Determination of factor V Leiden mutation and R2 polymorphism in cis position.

FVA4070G (R2 polymorphism) influences plasma factor V (FV) concentration and was associated with mild activated protein C resistance. This polymorphism was reported to have a trans inheritance with FV Leiden (FVL) mutation. The aim of this study is to investigate the inheritance of R2 polymorphism in the homozygous FVL carriers. In this study, 99 patients with thrombosis and 7 individuals without a history of thrombosis all of which homozygous for FVL were included. Of 99 patients, 1 was heterozygous for FV A4070G. Additionally, 6 polymorphisms in the FV gene were analyzed for the heterozygous R2 patient and her family. When the allelic distribution was classified, 8 different haplotypes were obtained. In contrast to the literature, it was shown that R2 polymorphism could be inherited in cis position with FVL and also the family members could have co-inheritance of the FVL and R2 on the same chromosome as proband.