Children and Youth with Special Health Needs (CYSHN)
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- What is argininemia?
- What causes argininemia?
- What causes the arginase enzyme to be absent or not working correctly?
- How is argininemia inherited?
- Is genetic testing available?
- What other testing is available?
- Can you test during pregnancy?
- Can other members of the family have argininemia or be carriers?
- Can other family members be tested?
- How many people have argininemia?
- Does argininemia happen more often in a certain ethnic group?
- Does argininemia go by any other names?
- What is the treatment for argininemia?
- What happens when argininemia is treated?
- If argininemia is not treated, what problems occur?
This fact sheet has general information about argininemia. 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. Children with argininemia should be followed by a metabolic doctor in addition to their primary doctor.
What is argininemia?
Argininemia is one type of amino acid disorder. People with this condition have problems removing ammonia from the body. Ammonia is a harmful substance. It is made when protein and its building blocks, amino acids, are broken down for use by the body.
|Amino Acid Disorders:
Protein is made up of smaller building blocks called amino acids. A number of different enzymes are needed to process these amino acids for use by the body. Because of missing or non-working enzymes, people with amino acid disorders cannot process certain amino acids. These amino acids, along with other toxic substances, then build up in the body and cause problems.
The symptoms and treatment vary between different amino acid disorders. They can also vary from person to person with the same amino acid disorder. See the fact sheets for each specific amino acid disorder.
Amino acid disorders are inherited in an autosomal recessive manner and affect both males and females.
What causes argininemia?
Argininemia is one of a small number of conditions called “urea cycle disorders” (UCD).
It occurs when an enzyme called “arginase” is either missing or not working properly. This enzyme’s job is to help break down the amino acid arginine and to help remove ammonia from the body.
When arginase is not working, arginine, along with ammonia, can build up in the blood. This can cause serious effects on growth, learning and health.
Genes tell the body to make various enzymes. People with argininemia have a pair of genes that do not work correctly. Because of the changes in this pair of genes, the arginase enzyme either does not work properly or is not made at all.
How is argininemia inherited?
Argininemia is inherited in an autosomal recessive manner. It affects both boys and girls equally.
Everyone has a pair of genes that make the arginase enzyme. In children with argininemia, neither of these genes works correctly. These children inherit one non-working gene for the condition from each parent.
Parents of children with argininemia rarely have the disorder. Instead, each parent has a single non-working gene for argininemia. They are called carriers. Carriers do not have the condition 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 argininemia. 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 argininemia. 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 there genetic testing available?
Genetic testing for argininemia is available. Genetic testing, also called DNA testing, looks for changes in the pair of genes that cause the condition. Ask your metabolic doctor or genetic counselor whether DNA testing is available to your family.
DNA testing is not necessary to diagnose your child. However, it can be helpful for carrier testing or prenatal diagnosis, discussed below.
What other testing is available?
Special blood and urine tests can be done to confirm argininemia. Talk to your metabolic doctor if you have questions about this type of testing.
Can you test during pregnancy?
If both gene changes have been found in the child with argininemia, DNA testing can be done during future pregnancies. The sample needed for this test is obtained by either CVS or amniocentesis. CVS stands for Chorionic Villus Sampling, which is a special test done early in pregnancy. During CVS, a small sample of the placenta is removed for genetic testing.
If DNA testing is not possible, an enzyme test can be done using a blood sample from the fetus. The sample needed is obtained by a procedure called fetal blood sampling.
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 argininemia or be carriers?
If they are healthy and growing normally, older brothers and sisters of a baby with argininemia are at low risk of having the condition. However, finding out whether other children in the family have this condition may be important because early treatment may prevent serious health problems. Ask your metabolic doctor whether your other children should be tested.
Brothers and sisters who do not have argininemia 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 argininemia.
When both parents are carriers, newborn screening results are not sufficient to rule out the condition 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 argininemia can be tested using blood, urine, or skin samples.
Carrier testing may be available. Your metabolic doctor or genetic counselor can answer your questions about carrier testing.
How many people have argininemia?
About one in every 300,000 babies in the United States is born with this condition.
Does argininemia happen more often in a certain ethnic group?
Argininemia does not happen more often in any specific race, ethnic group, geographical area or country.
Does arginase deficiency go by any other names?
Argininemia is sometimes also called:
- Arginase deficiency
- ARG1 deficiency
What is the treatment for argininemia?
Your baby's primary doctor may work with a metabolic doctor and a dietician to care for your child.
Prompt treatment is needed to prevent the build-up of ammonia. You should start treatment as soon as you know your child has this condition.
The following are treatments often recommended for babies and children with argininemia:
Low-protein diet and/or special medical foods and formula
Eating foods high in protein can cause ammonia and arginine to build up in the blood, resulting in severe illness. Many vegetables and fruits have only small amounts of protein 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. Your dietician will help you create the best food plan for your child.
Medical foods and formula
Your baby may be given a special formula that contains the correct amount of nutrients and amino acids. Your metabolic doctor and dietician will decide whether your child needs this formula.
Your child’s exact food plan will depend on many things such as his or her age, weight, and general health. Your dietician will fine-tune your child’s diet over time. Any diet changes should be made under the guidance of a dietician familiar with argininemia.
There are certain medications that can help the body get rid of excess arginine and ammonia. Your metabolic doctor will decide which medications your child should take.
Your child will need to have regular blood tests to measure amino acid and ammonia levels. Your child’s diet and medication may need to be adjusted based on blood test results.
Call your doctor at the start of any illness:
Children with symptoms of high blood ammonia often 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 argininemia is treated?
With prompt and lifelong treatment, children with argininemia may be able to live healthy lives with typical growth and learning.
Even with treatment, some children still have effects from high blood levels of arginine and ammonia. This can result permanent learning problems, mental retardation or spasticity.
If argininemia is not treated, what problems occur?
The effects of this condition vary from person to person. Symptoms can start in infancy or not until later in childhood. Many children have their first symptoms around one year to three years of age. Effects in infants can include:
- poor growth
- learning delays
- poor coordination and balance problems
- fussiness or illness when fed high protein food
Episodes of illness caused by high levels of ammonia in the blood can sometimes occur but are not common. Some of the first symptoms of high blood ammonia are:
- poor appetite
- excess sleepiness or lack of energy
If untreated, other symptoms can follow:
- muscle weakness
- decreased or increased muscle tone
- breathing problems
- problems staying warm
- swelling of the brain
- coma, and sometimes death
Often, symptoms of arginase deficiency do not begin until later in infancy or childhood. Common effects in older infants and children include:
- poor growth
- small head size
- behavior problems
- learning delays
- avoidance of meat or other high protein foods
- occasional bouts of vomiting and excessive sleepiness
Episodes of high blood ammonia, described above, happen rarely. If they occur, they are more likely to happen:
- after going without food for long periods
- during illness or infection
- after high-protein meals
Where can I find more information?
Medically Prescribed Formula: a table that provides a list of commonly prescribed medical foods and formulas and /or medication for this disorder.
Partnering with your Doctor The Medical Home Approach: A guide for families with children who have genetic conditions - This 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.
National Library of Medicine Genetics Home Reference: Arginase Deficiency http://ghr.nlm.nih.gov/condition/arginase-deficiency
National Urea Cycle Disorders Foundation
CLIMB (Children Living with Inherited Metabolic Disorders)
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 16:30:02 CDT|