Seven novel mutations in mut methylmalonic aciduria

Methylmalonic aciduria (MMA) is an autosomal recessive inborn error of metabolism that results from functional defects in methylmalonyl CoA mutase (MCM), a nuclear-encoded, mitochondrial enzyme that uses the vitamin B₁₂ derivative, adenosylcobalamin (AdoCbl) as a cofactor. To date, 23 mutations have been identified at the MUT locus on the short arm of chromosome 6, causing the mut forms of MMA (mut complementation group; mut MMA, McKusick #251000). We now report seven novel mutations. Three were found in mut⁰ patients: R228Q (c759G→A) was found as a heterozygous change; G312V (c1011G→T) and 346delL (c1112delCTT) were both found as homozygous changes. Four mutations were found in mut^– patients: A191E (c648C→A) and V633G (c1974T→G) were found in the same patient; 684insL (c2128insCTC) and L685R (c2130T→G) were both found as homozygous changes. The recent modelling of the human methylmalonyl CoA mutase allowed for an interpretation of the identified mutations. Hum Mutat 11:270–274, 1998. © 1998 Wiley-Liss, Inc.