BCKDHB and maple syrup urine disease: Maple syrup urine disease (MSUD) is an autosomal recessive disorder of branched chain amino acid (leucine, valine, isoleucine) catabolism due to branched-chain alpha-ketoacid dehydrogenase complex (BCKD) deficiency encoded by BCKDHA, BCKDHB, and DBT genes [7,8].