Accordingly, these conflicting results of interaction may be explained by differences in target PADI4 SNP (padi4_89, padi4_90, padi4_92 vs padi4_94) or by differences in the major RA-susceptible SE alleles (for example, *0405 vs *0401) between Korean and Caucasian populations [41,42]. Here, PADI4 is linked to rheumatoid arthritis.