. A defect of the ventricular septum is a hole in the wall between the two lower chambers of the heart (called ventricles). The hole allows oxygen-rich blood to be mixed from the left ventricle with oxygen-poor blood from the right ventricle.
Very long-chain fatty acidsThis is one of many types of fatty acids, the building blocks of fat. Very long-chain fatty acids are made up of chains of 21 to 32 carbon atoms.
VirilizationThis is a process in which male sex characteristics occur in a female or at an earlier age than normal in a boy. Some traits that occur with virilization include: increased body hair, facial hair, deepening of the voice, and male-pattern baldness (hair loss at the temples). Girls with virilization may have enlargement of the clitoris and fusion of the folds of the labia that make the labia resemble a scrotum.
Vitamin B12This is a type of B vitamin. It is also called cobalamin. It helps in the breakdown and use of food for energy. It also helps to make red blood cells and keep the nervous system healthy. It is found in meat, dairy products, and eggs. It can also be given by injection to people who have low levels or who have certain metabolic disorders.
Vitamin B6This is a type of B vitamin. It is also called pyridoxine. It helps in the breakdown and use of food for energy. It is found in beans, meat, fortified cereal, and some fruits and vegetables. It can also be bought in pill form. Vitamin B6 supplements are sometimes given to people with homocystinuria.
Vitamin DThis vitamin helps make strong bones and teeth. It also helps prevent a bone condition called “rickets.” Your skin makes vitamin D when you go out in the sun. It is also found in fortified milk and cereals, egg yolks, and fatty fish.

Wild typeThe version of the gene that is found most common in nature. The typical version of a gene.

X chromosomeOne of the two chromosomes that are responsible for determining the sex of an organism. The other sex chromosome is called the Y chromosome. Both the X and the Y chromosome contain several genes, only some of which are involved in determining sex. In humans, the X chromosome is the larger of the two sex chromosomes. Females usually have two X chromosomes and males usually have one X chromosome and one Y chromosome.
X-LinkedA mode of inheritance. X-linked genes are found on the X chromosome. They have a different inheritance pattern than other genes because women have two X chromosomes while men only have one. Any mutation on the X chromosome may not cause a disease in women if the gene on the other chromosome is normal. However, that same mutation on one X chromosome in men will cause the disease because they have no second copy of the gene to compensate.
X-linked recessiveThis is a pattern of inheritance in which a gene for a particular trait or disorder is located on the X chromosome. Genes that are ‘recessive’ cause traits or conditions only when they are paired with a dominant gene. Genes usually come in pairs, except on the sex chromosomes in males. Males have one X chromosome that they inherit from their mothers and one Y chromosome that they inherit from their fathers. If a gene on the X chromosome causes a particular trait or disorder, a male will always show that trait or condition as they do not have another gene to cover up its effects. Females usually have a normal copy of that gene on their other X chromosome which covers up the effects of the recessive gene. Some common X-linked recessive disorders include hemophilia, Duchenne muscular dystrophy and color blindness.

Y chromosomeOne of the two sex chromosomes that is responsible for determining the sex of an organism. The other sex chromosome is called the X chromosome. Both the X and the Y chromosome contain several genes, only some of which are involved in determining sex. In humans, the Y chromosome is the smaller of the two sex chromosomes. Most females have two X chromosomes and most males have one X chromosome and one Y chromosome.

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