PADI4 and rheumatoid arthritis: [41] Since then, several reports using Caucasian samples showed negative association between RA susceptibility and PADI4 polymorphisms, while the association was repeatedly confirmed in Asian populations.[42]–[47] Currently, based on amassing of research evidence, PADI4 is considered as RA susceptibility gene even in Caucasian populations though its impact on disease susceptibility is lower than in Asian populations. [16].