RESUMEN
Context: Sudden deafness (SSHL) belongs to the category of diseases causing neurological hearing loss with a sudden and unknown etiology. The pathogenesis and mechanism of SSHL aren't clear at present. Gene polymorphisms may be associated with increased or reduced risk of hearing impairment. Objective: The study intended to investigate the association between susceptibility to SSHL and single nucleotide polymorphisms (SNPs) at the rs2228612 locus of the DNA methyltransferase (DNMT1) gene and at the rs5570459 locus of the gap junction protein Beta 2 (GJB2) gene, to provide a basis for the prevention and treatment of the SSHL. Design: The research team performed a case-control study. Setting: The study took place at Tangshan Gongren Hospital in Tangshan, China. Participants: Participants were 200 SSHL patients admitted to the hospital between January 2020 and June 2022, the study group, and 200 people with normal hearing, the control group. Outcome Measures: The research team: (1) performed the Hardy-Weinberg Balance Test to determine the frequency distribution of the data for the rs2228612 locus of the DNMT1 gene and for the RS5570459 locus of the GJB2 gene for the groups, (2) analyzed the relationships between the genotypes and SSHL susceptibility, (3) determined the relationship between gene frequencies and gender and the SSHL susceptibility of males and females with different genotypes, (4) determined the relationship between gene frequencies and smoking and the SSHL susceptibility of smokers and nonsmokers with different genotypes, and (5) determined the relationship between gene frequencies and drinking alcohol and the SSHL susceptibility of drinkers and nondrinkers with different genotypes. Results: The numbers of participants in the study group with the CC genotype and the C allele at the rs2228612 locus of the DNMT1 gene were significantly lower than the numbers in the control group (P < .05). The CC and C alleles were significant protective factors against SSHL (P < .05).The numbers of participants in the study group with the GG genotype and the G allele at the rs5570459 locus of the GJB2 gene were significantly higher than the numbers in the control group (P < .05), and the GG genotype and the G allele significantly increased SSHL susceptibility (P < .05). The TC+CC genotype at the rs2228612 locus of the DNMT1 gene was a protective factor against SSHL in male and smoking participants (P < .05). The AG+GG genotype at the rs5570459 locus of the GJB2 gene increased the susceptibility of females, smokers, and drinkers to SSHL (P < .05). Conclusions: The TC+CC genotypes at the rs2228612 locus of the DNMT1 gene were significant protective factors against SSHL. The SSHL susceptibility was higher in participants carrying the AG+GG genotype at the rs5570459 locus of the GJB2 gene. In addition, gender and drinking can affect SSHL susceptibility.