Methylmalonic academia (MMA) is a rare form of organic acidemias characterised by an inborn error of methylmalonate and cobalamin metabolism. The most of MMA cases are caused by mutations in the methylmalonyl-CoA mutase (MUT) gene. The MUT gene encodes the enzyme MUT that converts l-methylmalonyl-CoA to succinyl-CoA. Partial or complete enzyme deficiency occurs because of the mutations in the MUT gene. As a result, methylmalonyl acid and other potentially toxic compounds accumulate in the tissues, leading to signs and symptoms of MMA. Here, we report a novel p.V438Sfs*3 (c.1311_1312InsA) mutation in MUT gene in a newborn with severe MMA.