... consists of a special diet, continued indefinitely.Homocystinuria (<1 in 100,000). Lack of an enzyme that converts the amino acid homo-cysteine into cystathionine, needed for normal brain development. ... several other enzymes, leading to buildup of lactic acid and other organic acids. Untreated, can cause brain damage, coma, and death. Symptoms, including skin rashes and hair loss, usually begin ... resulting in illness in first week of life. Severity varies, but death dur-ing first month and lifelong brain damage are common. Treatment includes low-protein diet, vitamin B12 injections, and...