[Genetic testing and mutation analysis for the cochlear implantation children and their normal auditory phenotype...

To investigate the characteristics and significant of mutations of GJB2 gene, SLC26A4 gene and mitochondrial 12S rRNA in deaf children who received cochlear implantation (CI) in Yunnan and to provide the data for diagnoses and research of recovery in C1 children.

Genomic DNA was extracted from the peripheral blood samples collected from 46 children and their parents (110 cases). All the children received the CI. Their parents had normal auditory phenotype. PCR was performed and the products were sequenced by automated DNA sequencer to detect the hot spots of mutations.

The detection rates of GJB2 235delC (13.0%) and 109G>A (24.0%) mutations were significantly higher than other mutations. SLC26A was the secondary major mutation (13.0%). We found out that no patient carried the mitochondrial 12S rRNA mutations. Leukoencephalopathy, hyperbilirubinemia and hypoxic-ischemic injure were disclosed in 7 patients (15.2%). The rate of mutations in parents was 36.0% (23/64). There had no difference between Han and other racial minorities (P>0.05).

The CI recipients in Yunnan with a high frequency of 235 delC and 109 G>A mutation, IVS7-2A>G (6.5%) is also a common mutation related hearing loss; aminoglycoside antibiotics may not be the main reason which induced congenital deaf in CI children; environment facts was suggested to contribute another important cause. The hot-spots gene screening for the C1 children could offer an accurate genetic counseling for early diagnosis and treatment, it also provide evidences for the clinical analysis between mutations and curative effect.