Coexistence of IL-6 -572C/G and ICAM-1 K469E Polymorphisms among Patients with Sudden Sensorineural Hearing Loss.

Sudden sensorineural hearing loss (SSNHL) is a multifactorial disease, and its etiology remains elusive. SSNHL is possibly caused by both the environmental factors and genetic alterations. Recently, several studies suggested that inflammation may be involved in the pathogenesis of SSNHL, and certain gene polymorphisms may have correlations with SSNHL. Interleukin 6 (IL-6) functions both as a pro-inflammatory cytokine and an anti-inflammatory factor. Intercellular adhesion molecule-1 (ICAM-1) is a member of the immunoglobulin family that is also involved in inflammation response. Importantly, the IL-6 gene promoter contains a single nucleotide polymorphism (SNP), -572C/G, and ICAM-1 gene contains a SNP (A/G) in the protein-coding region, Lys (AAG)/Glu (GAG) at codon 469, known as K469E polymorphism. However, there is no study about the ICAM-1 gene polymorphism among SSNHL patients. In this study, we explored the relationship between SSNHL with IL-6 -572C/G and ICAM-1 K469E polymorphisms. We conducted a case-control study including 75 SSNHL patients and 165 healthy controls and analyzed the distribution and odds ratios of IL-6 and ICAM-1 genotypes. The frequency of the G allele at IL-6 -572C/G polymorphism was significantly higher among SSNHL patients than that among healthy individuals. In multivariate analysis, the coexistence of IL-6 -572G allele (GG/CG) and E allele (EE/KE) of ICAM-1 K469E polymorphism was significantly associated with an increased SSNHL risk (P < 0.001). In conclusion, we propose that the combination of IL-6 -572C/G and ICAM-1 K469E polymorphisms have a synergistic effect on the onset of SSNHL.