<prompt> Branched chain ketoaciduria is a defect of catabolism of all the following aminoacids except-LeucineIsoleucineValineMethionine  <response>: Ans. is d i.e., Methionine Branched chain ketoaciduria or Maple Syrup Urine Disease MSUD is caused by a defect of branched chain keto acid dehydrogenase enzyme complex BCKD. BCKD catalyses the second step of catabolism of branched chain amino acids - Leucine, Isoleucine and Valine. 