Factor V Leiden and Thrombophilia

Abstract

Greengard et al. (Dec. 8 issue)¹ describe siblings, from a symptomatic family, who were homozygous for the arginine → glutamine mutation at position 506 in the factor V gene. On the basis of this report and others,^2-4 one can estimate that there are hundreds of thousands of homozygotes in Europe and the United States. Many of them probably come from families in which the heterozygous state is asymptomatic, since the mutation is very common in the general population.^1-4 At present, it is not known whether homozygous members of such families have an increased risk of thrombosis.