Recent studies have shown higher frequencies of the CCR5-Δ32 allele and the CCR5-Δ32/Δ32 genotype, which confers protection against HIV infection, in northern Europe as compared to Mediterranean countries. Here, we analyse the prevalence of CCR5-Δ32 in 922 HIV seronegative blood donors in Israel to verify its frequency in Jews of Ashkenazi and Sephardi origin. A significant difference (P < 0.001) was found between the ccr5-δ32 allele frequency in ashkenazi (13.8%) vs (4.9%) jews. in contrast, no significant difference was observed in the frequency of the ccr2–64i mutation between ashkenazi (9.2%) and sephardi (13.4%) jews. using the island model we calculate that a minimal genetic migration rate of 3% per generation would have been necessary if the higher ccr5-δ32 prevalence in ashkenazi is to be fully explained by mixing with the indigenous north-european populations. this putative migration rate is 20-fold higher than that currently estimated from other genes, and would correspond to a non-realistic minimal current admixture of 80%. thus, our results suggest that a positive selection process for ccr5-δ32 should have occurred in northern europe at most a 1000 years ago, after the ashkenazi jews separated from their sephardi kin and moved to north europe.
This work was supported by the committee for the advancement of research and the Gonda-Goldschmied Medical Diagnostic Center at the Bar-Ilan University; and the National Institutes of Health under RO1 AI 43868 (LGK).