At multivariate analysis adjusted for sex, age and steatosis ≥ 2 the association between the PNPLA3 I148M variant and lower serum niacin remained strongly significant in NAFLD individuals who belonged to the Validation cohort with BMI ≥ 30 kg/m2 (β = –0.24, 95% CI: –0.43–0.06, p = 0.009, Table 2), thus corroborating the hypothesis that the PNPLA3 p.I148M missense variation may be a genetic modifier of vitamin B3 metabolism. This evidence concerns the gene PNPLA3 and steatosis.