The MC4R SNPs, their haplotypes and gene-environment interactions on the risk of obesity

BACKGROUND: Little is known about the correlation between the melanocortin 4 receptor gene (MC4R) single nucleotide polymorphisms (SNPs) and the risk of obesity. This research sought to test the MC4R rs17782313, rs476828 and rs12970134 SNPs, their haplotypes and gene-environment interactions on the risk of obesity in the Maonan ethnic group, an isolated minority in China. METHODS: A case-control study comprised of 1836 participants (obesity group, 858; and control group, 978) was conducted. Genotypes of the three SNPs were determined by the next-generation sequencing (NGS) technology. RESULTS: The genotypic frequencies of the three SNPs were different between the obesity and control groups (P < 0.05 for all). The minor allelic frequency of the MC4R rs17782313C, rs476828C and rs12970134A was higher in obesity than in control groups (13.8% vs. 8.3%, P < 0.001, 17.1% vs. 10.9%, P < 0.001; and 15.5% vs. 11.5%, P < 0.001; respectively). Additionally, the dominant model of rs17782313 and rs476828 SNPs revealed an increased morbidity function on the risk of obesity (P < 0.05). A correlation between SNP-environment and the risk of obesity was also observed. The rs17782313C-rs476828C-rs12970134A haplotype was associated with high risk of obesity (OR = 1.796, 95% CI = 1.447–2.229), whereas the rs17782313T-rs476828T-rs12970134G and rs17782313T-rs476828T-rs12970134A haplotypes were associated with low risk of obesity (OR = 0.699, 95% CI = 0.586–0.834 and OR = 0.620, 95% CI = 0.416–0.925; respectively). The interactions between haplotype and waist circumference on the risk of obesity were also noted. CONCLUSIONS: We discovered that the MC4R rs17782313, rs476828 and rs12970134 SNPs and their haplotypes were associated with the risk of obesity in the Chinese Maonan population.