What is Maple syrup urine disease?

Maple syrup urine disease: A hereditary disease that is due to deficiency of an enzyme involved in amino acid metabolism, characterized by urine that smells like maple syrup. In maple syrup urine disease, the three branched-chain rel=dict amino acids (leucine, rel=dict isoleucine, and rel=dict valine) cannot be metabolized (processed), and they build up in the blood, causing problems with brain function and leading to mental retardation, physical disability, and death, if not treated. Treatment involves use of a special diet and monitoring of protein intake.

A genetic condition in which the body can't process certain protein building blocks. It causes sweet-smelling pee.