Association of Interleukin-12B Gene Polymorphism With Multiple Sclerosis in Patients From Southeast of Iran

Background: The presence of polymorphisms in IL-12B gene, encoding IL-12 P40 subunit, is associated with a number of autoimmune diseases. Objectives: The current study aimed at evaluating the association of a single nucleotide polymorphism (SNP; rs3212227) in IL-12B gene with multiple sclerosis (MS) in patients from Southeast of Iran. Methods: Blood specimens were collected from 140 patients with MS as the caseand 140 gender-andage-matched healthy subjects as the control groups. The genomic DNA was extracted and the genetic variations in SNP rs3212227 were determined using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. Results: The frequencies of AA, AC, and CC genotypes in SNP rs3212227 were 55.0%, 17.9%, and 27.1% in patients with MS, and 61.4%, 29.3%, and 9.3%, in healthy subjects, respectively. The frequency of CC genotype at rs3212227 was significantly higher in patients with MS as compared with the healthy controls (P < 0.001). However, the AC genotype was less prevalent in patients with MS than the healthy control ones (P < 0.02). The frequency of A and C alleles at SNP rs3212227 were 63.09% and 36.07% in patients with MS and 76.07% and 23.9% in healthy control subjects, respectively. The frequency of C allele was significantly higher, whereas the frequency of A allele was lower in patients with MS than the healthy control subjects (P < 0.001). The frequency of CC genotype in SNP rs3212227 was significantly higher in patients with relapsing remitting MS (RRMS), secondary progressive MS (SPMS), and primary progressive MS (PPMS) patterns in comparison with the healthy control subjects (P < 0.002, P < 0.001 and P < 0.05, respectively). In patients with RRMS pattern, the frequency of AC genotype (18.6%) was significantly lower than that of the control group (29.3%, P < 0.05). In patients with RRMS and SPMS patterns the frequency of C allele was significantly higher in comparison with that of the control group (P < 0.03 and P < 0.001, respectively). Conclusions: The results represented that the presence of CC genotype and C allele in SNP rs3212227 of IL-12B gene were associated with susceptibility to MS disease, whereas the presence of AC genotype and A allele may confer protection against the disease.