Comparative frequency of Coagulation Factor II and Coagulation Factor V Alleles among new-born and senior citizens

Abstract

Resistance to activated protein C is one of the most common inherited disorders associated with hereditary thrombophilia. A missense mutation in the gene coding for coagulation factor V (CF V Leiden) and which renders this procoagulant factor resistant to inactivation by activated protein C results in an inherited risk for venous thrombosis. Recently, another mutation has been identified in the prothrombin gene (CF II G20210A) which was also associated with increased risk for venous thrombosis. In this study, we sought to establish the frequency of the two alleles in a random sample of Maltese newborn and compare these with the frequencies of the same alleles among senior citizens and patients with clinical thrombophilia. The control population of 554 newborn samples processed for the same point mutations gave 13 (2.3%) who were CF V Leiden heterozygotes and 7 (2.7%) who were CF II G20210A heterozygotes. Neither homozygotes nor trans-heterozygotes (i.e. CF V Leden and CF II2 0210A heterozygotes) were observed. The 348 senior citizens gave 9 (2.6%) CF V Leiden heterozygotes and 8 (2.4%) CF II G20210A heterozygotes. Neither homozygotes nor trans-heterozygotes (i.e. CF V Leden and CF II20210A heterozygotes) were observed. The 328 patients referred to the Laboratory of Molecular Genetics, University of Malta, with clinical thrombosis gave 23 (7.01%) CF V Leiden heterozygotes and 24 (7.31%) CF II G20210A heterozygous. One patient was found to be trans-heterozygous for the two mutations. The data suggested that although CF V G1691A and CF II G20210A may increase risk for thrombophilia, they do not impact on the survival of the carriers, but the transheterozygozity may also confer increased risk. The high allele frequency may be best explained by positive natural selection.