Results of Hearing Test Combined with Gene Test for Deafness in Patients with Hearing Impairment：an Analysis of 5 664 Cases from Shandong Province

BackgroundAs a common disease causing human health impairment and disability, deafness has a leading morbidity among all the disabling diseases. Many factors could lead to deafness, among which genetic factors account for about 60%. Gene screening and pedigree analysis can be used to determine whether one has hereditary deafness, so as to provide corresponding genetic counseling services for hereditary deafness patients to stop the transmission of deafness from one generation to the next.ObjectiveTo investigate the hearing loss status and prevalence of mutations in genes associated with deafness in deafness patients from Shandong, to identify pathogenic causes of hearing impairment.MethodsOur study included a total of 5 664 hearing-impaired patients with a hearing disability certificate or a diagnosis of hearing loss, who participated in the genetic testing program for hereditary hearing loss in Shandong Province from 2016 to 2020. Hearing loss was tested by pure-tone audiometry. Genetic testing was carried out with DNA microarray to detect mutations at 15 loci in four common hereditary deafness-related genes.ResultsAmong the 5 664 cases, 3 891 had grade 1 (mild) hearing disability, 1 463 had grade 2 (moderate) hearing disability, 188 had grade 3 (severe) hearing disability, 73 had grade 4 (profound) hearing disability, and the remaining 49 consisting of 38 cases of microtia and 11 cases of external auditory canal closure. In terms of deafness-related gene mutations, 2 503 cases were detected with mutations, 1 227 of them (21.66%) carrying GJB2 gene mutations, 975 (17.21%) carrying SLC26A4 gene mutations, 97 (1.71%) carrying mitochondrial 12S rRNA gene mutations, 158 (2.79%) carrying GJB3 gene mutations, and 46 (0.81%) carrying double heterozygous mutations. Both GJB2 and SLC26A4 gene mutations were hotspot mutations in patients with grades 1-4 hearing disability. The prevalence of mutations in GJB2 and SLC26A4 genes was higher in those with grade 1 hearing disability than in those with grade 2 hearing disability (P