Distribution of the alcohol dehydrogenase ADH1B*47His allele in Eurasia.

To the Editor: Recently, Li et al. reported on the frequency of the derived allele ADH1B*47His in Eastern and Western Asia. The data were based on meta-analysis of the published results for 131 populations and the results of genotyping of samples from 37 additional populations, performed by the authors. The authors made the suggestion that there had been separate and independent increases in the frequency of the ADH1B*47His allele in Eastern and Western Asia. Their worldwide-frequency-distribution diagram for this allele also includes the previous reports that there is a regional elevation in the ADH1B*47His allele for Eastern Europeans (Russians). The authors acknowledged that Central Asian population data that would support their conclusion about this distribution are, as yet, absent. The allele-frequency data derived from the two previous studies were essential for the hypothesis that a local maxima for distribution of ADH1B*47His might exist on the Russian Plain and in Southwest Asia. We noted, however, that the frequencies of the ADH1B*47His allele presented in these studies for Russians and Iranian populations are significantly distinct from the allele frequency for the same or neighboring population groups reported in other studies. There are several fairly obvious factors that could produce these differences: first, genotyping errors might occur, depending on methods that vary between the different studies; second, small (nonrepresentative) numbers of genotyped samples were included; third, genetic drift might occur in a local community enrolled in genotyping within the ethnic group of interest; fourth, there might have been recent undetected gene flow from a distant geographic region with a different frequency of the allele. There are reasonable concerns that errors in genotype data for some populations might affect the meta-analysis and the resulting conclusions regarding the evolution of this functionally significant polymorphism. In this Letter, we elucidated the allele-frequency data for Russians and Southwest Asian populations and added data on Central Asian and Siberian populations to provide a complete description of the Eurasian distribution of the ADH1B*47His allele. We have typed the ADH1B Arg47His polymorphism for 3408 individuals in 46 additional populations by PCR-RFLP withMslI using primers and protocols described eslewhere and have developed a refined geographic map that includes 172 populations from Africa and Eurasia (Figure 1, Table 1).