Mutations in 66 genes are known for autosomal recessive, in 36 genes for autosomal
dominant and in 5 genes with x-linked non-syndromic types of hearing loss. Furthermore,
there are known digenic mechanisms in hereditery hearing loss.
284 patients were selected for a retrospective analysis and we performed genetic diagnostics
by panel diagnostic.
In more than 80% of the patients genetic mutations in hearing loss genes were detected,
in 54% the diagnosis was secure or most likely to cause hereditary hearing loss. The
most frequent genes were GJB2 (17%), MYO7A (8%), MYO15A (7%), TECTA (6%) and MYO6
(3%). The autosomal recessive forms of GJB2 (DFNB1A) and MYO7A (DFNB2) were associated
with pre-lingual deafness. Patients with mutations in MYO15A (DFNB3) showed a variable
beginning and progressive character of hearing loss. The clinical progress of the
autosomal dominant forms in MYO7A (DFNA11), TECTA (DFNA8/DFNA12) and MYO6 (DFNA22)
showed a later on-set of hearing impairment and manifestation of the deafness. CI-patients
with GJB2-mutation showed the best hearing results (80% at 65dB). The speech perception
of patients with mutations in MYO15A, TECTA und MYO6 was 70%, in patients with MYO7A-mutations
40%. Patients with mutated CACNAD1, MYO7A, LOXHD1, PTPRQ, CDH23, TFAP2A, COL9A3, TMPRSS3,
GPR98 and TJP2 showed speech perception scores below 50%.
High throughput sequencing allows to diagnose known deafness genes. Genotype-phenotype-correlation
allows predictions regarding the clinical course of hearing impairment. The treatment
with a CI shows a good outcome for the most common genes GJB2, MYO15A, TECTA and MYO6.
