Reply: Factor V Kuwait alias Factor V R3: A Rare Polymorphism of Uncertain Functional Significance

We would like to thank Castoldi et al. for their valuable comments on our previously published article describing a novel mutation in the clotting factor V gene found in 2 Arab patients with venous thrombosis who were living in Kuwait [factor V Kuwait (FVK) mutation or FV H1254R polymorphism]. As stated by Castoldi et al., the FVK mutation is a very rare one. We have to state here that this polymorphism had not been registered in the human gene bank before we found it in our patients, giving us the impression that it had not been described before. We were the first to register it in the human gene bank with the accession number AY881018. In addition, the FVK mutation was not described as a part of the HR2 haplotype, the haplotype we were originally studying when we found the FVK mutation. In fact, both our patients who had the FVK did not have the HR2 haplotype.