CLINICAL TRIALS AND OBSERVATIONS Brief report Prothrombin 20210GA is an ancestral prothrombotic mutation that occurred in whites approximately 24 000 years ago

den are common prothrombotic muta-tions in whites for which founder effects have been established. In this study, we analyzed the frequencies of 5 single nucle-otide polymorphisms (SNPs) and 9 micro-satellites flanking the prothrombin gene (F2) in 88 homozygotes for 20210A and 66 homozygotes for 20210G. For estimating the age of the prothrombin 20210G>A mutation, we used the DMLE2.0 pro-gram, which analyzed linkage disequilib-ria between the mutation and the multiple markers that had been assessed. This analysis yielded an age estimate of 23 720 years (95 % credible set, 19 080-31 340 years). A similar analysis by the DMLE2.0 program was performed on 5 SNPs from previously studied homozy-gotes for factor V Leiden and controls that yielded an age estimate of 21 340 years (95 % credible set, 16 880-29 480 years). The occurrence of the 2 mutations in whites toward the end of the last glacia-tion and their presently wide distribution in whites suggest selective evolutionary advantages for which some evidence was reported (diminished blood loss) or is controversial (protection against infec-tions). (Blood. 2006;107:4666-4668) © 2006 by The American Society of Hematolog