Homocystinuria due to cystathionine beta–synthase deficiency
Analysis ID 189
Analysis location “GENESIS” Centre for Medical Genetics
Diagnosed illness Homocystinuria due to cystathionine beta–synthase deficiency
OMIM 236200
Clinical information Classic homocystinuria is an autosomal recessive metabolic disorder of sulphur metabolism. The clinical features of untreated homocystinuria due to CBS deficiency are usually manifested in the first or second decade of life and include myopia, ectopia lentis, mental retardation, skeletal anomalies resembling Marfan syndrome, and thromboembolic events. Biochemical features include increased urinary homocystine and methionine excretion. There are two major phenotypes of the disorder: a milder pyridoxine (vitamin B6)-responsive form, and a more severe pyridoxine-nonresponsive form. Pyridoxine is a cofactor for the CBS enzyme involved in the conversion of homocysteine to cysteine. Some patients have been reported to present with a milder form of homocystinuria, which was characterized by an elevated plasma homocysteine level and increased risk for thrombotic incidents, but with no skeletal, ocular, or nervous system manifestations associated with the classical form.
Type of analysis Molecular
Type of biological material 5 ml of peripheral blood collected in an ETDA tube; DNA sample
Analyzed genes CBS
Analysis description Sequencing of exon 8 of the CBS gene
Analysis indication Symptoms of homocystinuria
Analysis time 3 - 4 weeks
Refund Yes
CGM laboratory name Laboratory for Molecular Genetics