Association between PPARGCIA polymorphisms and the occurrence of nonalcoholic fatty liver disease (NAFLD)

Background: Genetic factors as well as environmental factors are important in the development of NAFLD and in this study we investigated associations between polymorphisms of peroxisome proliferators-activated receptor gamma coactivator 1 alpha polymorphism (PPARGC1A) and NAFLD. Aims: We recruited 115 patients with biopsy-proven NAFLD, 65 with NASH and 50 with simple steatosis, and 441 healthy control subjects and investigated 15 SNPs of PPARGC1A. Results: SNP rs2290602 had the lowest p value in the dominant mode (p = 0.00095), and the odds ratio for NAFLD (95% CI) was 2.73 (1.48-5.06). rs2290602 was significantly associated with NAFLD even when the most conservative Bonferroni's correction was applied (p = 0.0143). The frequency of the T allele of rs2290602 was significantly higher in the NASH patients than in the control subjects (p = 0.00093, allele frequency mode), and its frequency in the NASH patients tended to be higher than in the simple steatosis patients (p = 0.09). The results of the real-time RT-PCR study showed that intrahepatic mRNA expression of PPARGC1A was lower in the TT group than in the GG or GT group at SNP rs2290602 (p = 0.0454). Conclusion: This is the first study to demonstrate a significant association between genetic variations in PPARGC1A and NAFLD. This finding suggested that PPARGC1A polymorphism and lower expression of PPARGC1A mRNA in the liver are an important genetic contribution to etiology of NAFLD.