Children and Youth with Special Health Needs (CYSHN)
Glutaric acidemia, type 1 (GA-1)
On this page...
- What is GA-1?
- What causes GA-1?
- What causes the glutaryl-CoA dehydrogenase enzyme to be absent or not working correctly?
- How is GA-1 inherited?
- Is genetic testing available?
- What other testing is available?
- Can you test during pregnancy?
- Can other members of the family have GA-1 or be carriers?
- Can other family members be tested?
- How many people have GA-1?
- Does GA-1 happen more often in a certain ethnic group?
- Does GA-1 go by any other names?
- What is the treatment for GA-1?
- What happens when GA-1 is treated?
- If GA-1 is not treated, what problems occur?
This fact sheet contains general information about GA-1. Every child is different and some of these facts may not apply to your child specifically. Certain treatments may be recommended for some children but not others. All children with GA-1 should be followed by a metabolic doctor in addition to their primary doctor.
What is GA-1?
GA-1 stands for "glutaric acidemia, type 1". It is one type of organic acid disorder. People with GA-1 have problems breaking down the amino acids lysine, and tryptophan from the food they eat.
Organic Acid Disorders:
Organic acid disorders (OAs) are a group of rare inherited conditions. They are caused by enzymes that do not work properly. A number of enzymes are needed to process protein from the food we eat for use by the body. Problems with one or more of these enzymes can cause an organic acid disorder.
People with organic acid disorders cannot break down protein properly. This causes harmful substances to build up in their blood and urine. These substances can affect health, growth and learning.
The symptoms and treatment vary between different organic acid disorders. They can also vary from person to person with the same organic acid disorder. See the fact sheets for each specific organic acid disorder.
Organic acid disorders are inherited in an autosomal recessive manner and affect both males and females.
What causes GA-1?
In order for the body to use protein from the food we eat, it is broken down into smaller parts called amino acids. Special enzymes then make changes to the amino acids so the body can use them.
GA-1 occurs when an enzyme called "glutaryl-CoA dehydrogenase" is either missing or not working properly. This enzyme's job is to break down a substance called glutaryl-CoA. Glutaryl-CoA is made when the amino acids lysine, hydroxylysine and tryptophan are processed. It cannot be removed and it causes glutaric acid and other harmful substances build up in the blood and cause problems. Lysine and tryptophan are found in all foods that contain protein.
What causes the glutaryl-CoA dehydrogenase enzyme to be absent or not working correctly?
Genes tell the body to make various enzymes. People with GA-1 have a pair of genes that do not work correctly. Because of the changes in this pair of genes, the glutaryl-CoA dehydrogenase enzyme either does not work properly or is not made at all.
How is GA-1 inherited?
GA-1 is in an autosomal recessive manner. It affects both boys and girls equally.
Everyone has a pair of genes that make the glutaryl-CoA dehydrogenase enzyme. In children with GA-1, neither of these genes works correctly. These children inherit one non-working gene for the condition from each parent.Parents of children with GA-1 rarely have the condition themselves. Instead, each parent has a single non-working gene for GA-1. They are called carriers. Carriers do not have GA-1 because the other gene of this pair is working correctly.
When both parents are carriers, there is a 25% chance in each pregnancy for the child to have GA-1. 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 is available to families who have children with GA-1. Genetic counselors can answer your questions about how the condition is inherited, choices during future pregnancies, and how to test other family members. Ask your doctor about a referral to a genetic counselor.
Is genetic testing available?
Genetic testing for GA-1 can be done on a blood sample. Genetic testing, also called DNA testing, looks for changes in the pair of genes that cause GA-1.
DNA testing is not necessary to diagnose your child. It can be helpful for carrier or prenatal testing, discussed below.
Special tests on blood, urine, or skin samples can be done to confirm GA-1. Talk to your metabolic doctor or genetic counselor if you have questions about testing for GA-1.
Can you test during pregnancy?
If both gene changes have been found in your child, DNA testing can be done during future pregnancies. The sample needed for this test is obtained by either CVS or amniocentesis.
If DNA testing would not be helpful, an enzyme test can be done on cells from the fetus. The sample needed for this test is obtained by either CVS or amniocentesis.
Parents may choose to have testing during pregnancy or wait until birth to have the baby tested. A genetic counselor can talk to you about your choices and answer questions about prenatal testing or testing your baby after birth.
Can other members of the family have GA-1 or be carriers?
The brothers and sisters of a baby with GA-1 have a chance of being affected, even if they haven't had symptoms. Finding out whether other children in the family have GA-1 is important because early treatment may prevent serious health problems. Talk to your metabolic doctor or genetic counselor about testing your other children.
Brothers and sisters who do not have GA-1 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.
Each of the parents' brothers and sisters has 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 GA-1.
When both parents are carriers, newborn screening results are not sufficient to rule out GA-1 in a newborn baby. In this case, special diagnostic testing should be done in addition to newborn screening.
Can other family members be tested?
Brothers and sisters of a child with GA-1 can be tested using blood, urine or skin samples.
If both gene changes have been found in your child, other family members can have DNA testing to see if they are carriers.
If DNA testing would not be helpful, other methods of carrier testing may be available. Your metabolic doctor or genetic counselor can answer your questions about carrier testing.
How many people have GA-1?
About one in every 40,000 white babies in the United States is born with GA-1.
Does GA-1 happen more frequently in a certain ethnic group?
GA-1 occurs in people from all parts of the world. It is more common in people of Amish background in the United States, the Ojibway Indian population in Canada, and people of Swedish ancestry.
Does GA-1 go by any other names?
GA-1 is sometimes also called:
- Glutaric aciduria type 1
- Glutaryl-CoA dehydrogenase deficiency
- Dicarboxylic aminoaciduria
- Glutarate-aspartate transport defect
What is the treatment for GA-1?
Your baby's primary doctor will work with a metabolic doctor and a dietician to care for your child.
Prompt treatment is needed to prevent episodes of metabolic crisis. You need to start treatment as soon as you know your child has GA-1. Certain treatments may be advised for some children but not others. Treatment is usually needed throughout life.
The following are treatments often recommended for babies and children with GA-1:
Do not use any medication without checking with your metabolic doctor.Children with symptoms of a metabolic crisis need medical treatment right away. They often need to be treated in the hospital. During a metabolic crisis, children may be given fluids, glucose, insulin, carnitine and other medications by IV to help get rid of harmful substances in the blood. Ask your metabolic doctor if you should carry a special travel letter with medical instructions for your child's care.
Avoid going a long time without food
Your metabolic doctor will continue to advise you on how often your child should eat as he or she gets older. When they are well, many older children and adults with GA-1 can go without food for up to 12 hours without problems. They may need to continue the other treatments throughout life.
Food plan, including medical foods and formula
Low-protein (lysine and tryptophan) diet
Many vegetables and fruits have only small amounts of lysine and tryptophan and can be eaten in carefully measured amounts.
Do not remove all protein from the diet. Your child still needs a certain amount of protein for normal growth and development. Any changes in the diet should be made under the guidance of a dietician familiar with GA-1.
Medical foods and formula
A special medical formula that contains the right level of amino acids and nutrients for your child may be recommended. Your metabolic doctor and dietician will tell you whether your child should be on this formula and how much to use.
Your child's exact 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 long-term benefits of the special diet and medical foods are not yet known. However, it is important to follow the food plan as long as your doctor advises.
|4.||Regular blood tests
Your child will have regular blood tests to measure his or her amino acid levels. Urine tests may also be done. Your child's diet and medication may need to be adjusted based on blood and urine test results.
Call your doctor at the start of any illness
Children who are sick often don't want to eat. If they can't eat, or if they show signs of a metabolic crisis, they may need to be treated in the hospital. Ask your metabolic doctor if you should carry a special travel letter with medical instructions for your child's care.
What happens when GA-1 is treated?
With prompt and lifelong treatment, children with GA-1 can often live healthy lives with typical growth and learning. Early treatment can help prevent episodes of metabolic crisis and the resulting health effects.
Even with treatment, some children continue to have episodes of metabolic crisis. This can lead to brain damage and long-term problems with involuntary movements and spasticity. After age six, metabolic crises are less common.
If GA-1 is not treated, what problems occur?
Babies with GA-1 are usually healthy at birth, although many are born with a larger than average head size. Other symptoms usually start between two months and four years of age.GA-1 causes episodes of severe illness called metabolic crises.
Some of the first symptoms of a metabolic crisis are:
- poor appetite
- extreme sleepiness or lack of energy
- low muscle tone (floppy muscles and joints)
- muscle weakness
If untreated, other symptoms then follow:
- tics or spasms of the muscles
- rigid muscle contractions called spasticity
- involuntary jerking movements of the arms and legs, called dystonia
- poor coordination and balance problems
- increased levels of acidic substances in the blood, called metabolic acidosis
- swelling of the brain or blood in the brain
- coma, sometimes leading to death
Episodes of metabolic crisis are often triggered by:
- illness or infection
- going without food for long periods of time
Other effects of GA-1 that can happen even without a metabolic crisis are:
- poor growth
- enlarged liver
- low muscle tone
- progressive spasticity
- dystonia, an involuntary movement disorder
- repeated episodes of fever
- excessive sweating
- delays in walking and other motor skills
- learning delays and mental retardation
- speech problems
- brain damage
Some people have very mild or no symptoms and are only found to be affected after a brother or sister is diagnosed.
Where can I find more information?
Organic Acidemia Association
CLIMB (Children Living with Inherited Metabolic Disorders)
Save Babies through Screening Foundation
International Organization of Glutaric Acidemia
For additional genetics information and resources:
- Genetic Alliance
- Region 4 Genetics Collaborative
- Partnering with your Doctor The Medical Home Approach: A guide for families with children who have genetic conditions - The Guide is intended to be a user-friendly, hands-on tool to support families of children who have genetic conditions to move forward in obtaining and providing a medical home for their children. The guide provides definitions, examples and tools for families to use when working with the doctor to develop a medical home.
More help available from Children and Youth with Special Health Needs (CYSHN):
- Resources: Financial and Other
- Early Childhood Intervention
- Resources for Children and Families
- Youth and Young Adults - Planning for the Future
- Emergency Planning
- Medical Home
We would like to acknowledge the Star G Project. The information on the fact sheet was obtained from the Star G Project. For the most up-to-date information on the disorder please visit their web site at http://www.newbornscreening.info. Each fact sheet was extensively reviewed by family support groups, metabolic specialists across the country and the Star G steering committee.
THIS INFORMATION DOES NOT PROVIDE MEDICAL ADVICE. All 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.
|Updated Wednesday, 25-Jul-2012 16:46:52 CDT|