PADI4 and rheumatoid arthritis: Two different meta‐analyses showed that PADI4 polymorphisms, such as PADI4_89, PADI4_90, PADI4_92, PADI4_94 and PADI4_104, were associated with rheumatoid arthritis in the Asian population.10, 21 Single nucleotide polymorphisms (SNPs) are the most common type of genetic variation, and some of them are thought to be functional.