Letter to the Editor: Factor V Kuwait alias Factor V R3: A Rare Polymorphism of Uncertain Functional Significance

We have read with great interest the recent article by Jadaon et al. [1] reporting a novel coagulation factor V (FV) gene polymorphism (FV Kuwait) in the Arab population of Kuwait. While genotyping a group of thrombotic patients for the well-known FV R2 polymorphism (A4070G, H1299R [2]) by Rsa I restriction analysis of exon 13, the authors observed an unexpected restriction pattern suggesting the existence of a different polymorphic Rsa I restriction site in the same amplicon. Direct sequencing of the PCR product revealed an A]G transition at position 3935, which predicts the replacement of His 1254 by an Arg in the B domain of the protein. This polymorphism was detected in 2 out of 188 patients with venous thrombosis, but it was absent in 100 healthy controls, raising the possibility that it might contribute to the risk of venous thrombosis in the Arab population.