A Pilot Study Assessing the Possible Combined Effect of Physical Activity and PNPLA3 rs738409 Polymorphism on the Risk for Non-Alcoholic Fatty Liver Disease in the Japanese Elderly General Population

Purpose: The patatin-like phospholipase domain containing protein 3 (PNPLA3) rs738409 polymorphism (c.444C>G) is the most well-known genetic risk factor for non-alcoholic fatty liver disease (NAFLD), but whether or not physical activity influences the association between the PNPLA3 genotype and risk of NAFLD is unclear. Patients and Methods: A retrospective longitudinal analysis was conducted among 352 Japanese subjects. Each type of physical activity was assigned a metabolic equivalent (MET), and the subjects were classified into sedentary, low or high groups using the "METS*T" (METs x hours per week) value of 5 or 21 as a threshold. Results: Among the PNPLA3 G/G genotype carriers, the high and low METS*T groups had a lower risk of NAFLD than the sedentary METS*T group (odds ratio [95% confidence interval]: 0.14 [0.02-0.99] and 0.16 [0.03-1.04], respectively). Furthermore, the PNPLA3 C/C or C/G genotype carriers showed no significant difference in the risk of NAFLD among the three METS*T groups. Conclusion: The PNPLA3 rs738409 genotype may be associated with the beneficial effects of physical activity on the risk of NAFLD among elderly Japanese individuals. Further comprehensive investigations are therefore needed to verify the preliminary results.