Study on VNTR polymorphism of gene IL-1RA in 19 Chinese populations.

Earlier studies suggested that a variable number tandem repeat (VNTR) polymorphism in intron 2 of the interleukin-1 receptor antagonist (IL-1RA) gene might be associated with some chronic inflammatory diseases, autoimmune diseases and solid tumours. To study the distribution of this polymorphism in China, 1352 samples were collected from 19 widely distributed Chinese populations. PCR was used to genotype the VNTR. The overall frequencies of allele 1 and allele 2 were 0.913 and 0.064 respectively. The frequency of the allele 2 was significantly different between the northeastern and the northwestern populations. Moreover, the allele frequencies at this locus in three Chinese Han populations were different from that in minority populations. When compared with other populations worldwide, the frequencies of the two alleles in China were not significantly different from those in the Asian and Pacific Islands. However, the prevalence of allele 1 in China was significantly higher, and the prevalence of allele 2 was significantly lower, than those in American and European Caucasians, and the pairwise Fst values reinforced this observation. The differences of the allele frequencies between different regions and within the same region showed that geography and race have important roles in the population differentiation for the IL-1RA gene. In summary, our results provide a valuable reference for population genetic information and future disease association studies in Chinese populations.