Isobutyryl-CoA dehydrogenase (IBCD) deficiency
IBCD deficiency is inherited in an autosomal recessive pattern. Normally a person has two functional ACAD8 genes. In people with IBCD, both genes have a mutation and there is a deficiency of the critical enzyme activity. Each parent of a newborn with IBCD deficiency typically has one functional and one mutated gene and is considered a carrier. When both parents are carriers, the chance of a newborn inheriting two mutated genes is 25%.
None known
Because this disorder is so rare, the symptoms are not well defined. Most patients never develop symptoms. A single patient had anemia (low iron levels) and cardiomyopathy (heart muscle disease). Other patients have had delayed speech development.
- Incidence: IBCD deficiency is very rare. There are less than 20 patients reported in the literature.
- New York State Method of Screening (First Tier): Screening for IBCD deficiency is accomplished by measuring the acylcarnitine C4 by tandem mass spectrometry (MS/MS).
- Second Tier Screening: None
- Testing can be affected by: Newborn screening cannot distinguish between IBCD deficiency and short-chain acyl-CoA dehydrogenase (SCAD) deficiency.
- Interpretation/reporting of data: Results are reported as within acceptable limits, borderline or as a referral. A repeat specimen should be collected for a borderline result. Prompt consultation with a specialist is required for a referral.
- Referral to Specialty Care Center: Patients with an abnormal newborn screen for IBCD deficiency are referred to an Inherited Metabolic Disorder Specialty Care Center for evaluation by a biochemical geneticist trained in the diagnosis and treatment of IBCD deficiency.
Diagnostic testing may include urine organic acid analysis and an acylcarnitine profile.
There are no established treatment protocols.
Prognosis is not well known because IBCD deficiency is rare.
Isobutyryl-CoA dehydrogenase (IBCD) deficiency is a disorder of organic acid metabolism (inherited metabolic disorder).
Multiple steps in the body are required to break down valine, a component of protein. The ACAD8 gene provides instructions for an important enzyme in this process. If there is a mutation in ACAD8, the enzyme does not function and valine is not broken down. Toxic metabolites accumulate and may cause symptoms.