Reduction of Caloric Intake Might Override the Prosteatotic Effects of the PNPLA3 p.I148M and TM6SF2 p.E167K Variants in Patients with Fatty Liver: Ultrasound-Based Prospective Study

Background: The adiponutrin (PNPLA3) p.I148M and transmembrane 6 superfamily member 2 (TM6SF2) p.E167K variants represent risk factors for non-alcoholic fatty liver disease (NAFLD). In this study, we assessed the effects of caloric restriction on liver phenotypes in NAFLD patients in relation to the PNPLA3 and TM6SF2 genotypes. Methods: We genotyped both variants in 143 individuals with NAFLD (55 females, age 18-74 years) and 180 controls (85 females, age 33-66 years). Liver steatosis was assessed using the ultrasound-based Hamaguchi score. A 4-month dietetic intervention, consisting of restriction of daily caloric intake without changes in physical activity, was performed. Results: Both PNPLA3 (p = 0.002) and TM6SF2 (p = 0.041) variants were associated with NAFLD before intervention. Overall, 88 patients completed the intervention, which led to a significant decrease of steatosis, ALT activities, body mass index, hip and waist circumferences, and waist-hip ratio (all p < 0.0001). Hepatic steatosis and anthropometric traits improved significantly (p < 0.05) in carriers of either PNPLA3 or TM6SF2 risk genotype. The improvement of phenotypic traits, apart from WHR (p = 0.02), was not modified by the presence of PNPLA3 or TM6SF2 variants. Conclusions: The PNPLA3 and TM6SF2 polymorphisms are associated with NAFLD assessed by the Hamaguchi score. Neither PNPLA3 nor TM6SF2 risk alleles impair the response to dietetic intervention in NAFLD.