General Condition Information
- 2 Methylbutyrylglycinuria
- 2- methylbutyryl-CoA dehydrogenase def.
- 2-methyl butyryl-CoA dehydrogenase deficiency
- 2-methylbutyryl CoA dehydrogenase deficiency
- 2-methylbutyryl-CoA dehydrogenase deficiency
- It is unknown how many babies are born with this rare condition each year in the United States.
- This condition is more common in Hmong or Laotian babies.
What is Short/branched chain acyl-CoA dehydrogenase deficiency
Short/branched chain acyl-CoA dehydrogenase (SBCAD) deficiency is an inherited (genetic) condition. SBCAD is the name of an enzyme in your body that helps you digest a part of some proteins called isoleucine.
Without enough of this enzyme, the body has trouble digesting proteins that have isoleucine. It does not appear that this is harmful, as babies with SBCAD deficiency have very few, if any, signs and symptoms.
Newborn Screening and Follow-Up
Newborn screening for SBCAD deficiency is done using a small amount of blood collected from your baby’s heel. To learn more about this process, visit the Blood Spot Screening page.
During screening, a special machine measures how much of certain substances (called acylcarnitines) are in your baby’s blood. Your body produces these substances when it breaks down food. Babies with high levels of these substances might have SBCAD deficiency.
If your baby’s blood spot screening result for SBCAD deficiency is out-of-range, your baby’s health care provider will contact you. Together, you will discuss next steps and follow-up plans.
An out-of-range screening result does not mean that your baby definitely has the condition. It does mean that your baby needs more follow-up testing. To learn more about screening results, visit the Blood Spot Screening Results page.
Your baby may need the following tests after an out-of-range screening result:
- Blood and/or urine tests
- Genetic testing using a blood sample
You should complete any recommended follow-up testing as soon as possible. Some more serious conditions, like Isovaleric Acidemia, can have similar results on the newborn screen. Follow-up is important for helping health care providers see if your baby has SBCAD deficiency or a different health condition.
Newborn screening helps babies lead healthier lives. If your baby has an out-of-range result, follow up with your health care provider quickly. It is important to follow their instructions. In some cases, your baby’s health care provider may decide it is best to watch (monitor) your baby to decide next steps.
Most babies with SBCAD deficiency do not have signs or symptoms.
A very small number of babies will have some health problems. In these babies, signs of the condition can appear anytime from a few months of age to childhood.
Signs of the condition may include the following:
- Poor appetite
- Sleeping longer or more often
- Gets upset easily
- Floppy arms and legs (hypotonia)
- Delayed growth
- Tight muscles (spasticity)
- Developmental delays
The condition is caused by a change in the ACADSB gene. This gene gives the body instructions to make short/branched chain acyl-CoA dehydrogenase (SBCAD). SBCAD is an enzyme that helps you digest a part of some proteins called isoleucine.
Without a working ACADSB gene, your baby’s body cannot make enough SBCAD to properly break down isoleucine.
- SBCAD deficiency is usually an autosomal recessive condition. Babies inherit the condition when each parent passes down a nonworking ACADSB gene to their baby. Only babies with two nonworking ACADSB genes—one from the mom and one from the dad—have this condition.
- People with one working copy and one nonworking copy of the ACADSB gene are called carriers.
- Carriers do not have or develop the condition. However, they may pass down a nonworking copy of the gene to their children.
- If two parents are carriers of a nonworking copy of the ACADSB gene, they have a 1 in 4 chance of having a child with SBCAD deficiency.
- Carriers for SBCAD deficiency often do not know they are carriers before having a child with the condition. In most cases, families have no history of the condition until the birth of a child with SBCAD deficiency.
- Parents who already have a child with SBCAD deficiency due to a change in the ACADSB gene still have a 1 in 4 chance of having another child with SBCAD deficiency. This 1 in 4 chance stays the same for all future children.
- Genetic counselors and medical geneticists can help families learn about this condition and the chance of having children with it. Visit the National Society of Genetic Counselors to find a genetic counselor and the American College of Medical Genetics and Genomics to find a medical geneticist.
Treatment and Management
Most babies with SBCAD deficiency will not need treatment.
If your baby does have signs and symptoms of SBCAD deficiency, it is important to talk to your health care provider about which treatment(s), if any, your baby needs.