Population genetic diversity in relation to microsatellite heterogeneity

Nine populations (Germans, Turks, Moroccans, Ovambos, Ugandans, Chinese, Japanese, Papuans, and Australian Aborigines) were investigated using six microsatellite systems (HumCD4, Hum F13B, HumFES/FPS, HumTH01, HumVWA, and D21S11), so-called STRs (short tandem repeats). Allele frequency data and sequencing results were used to compare the population genetic diversity among these populations. The genetic differences varied depending on the STR applied. According to the systems investigated, we defined three categories of STR microvariation: LOMs (low microvariation systems), INMs (intermediate microvariation systems), and HIMs (high microvariation systems). LOMs (STRs: CD4, FES, F13B, TH01) are characterised by a number of repeats between 5-15 and a stable repeat sequence. INMs and HIMs each showed an increasing number of repeats and additional sequence variation in the repeat motifs. The rate of new mutations was associated with the extent of microvariation. The reconstruction of phylogenetic trees led to a clustering in an early split of the African populations followed by further branching of the Asian/Melanesian and the Caucasian groups.