FATTY ACID DISORDER
Disorder Name: Short chain 3-hydroxyacyl-CoA dehydrogenase deficiency
- What is SCHADD?
- What causes SCHADD?
- If SCHADD is not treated, what problems occur?
- What is the treatment for SCHADD?
- What happens when SCHADD is treated?
- What causes the SCHAD enzyme to be absent or not working correctly?
- How is SCHADD inherited?
- Is genetic testing available?
- What other testing is available?
- Can you test during a future pregnancy?
- Can other members of the family have SCHADD or be carriers?
- Can other family members be tested?
- How many people have SCHADD?
- Does SCHADD happen more often in a certain ethnic group?
- Does SCHADD go by any other names?
- Where can I find more information?
This fact sheet contains general information about SCHADD. Every child is different and some of this information may not apply to your child specifically. Very little is known about SCHADD and, at present, there is no standard treatment plan. Certain treatments may be recommended for some children but not others. Children with SCHADD should be followed by a This 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. in addition to their primary doctor.
WHAT IS SCHADD?
SCHADD stands for “medium/short chain 3-hydroxyacyl CoA dehydrogenase deficiency.” This disorder is also known as “3-hydroxyacyl CoA dehydrogenase deficiency.” It is one type of This 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. disorder. Some people with SCHADD have problems using Fat 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. for energy. However, most babies with A 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. results showing SCHADD never have any symptoms.
|Fatty Acid Oxidation Disorders:
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. are a group of rare Acquiring a trait from one’s parents. Most traits, such as eye color or hair color, are inherited from a parent through genes. conditions. They are caused by enzymes that do not work properly.
A number of A 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. are needed to break down fats in the body (a process called fatty acid oxidation). Problems with any of these enzymes can cause a fatty acid oxidation disorder. People with FAODs cannot properly break down fat from either the food they eat or from fat stored in their bodies.
The symptoms and treatment vary between different FAODs. They can also vary from person to person with the same FAOD. See the fact sheets for each specific FAOD.
FAODs are inherited in an autosomal recessive manner and affect both males and females.
WHAT CAUSES SCHADD?
SCHADD is caused by problems with the enzyme “short chain 3-hydroxyacyl CoA dehydrogenase” (SCHAD). In people with M/SHADD, the SCHAD enzyme is either missing or not working properly. This enzyme’s job is to help change certain fats in the food we eat into energy for the body. It also helps us use fat already stored in the body.
Energy from fat keeps us going whenever our bodies run low of their main source of energy, a type of sugar called This 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.. Our bodies rely on fat when we don’t eat for a stretch of time – like when we miss a meal or when we sleep.
Some people with SCHADD cannot break down fat for energy. Most babies found to have SCHADD on newborn The 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. do not seem to have this problem and do not develop symptoms.
IF SCHADD IS NOT TREATED, WHAT PROBLEMS OCCUR?
The symptoms of SCHADD are highly variable and not well understood. Things that cause stress, such as lack of sleep, lack of food, illness, or infection are thought to trigger episodes of illness called metabolic crises in some children with SCHADD but not in others.
Some of the first symptoms of a This 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. are:
- extreme sleepiness
- behavior changes
- irritable mood
- poor appetite
Other symptoms then follow:
- low blood sugar, called This 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.
If a metabolic crisis is not treated, a child with SCHADD can develop:
- breathing problems
- These 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.
- swelling of the brain
- This 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., sometimes leading to death
Other effects of SCHADD can include:
- irregular heart beat and other heart problems
- enlarged heart
- liver problems
- muscle problems
- high levels of insulin in the blood in some babies
WHAT IS THE TREATMENT FOR SCHADD?
Your baby’s primary doctor may work with a metabolic doctor to care for your child. Your doctor may also suggest that you meet with a This 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. familiar with SCHADD.
Certain treatments may be advised for some children but not others. When necessary, treatment is usually needed throughout life. The following are treatments that may be recommended for some children with SCHADD:
1. Avoid going a long time without food
Some infants and young children with SCHADD may need to eat frequently to prevent a metabolic crisis. Your metabolic doctor will tell you how often your child needs to be fed. In general, it is often suggested that infants that need to avoid fasting be fed every four to six hours. Some babies may need to eat even more frequently than this. It is important that these infants be fed during the night. If needed, your metabolic doctor and dietician will give you an appropriate feeding plan for your infant. Your doctor may also give you a ‘sick day’ plan tailored to your child’s needs for you to follow during illnesses or other times when your child will not eat.
Sometimes a low fat, high carbohydrate food plan is recommended. This 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. give the body many types of sugar that can be used as energy. In fact, for children needing this treatment, most food in the diet should be carbohydrates (bread, pasta, fruit, vegetables, etc.) and A 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. (lean meat and low-fat dairy foods). Any diet changes should be made under the guidance of a dietician familiar with SCHADD.
Ask your doctor whether your child needs to have any changes in his or her diet.
3. This 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. supplements and other medications
Some children may be helped by taking L-carnitine. This is a safe and natural substance that helps the body create energy. It also helps the body get rid of harmful wastes. Your doctor will decide whether your child needs L-carnitine. Unless you are advised otherwise, use only L-carnitine prescribed by your doctor.
Babies with high This is a hormone made in the pancreas. It controls the level of glucose (sugar) in the blood. levels may need medication. Your doctor will let you know if your child needs to take medication for this.
Do not use any medications or supplements without checking with your doctor.
4. Call your doctor at the start of any illness
If your child has shown previous symptoms of SCHADD, always call your health care provider when he or she has any of the following:
- poor appetite
- low energy or excessive sleepiness
- an infection
- a fever
- persistent muscle pain or weakness
Children who have had symptoms of SCHADD need to eat extra starchy food and drink more fluids during any illness – even if they may not feel hungry – or they could develop a metabolic crisis. Children who are sick often don’t want to eat. If they won’t or can’t eat, children with symptoms of SCHADD may need to be treated in the hospital to prevent problems.
Ask your metabolic doctor if you should carry a special travel letter with medical instructions for your child’s care.
WHAT HAPPENS WHEN SCHADD IS TREATED?
It is not known how effective treatment is in preventing health problems. It is hoped that with prompt and careful treatment, children with SCHADD will be able to live healthy lives with typical growth and development.
The goal of treatment is to prevent death and serious health problems. However, children who have repeated episodes of hypoglycemia or metabolic crisis may develop brain damage. This can result in learning problems, intellectual disabilities, or other lifelong effects.
WHAT CAUSES THE SCHAD ENZYME TO BE ABSENT OR NOT WORKING CORRECTLY?
A 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. tell the body how to make enzymes. The HADH gene instructs the body to make the SCHAD enzyme. Everyone has two copies of the HADH gene. People with SCHADD have changes, also called A 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., in both copies of their HADH genes that cause them to not work correctly. Because of the variants in the HADH genes, the SCHAD enzyme either does not work properly or is not made at all.
HOW IS SCHADD INHERITED?
SCHADD is inherited in an Most 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. manner. It affects both boys and girls equally.
Everyone has two copies of the HADH gene that make the SCHAD enzyme. In children with SCHADD, neither of these HADH genes works correctly. These children inherit one non-working HADH gene from each parent.
Parents of children with SCHADD rarely have the disorder. Instead, each parent has a single non-working HADH gene for SCHADD. They are called A 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.. Carriers do not have SCHADD because their other HADH gene is working correctly.
When both parents are carriers, there is a 25% chance in each pregnancy for the child to have SCHADD. There is a 50% chance for the child to be a carrier, just like the parents. And, there is a 25% chance for the child to have two working genes.
Genetic 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. is available to families who have children with SCHADD. These 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. can answer your questions about how SCHADD is inherited, choices during future pregnancies, and how to test other family members. Ask your doctor about a referral to a Relating to (or due to) genes and heredity or the field of studying genes and heredity. counselor.
IS GENETIC TESTING AVAILABLE?
Genetic testing for SCHADD may be available. Genetic testing, also called 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. testing, looks for changes (variants) in the HADH genes that cause SCHADD. Ask your metabolic doctor or genetic counselor about genetic testing for SCHADD.
DNA testing is not necessary to diagnose your child. It can be helpful for carrier testing or prenatal diagnosis, discussed below.
WHAT OTHER TESTING IS AVAILABLE?
SCHADD can be confirmed by a special test called a “This 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.” using a skin sample. Talk to your doctor or your genetic counselor if you have questions about testing for SCHADD.
CAN YOU TEST DURING A FUTURE PREGNANCY?
It may be possible to test for SCHADD during pregnancy either by DNA testing or through a special test called a “fatty acid oxidation probe” using The 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. from the fetus. The sample needed for these tests is obtained by either 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. or This 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..
Parents can either choose to have testing during pregnancy or wait until birth to have the baby tested. Parents may also choose to use assisted reproductive techniques to decrease the chance that their future children would have SCHADD. A genetic counselor can talk to you about your choices and answer other questions you may have about prenatal testing or testing your baby after birth
CAN OTHER MEMBERS OF THE FAMILY HAVE SCHADD OR BE CARRIERS?
The brothers and sisters of a baby with SCHADD have a small chance of having this condition, even if they haven’t had symptoms. Finding out whether other children in the family have M/SCHADD may be important because early treatment may prevent serious health problems. Talk to your doctor or genetic counselor about testing your other children for SCHADD.
Brothers and sisters who do not have SCHADD still have a chance to be carriers like their parents. Except in special cases, carrier testing should only be done in people over 18 years of age.
If you are a parent of a child with SCHADD, your brothers and sisters have a 50% chance to be a M/SCHADD carrier. It is important for other family members to be told that they could be carriers. There is a very small chance they are also at risk to have children with SCHADD.
Some states do not offer newborn screening for SCHADD. However, expanded newborn screening through private labs is available for babies born in states that do not screen for SCHADD. Your healthcare provider or genetic counselor can help you obtain expanded newborn screening.
When both parents are SCHADD carriers, newborn screening results are not sufficient to rule out SCHADD in a newborn baby. In this case, special diagnostic testing should be done in addition to newborn screening.
During pregnancy, women carrying fetuses with SCHADD may be at increased risk to develop serious medical problems. Some women carrying fetuses with Fatty Acid Oxidation Disorders have developed:
- excessive vomiting
- abdominal pain
- high blood pressure
- This is a yellow color to the skin and whites of the eyes. It is often a sign of liver damage.
- abnormal fat storage in the liver
- severe bleeding
All women with a family history of SCHADD should share this information with their obstetricians and other health care providers before and during any future pregnancies. Knowing about these risks allows better medical care and early treatment if needed.
CAN OTHER FAMILY MEMBERS BE TESTED?
Brothers and sisters can be tested for SCHADD by DNA testing using a blood sample.
Carrier testing for SCHADD may be available. Ask your metabolic doctor or genetic counseling whether carrier testing is possible.
HOW MANY PEOPLE HAVE SCHADD?
SCHADD is very rare. The actual incidence is unknown.
DOES SCHADD HAPPEN MORE OFTEN IN A CERTAIN ETHNIC GROUP?
SCHADD does not happen more often in any specific race, ethnic group, geographical area, or country.
DOES SCHADD GO BY ANY OTHER NAMES?
SCHADD is sometimes also called:
- SCHAD deficiency
- HADHSC deficiency
- HADH deficiency
- HAD deficiency
- L-3-alpha-hydroxyacyl-CoA dehydrogenase, short chain, deficiency
WHERE CAN I FIND MORE INFORMATION?
Fatty Oxidation Disorders (FOD) Family Support Group
Organic Acidemia Association
United Mitochondrial Disease Foundation
Metabolic Support UK
Baby’s First Test
|Reviewed by:||HI, CA, OR, and WA metabolic specialists|
|Review date:||September 31, 2007
April 2, 2011
July 13, 2013
May 18, 2020
March 1, 2023
|Update on:||March 1, 2023|
THIS INFORMATION DOES NOT PROVIDE MEDICAL ADVICE. All content (“Content”), including text, graphics, images and information are for general informational purposes only. You are encouraged to confer with your doctor or other health care professional with regard to information contained on this information sheet. After reading this information sheet, you are encouraged to review the information carefully with your doctor or other healthcare provider. The Content is not intended to be a substitute for professional medical advice, diagnosis or treatment. NEVER DISREGARD PROFESSIONAL MEDICAL ADVICE, OR DELAY IN SEEKING IT, BECAUSE OF SOMETHING YOU HAVE READ ON THIS INFORMATION SHEET. This project is supported by a grant from the Having to do with the mother. and Child Health Bureau, Health Resources and Service Administration, Genetic Services Branch, MCH Project #:UH7MC30774-01-00 http://mchb.hrsa.gov