You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is In maple syrup disease, all of the following amino acids are excreted in urine, EXCEPT: and explain in detail?
The biochemical defect in maple syrup urine disease (branched-chain ketonuria, or MSUD) involves the alpha-keto acid decarboxylase complex. Plasma and urinary levels of leucine, isoleucine, valine, and their alpha-keto acids and alpha-hydroxy acids (reduced alpha-keto acids) are elevated, but the urinary keto acids derive principally from leucine. Signs and symptoms of MSUD include often fatal ketoacidosis, neurological derangements, mental retardation, and a maple syrup odor of urine. Ref: Rodwell V.W. (2011). Chapter 29. Catabolism of the Carbon Skeletons of Amino Acids. In D.A. Bender, K.M. Botham, P.A. Weil, P.J. Kennelly, R.K. Murray, V.W. Rodwell (Eds), Harper's Illustrated Biochemistry, 29e.