Children and Youth with Special Health Needs (CYSHN)
Short chain acyl-CoA dehydrogenase deficiency (SCAD)
On this page...
- What is SCAD?
- What causes SCAD?
- What causes the SCAD enzyme to be absent or not working correctly?
- How is SCAD inherited?
- Is genetic testing available?
- What other testing is available?
- Can you test during pregnancy?
- Can other members of the family have SCAD or be carriers?
- Can other family members be tested?
- How many people have SCAD?
- Does SCAD happen more often in a certain ethnic group?
- Does SCAD go by any other names?
- What is the treatment for SCAD?
- What happens when SCAD is treated?
- If SCAD is not treated, what problems occur?
This fact sheet contains general information on SCAD. Every child with SCAD is different and some of this information may not apply to your child specifically. Not all is known about SCAD and, at present, there is no standard treatment plan. Certain treatments may be recommended for some children but not others. Children with SCAD should be followed by a metabolic doctor in addition to their primary doctor.
What is SCAD?
SCAD stands for “short chain acyl-CoA dehydrogenase deficiency”. It is one type of fatty acid oxidation disorder. Some people with SCAD cannot break down fat into energy for the body. However, most babies with newborn screening results showing SCAD never have symptoms.
Fatty Acid Oxidation Disorders:
Fatty acid oxidation disorders (FAODs) are a group of rare inherited conditions. They are caused by enzymes that do not work properly.
A number of enzymes 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 SCAD?
SCAD occurs when an enzyme, called “short chain acyl-CoA dehydrogenase” (SCAD) is either missing or not working properly. This enzyme's job is to break down certain fats from the food we eat into energy. It also breaks down 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 glucose. 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 SCAD cannot properly break down fat for energy. However, most people with SCAD do not seem to have this problem and do not ever develop symptoms.
What causes the SCAD enzyme to be absent or not working properly?
Genes tell the body to make various enzymes. People with SCAD have a pair of genes that do not work correctly. Because of the changes in this pair of genes, the SCAD enzyme may not work properly or may not be made at all. Only a small number of babies found to have SCAD through newborn screening will actually have symptoms.
How is SCAD inherited?
SCAD is inherited in an autosomal recessive manner. It affects both boys and girls equally.
Everyone has a pair of genes that make the SCAD enzyme. In children with SCAD, neither of these genes works correctly. These children inherit one non-working gene for the condition from each parent.Parents of children with SCAD rarely have the disorder. Instead, each parent has a single non-working gene for SCAD. They are called carriers. Carriers do not have SCAD 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 SCAD. 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 SCAD. Genetic counselors can answer your questions about how SCAD 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 SCAD may be available. Genetic testing, also called DNA testing, looks for changes in the pair of genes that cause SCAD. In some affected children, both gene changes can be found. However, in other children, neither or only one of the two gene changes can be found, even though we know they are present.
DNA testing is not necessary to diagnose your child. It can be helpful for carrier testing or prenatal diagnosis, discussed below. Talk with your metabolic doctor or genetic counselor if you have questions about DNA testing for SCAD.
What other testing is available?
SCAD can be confirmed by an enzyme test using a blood or skin sample. Talk to your doctor or your genetic counselor if you have questions about testing for SCAD.
Can you test during pregnancy?
If both gene changes have been found in your child with SCAD, 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, testing during pregnancy can be attempted by performing an enzyme test on fetal cells. Again, the sample needed for these tests is obtained by either CVS or amniocentesis.
Parents may either choose to have testing during pregnancy or wait until birth. A genetic counselor can talk to you about your choices and answer other questions about prenatal testing or testing your baby after birth
The brothers and sisters of an affected baby have a chance of having SCAD, even if they haven't had symptoms. Talk with your doctor or genetic counselor about testing your other children for SCAD.
Brothers and sisters who do not have SCAD 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 an SCAD 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 SCAD.
When both parents are carriers, newborn screening results are not sufficient to rule out SCAD in a newborn baby. In this case, special diagnostic testing should be done in addition to newborn screening.
During pregnancy, women carrying fetuses with SCAD 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
- abnormal fat storage in the liver
- severe bleeding
All women with a family history of SCAD 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 SCAD using a blood or skin sample.
If both gene changes have been found in your child with SCAD, 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 SCAD?
SCAD is thought to be very rare. The actual incidence is unknown.
Does SCAD happen more frequently in a certain ethnic group?
SCAD does not happen more often in any specific race, ethnic group, geographical area or country.
Does SCAD go by any other names?
SCAD is also sometimes called:
- ACADS deficiency
- SCADH deficiency
What is the treatment for SCAD?
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 dietician familiar with SCAD.
Certain treatments may be advised for some children but not others. Babies found to have SCAD on newborn screening, but who have not shown any effects, may not need treatment. When necessary, treatment is usually needed throughout life. The following are treatments recommended for some, but not all, children with SCAD:
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, most teens and adults with SCAD can go without food for up to 12 hours. People who have had symptoms may need to continue the other treatments throughout life.
Ask your doctor whether or not your child needs to have any changes in his or her diet.
L-Carnitine and Riboflavin
Do not use any medications or supplements without checking with your doctor.
Call your doctor at the start of any illness
Some children with SCAD may need to eat extra starchy food and drink more fluids during an illness - even if they may not feel hungry - to prevent a metabolic crisis. Children who are sick often don't want to eat. If they won't or can't eat, some children with SCAD may need to be treated in the hospital to prevent problems. If needed, your doctor will give you a ‘sick day’ plan for you to follow during illness or other times when your child will not eat.
It is not known how effective treatment is in preventing problems. Treatment may help prevent or control symptoms in some children. Children who need treatment and are treated early may be able to live healthy lives with typical growth and development. Some children, though, may continue to have learning delays, muscle weakness and other health problems despite treatment.
If SCAD is not treated, what problems occur?
SCAD is highly variable and not well understood. Most babies found to have SCAD through newborn screening never have symptoms. In fact, so far, there have been only about 20 people with SCAD reported to have health effects. Things that cause stress, such as lack of sleep, going without food for too long, illness, or infection are thought to trigger episodes of illness called metabolic crisis in some children but not others.
For the small number of people with SCAD who show effects, the condition occurs in two different forms: one found in infants, the other found in adults.
SCAD in infants
This type of SCAD is found in newborns and infants. Symptoms, when they happen, often start between the first week and 3 months of life.
Some of the first symptoms of a metabolic crisis are:
- extreme sleepiness
- behavior changes
- irritable mood
- poor appetite
Other symptoms then follow:
- increased levels of acidic substances in the blood, called metabolic acidosis
If a metabolic crisis is not treated, a child with SCAD can develop:
- breathing problems
- coma, sometimes leading to death
Other effects of SCAD seen in some infants and children:
- poor weight gain
- delays in learning
- delays in walking and other motor skills
- low muscle tone
- muscle weakness or muscle tightness
- enlarged liver
- enlarged spleen
Symptoms of a metabolic crisis often happen after having nothing to eat for more than a few hours. Symptoms are also more likely when a child with SCAD gets sick or has an infection.
Many children with this condition have never had any effects and may only be found to have SCAD after a brother or sister has been diagnosed.
SCAD in adults
The second type of SCAD is found in adults. The adult form of SCAD affects just the muscles. It can cause ongoing muscle problems, pain and weakness. Adults with SCAD can also have episodes of nausea, vomiting and shortness of breath. The muscle problems often get worse after heavy exercise or exertion.
Minnesota Family Support for Fatty Acid Oxidation Disorder (FAOD) Contact: email@example.com
Medically Prescribed Formula: a table that provides a list of commonly prescribed medical foods and formulas and /or medication for this disorder.http://www.fodsupport.org
Organic Acidemia Association
United Mitochondrial Disease Foundation
Children Living with Inherited Metabolic Diseases (CLIMB)
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, 01-Aug-2012 13:57:50 CDT|