[Common deafness gene mutations of non-syndromic hearing loss in Liaoning]

Investigate common deafness gene mutations in patients with severe and profound non-syndromic hearing loss in Liaoning in order to understand their hereditary etiologies and characteristics at the molecular level.

Peripheral blood samples were obtained and the DNA templates were extracted from 128 non-syndromic hearing loss patients who are sporadic in clinics. The deafness gene chip was applied to detect hot-spot deafness gene mutations including GJB2, GJB3, SLC26A4 and mitochondrial 12S rRNA. Deafness etiology questionnaires, pure tone audiometry, auditory brainstem response, tympanometry and temporal bone CT were also applied.

Various types of gene locus mutations were seen in 52 of the 128 patients (40.6%); (1) GJB2 gene mutations (n=22) included c. 235 del C homozygous mutation (n=10), c. 235 del C heterozygous mutation (n=5); c. 176_191 del 16 heterozygous mutation (n=l); c 35 del G heterozygous mutation (n=l); c. 235 del C/c. 299_300 del AT mutation (n=l), c. 235 del C/c. 176_191 del 16 mutation (n=l), c. 35 del G/c. 176_191 del 16 mutation (n=l); c. 299_300 del AT/c. 919-2 A>G mutation (n=l), c. 235 del C/c. 919-2 A>G mutation (n=l). (2) SLC26A4 gene mutations (n=30) included c. 919-2 A>G homozygous mutation (n=6), c. 919-2 A>G heterozygous mutation (n=17), c. 2168 A>G homozygous mutation (n=l), c. 2168 A>G heterozygous mutation (n=2), c. 2168 A>G/c. 919-2 A>G mutation (n=2), c. 919-2 A>G/GJB2 c. 235 del C mutation (n=2); (3) No GJB3 and mitochondrial 12S rRNA mutation. Genetic deafness was confirmed at the gene level in 24 cases (18.8%) and 28 patients (21.9%) were diagnosed as carriers of genetic deafness gene mutations.

Genetic deafness occupies a large population in deaf community in Liaoning. Molecular genetic screening for these mutations and genetic counseling are effective methods to prevent the occurrence of hereditary hearing loss and provide theoretical guidance.