PNPLA3 gene polymorphism accounts for fatty liver in community subjects without metabolic syndrome

Background: The rs738409 GG variant in patatin-like phospholipase 3 (PNPLA3) is associated with non-alcoholic fatty liver disease (NAFLD) and disease severity. However, it remains unclear if it contributes to the development of NAFLD through affecting dietary pattern.

Aim: To examine the association among PNPLA3 gene polymorphism, dietary pattern, metabolic factors and NAFLD.

Methods: Liver fat and fibrosis were assessed by proton-magnetic resonance spectroscopy and transient elastography in 920 subjects from a population screening project (251 had NAFLD). Dietary nutrient intake was recorded using a locally validated food-frequency questionnaire.

Results: The prevalence of GG genotype in NAFLD subjects was 20.7%, compared to 10.6% in controls (P < 0.001). Macronutrient intake was similar among subjects with different PNPLA3 genotypes. The presence of G allele was a predictor of NAFLD independent of nutrient intake and other metabolic factors (adjusted odds ratio to CC: CG, 2.00; GG, 2.68). In subjects without metabolic syndrome, G allele was even more closely correlated with NAFLD diagnosis (adjusted odds ratio to CC: CG, 2.22; GG, 3.39). The prevalence of NAFLD was only 12% in subjects with CC genotype and no metabolic syndrome, and increased to 34% in those with GG genotype and no metabolic syndrome. While NAFLD subjects had significantly lower fibre intake, there was no significant interaction between PNPLA3 and dietary pattern.

Conclusions: The G allele in PNPLA3 rs738409 increases the risk of NAFLD in the general population, especially in subjects without metabolic syndrome, independent of dietary pattern and metabolic factors.