Homocystinuria

**Definition:** Autosomal recessive inborn error of methionine metabolism usually caused by a deficiency of CYSTATHIONINE BETA-SYNTHASE and associated with elevations of homocysteine in plasma and urine. Clinical features include a tall slender habitus, SCOLIOSIS, arachnodactyly, MUSCLE WEAKNESS, genu varus, thin blond hair, malar flush, lens dislocations, an increased incidence of MENTAL RETARDATION, and a tendency to develop fibrosis of arteries, frequently complicated by CEREBROVASCULAR ACCIDENTS and MYOCARDIAL INFARCTION. (From Adams et al., Principles of Neurology, 6th ed, p979)

**Tree numbers:** - C10.228.140.163.100.365 - C16.320.565.100.480.500 - C16.320.565.189.365 - C17.300.428 - C18.452.132.100.365 - C18.452.648.100.480.500 - C18.452.648.189.365