Isovaleric acidemia

Isovaleric acidemia is a rare inherited metabolic disorder in which the body cannot properly break down leucine, one of the branched-chain amino acids that come from dietary protein. It is a classical example of an organic acidemia and follows an autosomal recessive pattern, so a person is affected only after inheriting a faulty copy of the IVD gene from each parent. Without a working enzyme at the third step of leucine processing, isovaleric acid and related compounds build up to toxic levels and can damage the brain and nervous system. A well known sign is a distinctive odor of sweaty feet. In about half of cases symptoms begin within days of birth, with poor feeding, vomiting, seizures and lack of energy that can progress to coma, while in the others episodes come and go through childhood, often set off by infection. Newborn screening of urine or blood can detect it, and treatment centers on restricting dietary protein, especially leucine, with glycine or carnitine given during acute episodes.