Interestingly, this SNP is absent in East Asian (e.g., Japanese) populations, that instead present common genetic variants of PADI4, a gene encoding peptidyl-arginine deiminase (PAD, a peptide citrullination enzyme), that are associated with increased risk of RA (OR 1.31/allele copy) (38, 40, 41). Here, PADI4 is linked to rheumatoid arthritis.