Homocystinuria (cystathionine B-synthase deficiency)
Incidence
1:24,000-1:200,000 prevalence, autosomal recesive. More than 600 cases have been reported by 1985
Clinical Characteristics
Mental retardation from early life, ectopia lentis downward noted after age 2 years, thromboembolic episodes. Slender features, marfanoid features. Some mutations respond to pyridoxine (25 mg/kg/day). Psychiatric disturbances. Osteoporosis. Seizures in 20% of cases. High incidence of EEG abnormalities in pts. without seizures. Occasional dystonia.
Precipitants
None known. Elevated homocystine may precipitate crisis.
Provocation Tests
none
Diagnostic Procedures
EB-W/F cystathionine synthetase determination. Urine homocystine screen with nitropruside test.