Galactosemia (GALT deficiency)
Disorder Name: Galactosemia
Acronym: GALT deficiency
- What is galactosemia?
- What causes galactosemia?
- If galactosemia is not treated, what problems occur?
- What is the treatment for galactosemia?
- What happens when galactosemia is treated?
- What causes the GALT enzyme to be absent or not working correctly?
- How is Galactosemia inherited?
- Is genetic testing available?
- What other testing is available?
- Can you test during a future pregnancy?
- Can other members of the family have galactosemia or be carriers?
- Can other family members be tested?
- How many people have galactosemia?
- Does galactosemia happen more often in a certain ethnic group?
- Does galactosemia go by any other names?
- Where can I find more information?
This fact sheet has general information about galactosemia. Every child is different and some of these facts may not apply to your child specifically. Certain treatments may be advised for some children but not others. All children with galactosemia should be followed by a metabolic doctor in addition to their primary care provider.
If your newborn has had a ‘presumptive positive screen for galactosemia’ as a result of 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., it does not yet mean that he or she has galactosemia. There are other tests that need to be done to confirm whether your baby actually has galactosemia. Some babies are found not to have galactosemia and do not need treatment. Others are found to have a milder condition called “Duarte galactosemia.” Many children with Duarte galactosemia do not need treatment. Blood and urine tests can be done to determine whether your child has classic or Duarte galactosemia.
This fact sheet contains information about classic galactosemia only. Therefore, the details below are relevant only to babies who have been confirmed to have classic galactosemia. It does not contain information on Duarte galactosemia or other 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..
WHAT IS GALACTOSEMIA?
Galactosemia, which means “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. in the blood,” is a rare inheritedAcquiring a trait from one’s parents. Most traits, such as eye color or hair color, are inherited from a parent through genes. condition. People with galactosemia have problems digesting a type of sugar called galactose from the food they eat. Because they cannot break galactose down properly, it builds up in their blood. Galactose is found in milk and all foods that contain milk.
WHAT CAUSES GALACTOSEMIA?
In order for the body to use different types of carbohydratesThis 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. and sugars from the foods we eat, special enzymes break them down into smaller sugar molecules called 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., which the body uses for fuel.
Lactose, also called ‘milk sugar,’ is the main type of sugar found in milk and milk products. It is made of one molecule of galactose and one molecule of glucose. Thus, all lactose, and all milk and milk products, contain galactose. During digestion, lactose is broken down to galactose and glucose. Then galactose is further changed by the body into glucose so it can be used as energy.
Galactosemia is caused by problems with the enzyme ‘galactose-1-phosphate uridyl transferase’ (GALT). In people with galactosemia, the GALT enzyme is either missing or not working properly. This enzyme’s job is to change galactose into glucose. When the GALT enzyme is missing or not working properly, galactose cannot be changed to glucose so it builds up in the blood in large amounts. Unless treated, the excess galactose will affect many parts of the body and, over time, may be life-threatening.
Galactosemia occurs when babies do not have enough of the GALT enzyme. Babies start showing health effects within days of feeding on breast milk or milk-containing formulas. Virtually all cases of classic galactosemia can be detected by newborn 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..
IF GALACTOSEMIA IS NOT TREATED, WHAT PROBLEMS OCCUR?
Excess galactose in the blood affects many parts of the body. Some of the organs that may be affected include the brain, eyes, liver, and kidneys.
Infants with galactosemia usually have diarrhea and vomiting within a few days of drinking milk or formula containing lactose.
Some of the other early effects of untreated galactosemia include:
- Failure to gain weight or grow in length
- Poor feeding and poor suck
- LethargyAbnormal drowsiness.
If treatment is not started, other symptoms are likely to follow:
- Low blood sugar, called 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.
- 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.
- Enlarged liver that does not work properly
- Jaundice (yellow color to the skin or whites of the eyes)
- Serious blood infections that could lead to 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. and death
- Early cataracts which occur in about 10% of children
Some untreated babies have high levels of ammoniaThis 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., a toxic substance, in their blood. High ammonia levels and hypoglycemia can both lead to 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. and, if not treated, can cause death.
Most untreated children eventually die of liver failure. Surviving babies who remain untreated may have intellectual disabilities and other damage to the brain and nervous system.
Even with adequate treatment, individuals with galactosemia may develop one or more of the following:
- Early 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.
- Mild intellectual disabilities or learning delays
- Ataxia (unsteady gait)
- Delays in growth
- Speech problems and delays
Most girls with galactosemia will have delayed periods or do not get their periods at all. Some women with galactosemia start menopause early or have ‘premature ovarian failure’ in which the ovaries stop releasing eggs earlier than normal menopause.
WHAT IS THE TREATMENT FOR GALACTOSEMIA?
Your baby’s primary doctor will work with a 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. and a 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. familiar with galactosemia to care for your child.
Prompt treatment is needed to prevent serious health problems and intellectual disabilities. Babies with galactosemia who do not start treatment shortly after birth may have permanent effects.
Infants and children who are either missing the GALT enzyme completely or who have less than 10% of the normal amount of enzyme must follow a special food plan. They need to avoid all foods with lactose and galactose. All milk and milk products must be replaced with formula that contains no lactose.
The following are treatments often advised for children with classic galactosemia:
1. Lactose and galactose-free diet
People with classic galactosemia are encouraged to follow a lactose and galactose-free food plan throughout life. Lactose or galactose are found in the following foods, all of which must be avoided:
- Milk and all dairy products
- Processed and pre-packaged foods often contain lactose
- Tomato sauces
- Some candies
- Certain medications – tablets, capsules, sweetened liquid drops that contain lactose as a filler
- Some fruits and vegetables also contain galactose
- Any foods or drugs which contain the ingredients lactulose, casein, caseinate, lactalbumin, curds, whey, or whey solids
Your dietitian will help you develop a food plan that allows your child to avoid lactose and galactose while still eating the right amount of 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., nutrients, and energy to keep him or her healthy.
Your child’s food plan will depend on many things such as his or her age, weight, general health, and blood test results. Your dietician will fine-tune your child’s diet over time. The special food plan should be continued throughout life.
2. Special lactose-free formula
Newborns with galactosemia are given a special formula free of lactose. The most common formulas used for babies with galactosemia are those made with soy protein isolate. Soy milk itself contains galactose and should not be used.
Your metabolic doctor and dietitian will tell you what type of formula is best and how much to use. Some states offer help with payment for this formula and others require private insurance coverage for the formula and other special medical foods.
3. Calcium supplements
Since children with galactosemia are not eating milk products, calcium intake may be too low. This may cause their bones to be weaker than average (osteopenia). Therefore, children with galactosemia are often advised to take calcium supplements to ensure they receive enough calcium each day.
Some doctors also advise 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. and Vitamin K supplements in addition to calcium.
Your doctor will tell you what supplements to give your child and how much. Do not use any medication or supplement without checking with your doctor.
4. Monitoring health
Babies and young children with galactosemia usually need regular blood and urine tests. These tests are used to detect toxic substances made when galactosemia is not in good control. The test results will help your doctors and dietitian fine-tune the treatment to meet your child’s needs.
Your doctor may also suggest a formal evaluation of your child’s mental development and his or her speech and language skills. If your child shows delays in certain areas of learning or speech, extra help can be arranged. Early intervention programs are available in most states to provide services before children reach school age.
Monitoring for other health problems associated with galactosemia such as cataracts, bone problems, and premature ovarian failureThis 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. may also be done.
5. Informing friends, relatives, teachers, and child-care providers
It is important for you to tell everyone who helps care for your child that he or she cannot eat or drink milk-containing foods. A Medic-Alert bracelet that states your child’s food restrictions can be helpful. In addition, your doctor may advise you to carry an emergency treatment letter with steps for your child’s care.
WHAT HAPPENS WHEN GALACTOSEMIA IS TREATED?
Because the body also makes some galactose, symptoms cannot be completely avoided by removing all lactose and galactose from the diet. Researchers are working on finding a treatment to lower the amount of galactose made by the body, but there is no effective method to do so at this time.
When treatment starts before a baby is 10 days old, there is a much better chance for normal growth, development, and intelligence. Some children who receive early treatment may have delays in growth, but most attain normal adult heights.
Even with careful treatment from an early age, some children with classic galactosemia show delays in learning and development and may need extra help in school. Some children develop speech and language delays. Some have delays in motor skills such as walking and coordination and balance problems.
Even when carefully treated, girls with galactosemia have a higher chance of having delayed periods and having premature ovarian failure.
If treatment is started after 10 days of life, delays or learning problems are more likely. The level of delay varies from child to child. Treatment is still important, even if started late, because it can help prevent further delays and symptoms.
WHAT CAUSES THE GALT ENZYME TO BE ABSENT OR NOT WORKING CORRECTLY?
Genes tell the body how to make enzymesA 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.. The GALT gene instructs the body to make the GALT enzyme. Everyone has two copies of the GALT gene. People with galactosmia have changes, also called variants, in both copies of their GALT genesA 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.. Because of the variants in the GALT genes, the GALT enzyme either does not work properly or is not made at all.
HOW IS GALACTOSEMIA INHERITED?
Galactosemia is inherited in an autosomal recessive manner. It affects both boys and girls equally.
Everyone has two copies of the GALT gene that make the GALT enzyme. In children with galactosemia, neither of their GALT genes works correctly. These children inherit one non-working GALT gene from each parent.
Parents of children with galactosemia rarely have the condition themselves. Instead, each parent has a single non-working GALT gene for galactosemia. They are called carriersA 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 galactosemia because the other GALT gene is working correctly.
When both parents are carriers, there is a 25% chance in each pregnancy for the child to have galactosemia. 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.
GeneticRelating to (or due to) genes and heredity or the field of studying genes and heredity. counseling is available to families who have children with galactosemia. Genetic counselors can answer your questions about how galactosemia is inherited, choices during future pregnancies, and how to test other family members. Ask your doctor about a referral to a 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..
IS GENETIC TESTING AVAILABLE?
Genetic testing for galactosemia can be done on a blood sample. Genetic testing, also called DNA testing, looks for changes in the GALT genes that causes galactosemia. Over 99% of the time, DNADeoxyribonucleic 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 can identify the variants in the GALT genes in a child with this condition.
DNA testing is not necessary to diagnose your child. However, it may be helpful in determining what type of galactosemia your child has.
WHAT OTHER TESTING IS AVAILABLE?
If your child has had a positive screen for galactosemia through a newborn screening program, other tests still need to be done in order to confirm the diagnosis. One of these special tests detects the amount of GALT enzyme present in red blood cellsRed blood cells are the major component in blood that delivers oxygen from the lungs to the body tissues. and is often used to confirm galactosemia.
Other blood or urine tests may be helpful to determine whether your child needs treatment or whether treatment is working properly. Ask your doctor if you have any questions about testing for galactosemia.
CAN YOU TEST DURING A FUTURE PREGNANCY?
If both gene changes (variants) have been found in your child with galactosemia, DNA testing can be done during any future pregnancies. If DNA testing is not helpful, an enzyme test using cellsThe 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 can be done during pregnancy. The sample needed for this test is obtained by either CVS or 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..
Parents may 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 galactosemia. A genetic counselor can talk to you about your choices and answer questions about prenatal testing or testing your baby after birth.
If you do not have prenatal diagnosis during your next pregnancies, you should feed your newborn with the recommended formulas instead of breast milk or regular formula until the results of newborn screening or additional diagnostic tests have been completed.
CAN OTHER MEMBERS OF THE FAMILY HAVE GALACTOSEMIA OR BE CARRIERS?
If they are healthy and show typical development, older brothers and sisters of a baby with galactosemia are unlikely to have the condition. Talk to your doctor or genetic counselor if you have questions about your other children.
Brothers and sisters who do not have galactosemia still have a 2/3rds 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 galactosemia, your brothers and sisters have a 50% chance to be a carrier. It is important for other family members to be told that they could be carriers. There is a small chance they are also at risk to have children with galactosemia.
All 50 US states offer newborn screening for galactosemia. Newborn screening can detect virtually all babies with classic galactosemia. However, in families in which a child has mild galactosemia, newborn screening results are not sufficient to rule out this condition in future siblings. In newborns who have a 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. with mild galactosemia, special diagnostic testing is recommended in addition to newborn screening.
CAN OTHER FAMILY MEMBERS BE TESTED?
If there is concern about whether they have galactosemia, your other children can be tested. Talk to your doctor or genetic counselor if you have questions about testing for galactosemia.
If both gene changes (variants) have been found in your child, other adult family members can have DNA testing to see if they are carriers.
If DNA testing is not helpful, other methods of carrier testing may be available. If you have questions about carrier testing, ask your genetic counselor or metabolic doctor.
HOW MANY PEOPLE HAVE GALACTOSEMIA?
About one in every 48,000 babies in the United States is born with galactosemia.
DOES GALACTOSEMIA HAPPEN MORE OFTEN IN A CERTAIN ETHNIC GROUP?
Galactosemia occurs in people of all ethnic groups around the world. It is more common in people from Ireland. One in 16,500 Irish babies is born with this condition.
DOES GALACTOSEMIA GO BY ANY OTHER NAMES?
Galactosemia is sometimes also called:
- Galactose-1-phosphate uridyl transferase deficiency
- GALT deficiency
Variants of classic GALT that are not discussed in this fact sheet include:
- Galactokinase deficiency
- UDP-galactose 4-epimerase deficiency (GALE)
WHERE CAN I FIND MORE INFORMATION?
The Galactosemia Foundation
Metabolic Support UK
Baby’s First Test
|Reviewed by:||HI, CA, OR, and WA metabolic specialists|
|Review date:||November 30, 2012
August 28, 2016
June 8, 2020
March 20, 2023
|Update on:||March 20, 2023|
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