SMN1 and rheumatoid arthritis: AIH: autoimmune hepatitis; ANA: anti-nuclear antibodies; anti-SMA: anti-smooth muscle antibodies; anti-SLA/LP: anti-soluble liver antigen/liver-pancreas; anti-LKM-1: anti-liver kidney mitochondrial-1; SLE: systemic lupus erythrematousus; anti-Sm: anti-Smith; RA: rheumatoid arthritis; RF: rheumatoid factor; anti-CCP: anti-cyclic citrullinated peptide; NSAIDs: non-steroidal anti-inflammatory drugs; NAFLD: non-alcoholic fatty liver disease; PSC: primary sclerosing cholangitis; P-ANCA: perinuclear anti-neutrophil cytoplasmic antibodies