REL and rheumatoid arthritis: Among the genetic factors, human leukocyte antigen (HLA) loci (HLA-DRB1) and non-HLA genes (PTPN22, PADI4, TRAF1/C5, TNFAIP3, CCR6, REL, etc.)are the main susceptibility risk factors for RA across multiple ethnic groups (Barton et al., 2008; Raychaudhuri et al., 2012; Kochi et al., 2014; Mcgonagle et al., 2018; Shaik and Banaganapalli, 2019).