Isolated methylmalonic acidemia (MMA) is a rare group of inborn errors of metabolism caused either by a deficiency of the enzyme methylmalonyl‐CoA mutase (MMUT), defects in the transport or metabolism of its cofactor, adenosylcobalamin, or deficiency of the enzyme methylmalonyl‐CoA epimerase [1]. This evidence concerns the gene MMUT and methylmalonic acidemia.