Methylmalonyl-CoA mutase activity of leukocytes in variants and heterozygotes of methylmalonic acidemia.

Abstract
An assay method for the methyl-malonyl-CoA mutase of human leukocytes obtained from 3 ml of blood was established. The enzyme activity which was measured with or without the in vitro addition of 5''-deoxyadenosylcobalamin was of value for the diagnosis of 2 variants of methylmalonic acidemia (vitamin B12 responsive and unresponsive), and also for the detection of heterozygotes with the vitamin B12 unresponsive type.