描述
Maple Syrup Urine Disease (Branched-chain alpha-keto acid dehydrogenase deficiency, MSUD) is caused by a deficiency of the branched-chain alpha-keto acid dehydrogenase enzyme complex (BCKDH), which normally degrades the branched chain amino acids leucine, isoleucine, and valine. The disease is characterized in an infant by the presence of sweet-smelling urine, with an odor similar to that of maple syrup. Increased amounts of valine, leucine and isoleucine and their toxic byproducts accumulate in the blood, plasma, and urine. Symptoms include ataxia, encephalopathy, ketosis, mental retardation, seizures, and a maple syrup or caramel odor.