Furthermore, the distribution of haplotypes and genotype combination in our cohort indicated increased RA risk in individuals carrying the rs17860508/rs3212227 2/A haplotype or 2.2/AC+CC combination, while 1/A haplotype or 1.1/AA combination may be protective for RA.
The pooled results demonstrated that IL-12B rs3212227 (homozygote model: OR = 0.96, 95 % CI = 0.81-1.15; heterozygote model: OR = 1.07, 95 % CI = 0.93-1.23; dominant model: OR = 1.05, 95 % CI = 0.91-1.20; recessive model: OR = 0.93, 95 % CI = 0.79-1.10) and rs6887695 (homozygote model: OR = 1.01, 95 % CI = 0.84-1.21; heterozygote model: OR = 1.14, 95 % CI = 0.86-1.51; dominant model: OR = 1.14, 95 % CI = 0.87-1.48; recessive model: OR = 1.01, 95 % CI = 0.85-1.21) polymorphisms may not be associated with RA risk.
Frequencies of the rs3212227 CC genotype were statistically higher in patients with RA compared with the healthy control group in both codominant and recessive models (P = 0.037; P = 0.04, respectively).
The present study suggests that the IL12B +1188A/C (rs3212227) polymorphism might be associated with genetic susceptibility to autoimmune diseases, such as T1D, RA, BD, but not GD and AS.
These findings suggested that the functional single nucleotide polymorphism (SNP) IL-12A rs2243115 GG genotype may increase the risk of RA in RF negative patients, and the IL-12B rs3212227 AC and AC+CC genotypes are associated with RA risk in older patients, RF positive patients and ACPA negative patients.