Specific diagnostic marker for methylmalonic acidemia
A Biochemical Genetics Laboratory genetic counselor or consultant approval is required prior to specimen collection. The prenatal diagnosis is made on a dual, complementary approach involving direct chemical determination of methylmalonic acid (MMA) (at Mayo Medical Laboratories) in cell-free supernatant of amniotic fluid and molecular analysis for previously identified familial mutations or complementation studies (not currently offered at Mayo Medical Laboratories) in cultured amniocytes. Both tests are required for a definitive diagnosis. The amniocentesis must be performed between 16 and 19 weeks of gestational age. Previous knowledge of the complementation group (typically labeled as mut0, mut-, CblA, CblB, CblC, etc), associated homocystinuria, responsiveness to vitamin B12 of the affected child, and B12 intake of the mother during the pregnancy (if receiving treatment) are critical to secure an accurate prenatal diagnosis.
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
Methylmalonic Acid, AF
MMA, Amniotic Fluid