Background: Cytokines are polypeptides that play critical roles in immune responses. Gene
polymorphisms occurring in the inflammatory cytokines are taking a role in autoimmune diseases,
including multiple sclerosis (MS), which may induce inappropriate immune responses.
Objective: The aim of this study was to investigate the allelic and genotypic frequencies of interferon
gamma gene (IFN-γ) at +874A/T locus and tumor necrosis factor (TNF-α) at+308A/G locus in MS
patients of Azeri population.
Methods: At first, a questionnaire was prepared for each of 240 healthy, non-relative, and 152 Azeri
MS patients before obtaining the blood sample from all subjects. After DNA extraction, the frequency
of alleles and genotypes of the IFN-γ and TNF-α genes at +874A/T and -308G/A loci, respectively,
were determined by allele-specific PCR method. Finally, the frequencies were compared between control
and MS patients by chi-square test (x2-test) and p<0.05 was considered significant.
Results: In the IFN-γ +874A/T gene single nucleotide polymorphism (SNP), the most allelic and genotypic
frequencies in MS patients were the A allele, 55.26% (p=0.04) and the AT genotype, 52.63%
(p=0.048). In healthy individuals, it was 65.42% for the A allele and 45.42% for the AA genotype. For
the TNF-α 308 G/A SNP, the highest allelic and genotypic frequencies in MS patients were the G allele
with 55.92% (p<0.001) and AG genotype with 61.84%, and in healthy subjects, the allelic and
genotypic frequencies were 84.2% and 70.8% for the G allele and GG genotype, respectively.
Conclusion: Head trauma, the infection with the herpes virus and Mycoplasma pneumonia, frequent
colds and high consumption of canned foods provide grounds for MS. The T allele in the IFN-γ gene
(+874) and the genotypes of AA and AG at the TNF-α gene (-308) at the position-308 were considered
as potential risk factors for MS. Therefore, the polymorphisms in cytokine genes and following
changes in their expression levels can be effective in susceptibility to MS.