DNA methylation in hearing-related genes in non-syndromic sensorineural hearing loss patients

Abstract

Abstract Background Our understanding of epigenetic modifications in the inner ear is very limited. Although epigenetic regulation of genes related to individual organ- and system-limited pathologies are generally expected to be tissue-specific, DNA methylation patterns in peripheral blood (PB) are found to be associated with the presence of several diseases with no typical hematological involvement. Here, we aimed to investigate whether there is a correlation between hearing-related genes’ promoter region methylation in the PB samples with the presence of non-syndromic sensorineural hearing loss (NSSHL) with an aim of future utilization of DNA methylation as biomarkers in hearing loss. The study included 26 patients with NSSHL and a control group of 20 healthy individuals. CpG islands in the promoter regions of the GJB-2, GJB-6, and SLC24A genes were analyzed using bisulfite sequencing, and methylation percentages were analyzed. Results Methylation levels at the 1st region of GJB-6 and the 1st and the 4th regions of SLC26A4 were found to differ significantly (p = 0.039, p = 0.042, and p = 0.029, respectively) between the patients and the control group. There was no statistically significant difference in methylation percentages of GJB-2 promoters. We also found that parents’ consanguinity determines the methylation levels in patients’ families. Conclusions According to our knowledge, this is the first study that investigates epigenetic changes in the PB of patients with NSSHL. Despite the small sample size, our findings indicate that DNA methylation patterns in the PB could be of use for understanding epigenetic changes in the inner ear and the clinical management of NSSHL.