<prompt> Enzyme deficient in maple syrup urine disease?a-ketoacid decarboxylaseTransaminaseIsomeraseMutase  <response>: Maple syrup urine disease is due to deficiency of a-ketoacid dehydrogenase also called a-ketoacid decarboxylase. In maple syrup urine disease there is excretion of branched chain amino acids isoleucine, leucine, valine and their keto acids a-keto b-methylvalerate, a-ketoisocaproate, a-ketoisovalerate in urine. 