Maple Syrup Urine Disease

Maple syrup urine disease is a rare inherited metabolic disorder caused by deficiency of an enzyme complex needed to break down three branched-chain amino acids, leucine, isoleucine and valine, which then build up to toxic levels in the blood. The disease takes its name from the distinctive sweet, maple-syrup-like odor it gives to the urine and earwax of affected infants, who without treatment can develop poor feeding, lethargy, seizures and death within the first weeks of life. It is managed with a strict lifelong diet that limits the three amino acids, and the disorder was first described in the medical literature in 1954.