Background: Malonyl coenzyme A (CoA) decarboxylase (MCD) deficiency is a rare AR organic acidemia, caused by mutations in gene MLYCD, in which malonyl-CoA is not decarboxylated to acetyl-CoA due to deficiency of the malonyl-CoA decarboxylase enzyme (23). This evidence concerns the gene MLYCD and inborn organic aciduria.