International Journal of Biomedicine (Dec 2020)
The structure of Haplotypes and Diplotypes in the PNPLA3 gene in the Yakut Population
Abstract
Background: The first GWAS searching for such genetic factors identified the PNPLA3 gene as a major genetic determinant for the predisposition to nonalcoholic fatty liver disease in Hispanic, African American, and European American populations, according to liver fat contents, a finding that was subsequently confirmed by liver biopsy in Europeans and Asians. The aim of our research was to study the distribution of alleles, genotypes, haplotypes and diplotypes of polymorphic variants of the PNPLA3 gene (rs2294918 and rs738409) in Yakuts. Methods and Results: The PNPLA3 SNPs (rs2294918 and rs738409) were analyzed by PCR-RFLP reaction. The PNPLA3 rs738409 SNP in the Yakut population is characterized by a high frequency of the risk G allele (72%). According to the PNPLA3 rs2294918 SNP, which suppresses the negative effect of rs738409, the protective PNPLA3 (rs2294918) A allele was found only in 10.7% of study subjects. Analysis of the distribution of the frequency of genotypes in the studied sample of Yakuts showed the predominance of the carriage of the PNPLA3 rs738409 GG genotype (57.3%) and the PNPLA3 rs2294918 GG genotype (80.7%). The frequency of the PNPLA3 (rs2294918) AA and AG genotypes was 2.0% and 17.3%, respectively. The Yakuts often have two diplotypes [GG]-[GG] and [CG]-[GG]. Both diplotypes carry the PNPLA3 rs738409 G allele (45.3% and 28%) and do not carry the PNPLA3 rs2294918 A allele. The high frequency of the [GG]-[GG] and [CG]-[GG] diplotypes in Yakuts (45.3% and 25%, respectively), carrying mutant alleles G (rs738409) and not carrying the A allele (rs2294918), indicates that these diplotypes were probably adaptively favorable to the Yakuts. Conclusion: The analysis of haplotypes and diplotypes based on the markers rs738409 and rs2294918 of the PNPLA3 gene may contribute to future new biomarkers for the diagnosis of nonalcoholic fatty liver disease and nonalcoholic steatohepatitis, as well as provide fundamental knowledge on human adaptation to cold.
