INTRA-POPULATION AND INTER-POPULATION DIVERSITY AT SHORT TANDEM REPEAT LOCI IN DIVERSE POPULATIONS OF THE WORLD

To study the level of intra- and inter-population variation at hyperva riable DNA loci, we have characterized 15 human populations of diverse ethnic and geographic origins at six short tandem repeat loci by usin g the polymerase chain reaction. Even though the spectrum of allelic v ariation is quite broad and there are substantial differences in allel e frequency distributions among populations, in general, populations w ithin a major racial group show a greater degree of similarity. This o bservation is reflected in the analysis of gene diversity. When the to tal diversity is apportioned, the maximum variation becomes attributab le to inter-individual differences within a population; of the variati on that is attributable to differences between populations within a ra cial group and differences between racial groups, the former is smalle r than the latter. Separate analysis of gene diversity for each of the major population groups based on geographic and ethnic relationship s hows that the total gene diversity is higher for the larger racial gro ups, namely, African, Caucasian and Mongoloid, than the American India ns and the Pacific Islanders. As expected, a reciprocal relationship b etween gene diversity and F-ST levels is observed. Higher values of F- ST in the American Indian and the Pacific Islanders may reflect smalle r population size and a higher level of isolation. An analysis of gene tic distance encompassing the populations belonging to the three major racial groups recognizes three distinct clusters - all the population s of African affiliation cluster together, as do the Caucasian affilia ted and the Mongoloid groups, in two distinct clusters. Interestingly, three broadly classified cosmopolitan US populations, namely, US Whit e, US Black and US Asian, cluster with their ancestrally related popul ations. This study dispels some of the concerns regarding the applicab ility of DNA typing data for forensic use.