The frequency of 844ins68 mutation in the cystathionine beta-synthase geneis not increased in patients with venous thrombosis

Background and Objectives. A frequent mutation in the cystathionine beta-sy nthase (CBS) gene (844ins68, a 68-bp insertion in the coding region of exon 8) was recently discovered. In the present study we Investigated this muta tion as a candidate risk factor for venous thrombosis. Design and Methods. The prevalence of the 844ins68 CBS mutation was determi ned in 101 patients with objectively diagnosed deep venous thrombosis and i n 101 healthy controls matched for age, sex and race. PCR amplification of a DNA fragment containing exon 8 of the CBS gene was employed to determine the genotypes, Additionally, Bsrl restriction enzyme digestion of the PCR p roducts was performed in all samples from carriers of the insertion, to tes t for concurrent presence of a second mutation (T833C) in the CBS gene. Results. The insertion was found in 21 out of 101 patients (20.8%; allele f requency 0.109) and in 20 out of 101 controls (19.8%; allele frequency 0.11 4), yielding a relative risk for venous thrombosis related to the 844ins68 CBS mutation close to 1.0. In addition, the T833C GBS mutation was detected in all alleles carrying the 844ins68 CBS insertion, confirming the co-inhe ritance of the two mutations. Interpretation and Conclusions. Our findings do not support the hypothesis that the 844ins68 mutation in the CBS gene is a genetic risk factor for ven ous thrombosis. (C)1998, Ferrata Storti Foundation.