Homocystinuria due to Cystathionine Beta-Synthase Deficiency

Homocystinuria due to cystathionine ß-synthase (CBS) deficiency is the most common inborn error of methionine metabolism, characterized by involvement of the eye (ectopia lentis and/or severe myopia), skeletal system (marfanoid habitus, osteoporosis, scoliosis, pectus excavatum, genu valgum), vascular system (premature atherosclerosis and thromboembolism), and central nervous system (developmental delay/mental retardation, seizures, psychiatric problems). Any or [...]

Homocystinuria due to cystathionine ß-synthase (CBS) deficiency is the most common inborn error of methionine metabolism, characterized by involvement of the eye (ectopia lentis and/or severe myopia), skeletal system (marfanoid habitus, osteoporosis, scoliosis, pectus excavatum, genu valgum), vascular system (premature atherosclerosis and thromboembolism), and central nervous system (developmental delay/mental retardation, seizures, psychiatric problems). Any or all of these systems may be involved. There is variable expressivity even among patients within the same family. Ectopia lentis may be the only presenting feature in some patients, other individuals can present with a thromboembolic event as an adult. About half of all CBS deficient patients respond to pharmacologic doses of pyridoxine (vitamin B6). Pyridoxine-responsiveness is constant within sibships. It has been estimated that newborn screening for elevated methionine levels detects only about one-third of patients.