On the basis of the levels of diversity observed in the CD209/CD209L genomic region, we calculated the average number of pairwise differences (π) and the Watterson's estimator (θw) (Watterson 1975). Under the standard neutral model of a randomly mating population of constant size, these are unbiased estimators of the population mutation rate θ=4Neμ, where N e is the diploid effective population size and μ is the mutation rate per generation per site. To test whether the frequency spectrum of mutations conformed to the expectations of this standard neutral model, we calculated Tajima's D (Tajima 1989) and Fay and Wu's H tests (Fay and Wu 2000). P values for the different tests were estimated from 104 coalescent simulations under an infinite-site model, with use of a fixed number of segregating sites and the assumption of no recombination, which has been shown to be a conservative assumption (Gilad et al. 2002). In parallel, we estimated P values for all these tests, using the empirical distribution obtained from sequencing data of 132 genes in a panel of 24 African Americans and 23 European Americans (Akey et al. 2004). All these analyses, together with the interspecies McDonald-Kreitman (McDonald and Kreitman 1991) and K A/K S (Kimura 1968) tests, were performed using the DnaSP package (Rozas et al. 2003). Genetic distances between populations (F ST) and heterozygosity values were estimated using the Arlequin package (Schneider et al. 2000). F ST statistical significance was assessed using 10,000 bootstrap replications. To bear out a deficit or an excess of heterozygosity in the neck region of CD209 and CD209L, we used BOTTLENECK (Cornuet and Luikart 1996) to compute for each geographic region, the distribution of the heterozygosity expected from the observed number of alleles, given the sample size (n) under the assumption of mutational-drift equilibrium. This distribution was obtained through simulation of the coalescent process of n genes under two mutational models, the infinite-site model and the stepwise mutation model. In addition, to obtain information on the fraction of genetic variance in the neck region that is due to intra- and interpopulation differences, we performed an analysis of molecular variance (AMOVA), using the Arlequin package (Schneider et al. 2000). The AMOVA results were compared with those of 377 microsatellites analyzed in the same population panel (Rosenberg et al. 2002).