OBJECTIVETo assess the impact of natural selection and genetic background on the polymorphisms of HLA-G 3-untranslated regions (UTR) among five ethnic Chinese populations.

METHODSPCR and DNA sequencing were used to determine the polymorphisms among 432 individuals from the five ethnic populations. Their genetic background was determined by genotyping of 10 short tandem repeats (STRs).

RESULTSEight variations were identified among Gelao, Mongolian and Kirgiz populations, while only 7 were found in Shui and Dai people. For all 3 southern populations (Gelao, Shui, and Dai), the observed heterozygosites (Ho) was higher than expected heterozygosities (He). But this was reversed for the 2 northern populations (Mongolian and Kirgiz). The Ho and He of the 10 neutral STRs were in random distribution. Ewens-Watterson testing based on haplotypes of the HLA-G 3'UTR has suggested that a natural selection had occurred in the region where Dai and Shui had inhabited, but not in the northern region where Mongolian and Kirgiz population inhabited. Polygenetic trees based on the HLA and STRs were also different.

CONCLUSIONThe HLA-G 3'UTR of Dai and Shui people who lived in southern China may have subjected to a selection pressure. Based on current knowledge, this pressure may have been driven by a pathogenic selection.