MCAD Deficiency

BACKGROUND:

Medium chain acyl CoA dehydrogenase (MCAD) deficiency is a potentially fatal autosomal recessive disease. It is the most commonly recognized defect of mitochondrial ß-oxidation which has been implicated in a proportion of SIDS (sudden infant death syndrome) cases as well as unexpected and sudden death in older patients. Clinical symptoms are quite heterogeneous, ranging from severe recurrent episodes of hypoglycemia (non-ketotic hypoglycemia), acute life threatening events (SIDS) to years of remaining without symptoms. A single mutation (G985) accounts for 95-98% of disease causing alleles (80% of affected individuals are homozygous for this mutation). Essentially, all cases have been of European ancestry.

INDICATIONS FOR TESTING:

• Confirmation of diagnosis in children/individuals presenting with acute life threatening events (including SIDS) and unexplained non-ketotic hypoglycemia.

• Prenatal diagnosis for carrier couples.

• Carrier screening in families of affected individuals.

SAMPLE REQUIREMENTS:

Blood: Two 5 ml purple top (EDTA) vacutainers of whole blood inverted several times to mix well. Forward within 48 hours at room temperature.

Amniotic fluid: 15-20 ml amniotic fluid from 14th-17th week of gestation. Send sample refrigerated but not frozen (do not ship on dry ice). Please use an overnight carrier service.

INTERPRETATION:

PCR based assays are used to detect the G985 mutation. Report will include assay results, background information and a calculation of residual carrier risk if results are negative.

COUNSELING ISSUES:

1. Identification of individuals with MCAD deficiency can lead to effective therapeutic modalities (frequent feedings, avoidance of prolonged fastings).

2. Early testing and diagnosis of infants in known carrier couples can lead to strategies to avoid morbidity.

< Back