Genetic Counseling And Prenatal Diagnosis For Hearing Loss Based On Genetic Testing

With the project of human genome being completed, there has been remarkable progress being made on hereditary hearing loss. Since the majority of Chinese hereditary deaf people have been confirmed to be caused by GJB2 gene, SLC26A4gene and mtDNA mutations, genetic testing of these three genes can assist us with making clear about cause of deafness and providing theoretical evidences for genetic counseling which make genetic information and instruction more scientific and accurate. Furthermore, it makes prenatal diagnosis possible for deaf families. By means of genetic testing, we systematically carried out the clinical practices of genetic counseling and prenatal diagnosis for Chinese deaf people and families; meanwhile, we took the preliminary survey on recurrence risk of deaf families and the attitude of deaf youth and parents from deaf families towards genetic testing.Part one: Genetic counseling for deafness based on genetic testing.Genetic testing has promoted the development of genetic counseling undoubtly. By means of genetic testing, we carried out the clinical practices of genetic counseling for 217 deaf youths, 4 deaf couples and 30 deaf families that the parents hoped to have a normal hearing baby. We provided more accurate genetic information and instruction for these counseling subjects based on results of genetic testing and then set up the procedure and strategy of genetic counseling for deafness. Besides, we took a survey on recurrence risk of 605 deaf families and reached to preliminary statistical results which showed that the recurrencerisk of deaf families is very high; meanwhile we also investigated 124 deaf young adults and 107 parents from deaf families about the attitude towards genetic testing and the results demonstrated most of them have the positive attitude. Results from the two surveys will be helpful for genetic counseling.Part two: Prenatal diagnosis for hereditary deaf families assisted by genetic testingBy means of genetic testing, we analyzed the molecular pathogenesis of 16 deaf families expecting to have a normal hearing baby whose first children are all deaf, confirmed that probands were caused by GJB2 or SLC26A4 mutations and then provided prenatal diagnosis for these families. Among the 16 deaf families, 12 fetuses were confirmed to only carry a single or no GJB2 or SLC26A4 mutations. 6 of the 12 fetuses have been given the birth and all had normal hearing revealed by new born hearing screening. The other 6 fetuses' mothers are still in pregnant. The rest 4 fetuses carried the same mutations with probands and their parents decided to terminate pregnancy. Prenatal diagnosis assisted by genetic testing can provide efficient information about hearing condition of their offsprings and avoid another deaf birth.