Table 1.

Main molecular variation underlying the RA risk variability.

Items	Relationship with RA	Ref.
class II HLA genes	Increases the risk of RA by enhancing the ability of cell antigen presentation, such as HLA-DRB1 haplotypes	(20–22)
the 620W allele at PTPN22	Some regional differences have been observed; increases the risk of RA by regulating B and T cell-mediated autoimmune responses	(15, 23)
CCR6	Acts as a potential pathogenic gene	(15, 24, 25)
STAT4	Acts as a potential pathogenic gene	(15, 25)
PADI4	Related to the citrullination of arginine residues in RA	(26, 27)
CTLA4	Acts as a potential pathogenic gene; encodes for the cytotoxic T-cell associated protein	(25, 28)
CD40	The SNP in CD40 affects the immune system in RA by regulating the expression of CD40	(29, 30)
rs7607479	Protects RA joints with positive autoantibodies by regulating the expression of SPAG16 and MMP in RA synovium and FLS	(32)
rs2900180	Possibly related to bone and joint erosion in RA	(33)
rs2833522	Contains H3K4me3 histone markers, transcription factors, and long non-coding RNA, which are related to the degree of bone destruction in ACPA-negative RA patients	(34)
rs6427528	Associated with changes in disease activity score after treatment with the anti-TNF-α drug (etanercept) by regulating CD84	(35)
rs7195994	Associated with the response to anti-TNF-α therapy (infliximab)	(36)