Methylmalonyl-CoA mutase deficiency

Methylmalonyl-CoA mutase deficiency is an inherited inborn error of metabolism in which the mitochondrial enzyme methylmalonyl-CoA mutase, which needs a vitamin B12 derivative to work, cannot convert methylmalonyl-CoA into succinyl-CoA. It is an autosomal recessive genetic disorder caused by defects in the MUT gene, and it accounts for about 60 percent of cases of methylmalonic acidemia. Newborns may show vomiting, acidosis, high ammonia, an enlarged liver, high glycine and low blood sugar, and thrombocytopenia and neutropenia can follow later. Patients with a complete gene lesion, called mut0, have the most severe symptoms, while those with a partial mutation, called mut-, show a wider range of severity.