Peroxisome proliferators-activated receptor γ2 Pro12Ala variant is associated with body mass index in non-alcoholic fatty liver disease patients

Abstract

Background: Non-alcoholic fatty liver disease (NAFLD) is a major cause of chronic liver disease globally and commonly associated with insulin resistance and metabolic syndrome (MS). Peroxisome proliferator-activated receptor-γ (PPARγ) is a transcription factor abundantly expressed in adipocytes and plays a key role in the regulation of adipocyte differentiation, lipid and glucose homeostasis. Pro12Ala variant has been earlier associated with obesity, type 2 diabetes and MS. Aim: The present study aimed to determine the genotype frequencies of the Pro12Ala variant in NAFLD patients and any further association with other phenotype in the patients. Patients and methods: Ninety-eight NAFLD patients and 280 matched controls were genotyped for presence of the Pro12Ala variant. Genomic DNA was extracted and polymerase chain reaction-restriction fragment length polymorphism using Bst-UI was performed for the detection of C-G change at codon 12 position of PPAR γ2 gene. Genotype and allele frequencies were compared between patients and controls. The Hardy-Weinberg equilibrium was tested by comparing expected/observed genotype frequencies by χ² test. Results: The frequencies of Pro/Ala genotype were comparable between NAFLD patients and controls. In the controls, 213 (75.7%) were homozygous for the wild-type (Pro/Pro) genotype and 67 (23.9%) were heterozygous (Pro/Ala). In NAFLD patients, genotypic distribution of wild type, heterozygous and homozygous were 63 (64.3%), 34 (34.7%) and 1 (1%), respectively. Heterozygous genotype was found to be significantly higher in the patients (P = 0.01). We also analyzed related phenotypic association of the patients with Pro12Ala genotype. We observed that the Pro12Ala (heterozygous) genotype was significantly higher in the patients who had body mass index >25 kg/m² (P = 0.025). Conclusions: Pro12Ala variation of the PPAR γ2 gene is associated with NAFLD and might play a role in the pathogenesis of NAFLD.