NCF1 and rheumatoid arthritis: Among others, missense variants in the NCF1 gene have been associated with systemic lupus erythematosus (SLE), Sjögren’s syndrome, and rheumatoid arthritis (RA) [34]; two missense polymorphisms in NCF2 were described as predisposing to SLE [35]; and common polymorphisms in NCF4 were associated both with RA and Crohn’s disease [36,37].