Maple syrup urine disease

Maple syrup urine disease (MSUD) is a rare inherited metabolic disorder caused by deficient activity of the branched-chain alpha-ketoacid dehydrogenase complex. It affects the metabolism of leucine, isoleucine, and valine. When these amino acids are not properly broken down, they accumulate in urine and become toxic. The disease is named for the distinctive sweet odor of affected infants' urine and earwax.

Disease type

Rare, inherited metabolic disorder

Affected amino acids

Leucine, isoleucine, and valine

Name origin

Sweet odor of infants' urine and earwax