<prompt> Deficiency of enzyme αketo acid decarboxylase leading to a block in the metabolism of branch chain amino acids is observed inMaple syrup urine diseaseHartnups diseaseAlkaptonuriaPhenylketonuria  <response>: Maple Syrup urine disease It is an inherited autosomal recessive disorder of branched-chain amino acid i.e. - Mine, Leucine and Isoleucine.Maple syrup urine disease MSUD is dt defect in enzyme - α-keto acid dehydrogenase.It is a mitochondrial, enzyme complex consisting ofα-ketoacid decarboxylaseDihydrolipoyl dehydrogenase and Transacylase The early steps in the metabolism of these three amino-acids are similar. One of the steps - decarboxylation is accomplished by a complex enzyme system i.e. branched chain α-keto acid dehydrogenase using thiamine pyrophosphate vitamin B1 as a coenzyme. Deficiency of this enzyme system causes the disease, named after the sweet odour of maple syrup found in the body fluids - urine, sweat etc.Clinical featuresAffected infants are initially normal at birth but develop poor feeding and vomiting during the Pt week of life; lethargy and coma may ensue within a few days.Physical examination reveals hypertonicity and muscular rigidity with opisthotonos spasm in which the body forms a bow like a figurePeriods of hypertonicity may alternate with bouts of flaccidity.Convulsion occurs in most infants, and hypoglycemia is common However in contrast to most hypoglycemic states, correction of the blood glucose level does not improve the clinical condition. 