Association of polymorphisms in GCKR and TRIB1 with nonalcoholic fatty liver disease and metabolic syndrome traits

In several genome-wide association studies, nonalcoholic fatty liver disease and alanine aminotransferase susceptibility variants have been identified in several genes, including LYPLAL1, ZP4, GCKR, HSD17B13, PALLD, PPP1R3B, FDFT1, TRIB1, COL13A1, CPNI, ERLIN1, CWF19L1, EFCAB4B, PZP, and NCAN. To investigate the relationship between these genes and nonalcoholic fatty liver disease in the Japanese population, we genotyped 540 patients and 1012 control subjects for 18 variations. We performed logistic regression analyses to characterize the association between the tested variations and nonalcoholic fatty liver disease. Metabolic syndrome and histological traits were also analyzed by linear regression. We also examined GCKR rs780094, TRIB1 rs2954021, and PNPLA3 rs738409 for epistatic effects. The A-allele of rs780094 in GCKR (P = 0.0024) and the A-allele of rs2954021 TRIB1 (P = 4.5x10(-5)) were significantly associated with nonalcoholic fatty liver disease. GCKR rs780094 was also associated with decreased plasma glucose, and increased triglycerides in the patient and control groups. GCKR rs780094 was also associated with an increased ratio of visceral to subcutaneous fat area in the patients with nonalcoholic fatty liver disease. Variations in GCKR, TRIB1, and PNPLA3 independently influenced nonalcoholic fatty liver disease and had no epistatic effects. Our data suggest variations in GCKR and TRIB1 are involved in the development of nonalcoholic fatty liver disease.