MTHFR and rheumatoid arthritis: We evaluated whether <i>HLA-DRB1</i>, <i>PNPLA3</i>, <i>SLCO1B1</i>, and <i>MTHFR</i> variants are associated with NAFLD, liver fibrosis, or MTX toxicity/pharmacokinetics in RA, after accounting for clinical covariates.