methylmalonic aciduria

Excretion of excessive amounts of methylmalonic acid in urine owing to deficient activity of methylmalonyl-CoA mutase or deficient cobalamin reductase. Two types occur: 1) an inborn error of metabolism resulting in severe ketoacidosis shortly after birth, with long-chain urinary ketones; autosomal recessive inheritance, caused by mutations in the methylmalonyl-CoA mutase gene (MCM) on chromosome 6p [MIM*251000]; 2) acquired, a type due to vitamin B₁₂ deficiency [MIM*251110] due to defective synthesis of adenosylcobalamin.

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methylmalonic aciduria n a metabolic defect which is controlled by an autosomal recessive gene and in which methylmalonic acid is not converted to succinic acid with chronic metabolic acidosis resulting