TM6SF2 rs58542926 is not associated with steatosis and fibrosis in largecohort of patients with genotype 1 chronic hepatitis C

Background & Aims: We tested the putative association of the rs58542926 variant of TM6SF2, a recently described genetic determinant of nonalcoholic fatty liver disease, with steatosis and fibrosis in genotype 1(G1) chronic hepatitis C(CHC) patients. Methods: A total of 694 consecutively biopsied Caucasian G1 CHC patients were genotyped for TM6SF2 rs58542926, IL28B rs12979860 and PNPLA3 rs738409. Steatosis was classified as absent (<5%), mild-moderate(5-29%) and severe(≥30%), Fibrosis was considered severe if=F3-F4. Results: Carriers of TM6SF2 rs58542926 (6.3% of patients) exhibited lower serum levels of cholesterol (P=0.04) and triglycerides (P=0.01), but a similar distribution of steatosis severity (P=0.63), compared to noncarriers. Prevalence and severity of steatosis were reduced in IL28B C allele carriers (P=0.005) and elevated in PNPLA3G allele carriers (P<0.001). After adjustment for age, gender, body mass index and homoeostasis model assessment score, steatosis severity was independently associated with IL28B rs12979860 (odds ratio [OR] 0.69, 95% confidence interval [CI] 0.55-0.86, P=0.001) and PNPLA3 rs738409 (OR 1.84, 95% CI 1.46-2.83, P<0.001), but not TM6SF2 rs58542926 (OR 1.48, 95% CI 0.82-2.69, P=0.19). Variants of TM6SF2 (30.9% vs. 25%, P=0.40), IL28B and PNPLA3 were not directly associated with fibrosis severity, although variants of IL28B and PNPLA3 promoted steatosis (OR 1.36, 95% CI 1.06-1.75, P=0.01) that in turn is associated with severe fibrosis. Conclusions: In G1 CHC patients, TM6SF2 rs58542926 does not affect the histological severity of liver damage. However, IL28B rs12979860 and PNPLA3 rs738409 modify steatosis.