Association of Pro-inflammatory Cytokine Gene Polymorphism with Meniere's Disease in an Iranian Sample

Abstract

Meniere's disease (MD) is known as a rare chronic disorder of the inner ear with elevated serum levels of pro-inflammatory cytokines like tumor necrosis factor (TNF)-α, Interleukin (IL)-1, and IL-6. This study aims to evaluate genes polymorphism in some pro-inflammatory cytokines in a group of Iranian MD patients compared to the healthy controls. In this case-control study, 25 MD patients and 139 healthy controls were enrolled. DNA was extracted from blood samples, and single nucleotide polymorphisms were detected using polymerase chain reaction with sequence-specific primers assay. MD patients and controls were examined in terms of allele, genotype, and haplotype frequency of pro-inflammatory cytokine genes. Only the frequencies of alleles A/G at position -238 in the promoter of the TNF-α gene differed significantly between MD patients and healthy controls. G to A allele ratio was 23 and 3.6 in MD and controls, respectively. In individuals with MD, genotype GG was found to be significantly more prevalent at position -238 of the TNF-α gene promoter sequence. In addition, the heterozygote AG variant of -238 A/G TNF-α gene polymorphism was lower in MD patients than controls. Compared to the control group, the haplotype TNF- (-308, -238) AG was higher in MD patients, although not statistically significant. This is the first study that we know of that evaluates the frequencies of pro-inflammatory cytokine genes in an Iranian MD sample. This study shows the association between TNF-α and susceptibility to MD.

Keywords: Autoimmunity; Chemokines; Interleukins; Meniere disease; Polymorphism; Tumor necrosis factor-alpha.