OBJECTIVEAnalyzed the molecular pathogenesis of probands by means of genetic test and assisted the local Family Planning Institute by providing prenatal genetic counseling and instruction for deaf families who eager to have more baby.

METHODSTotal of forty-three deaf families were recruited by two institutes for family planning from Guangzhou and Weifang. Forty-two families had one deaf child with normal hearing parents. One family was that parents and their child were all deaf. Genetic testing of GJB2, SLC26A4 and mitochondrial DNA (mtDNA) 12SrRNA were firstly performed in probands and their parents, following medical history, physical examination, auditory test and CT scan of temporal bone were completed. And then the genetic information and instruction were provided to each deaf family.

RESULTSFifteen of these 43 families had positive results of genetic test. In fifteen families, one family was confirmed that the parents and their child all carried homozygous GJB2 mutations and the recurrence risk was 100%. Twelve families were confirmed that the probands carried homozygous/compound GJB2 or SLC26A4 mutations while their parents were GJB2 or SLC26A4 carriers, and the recurrence risk was 25%. One family was confirmed that the proband, diagnosed with enlarged vestibular aqueduct syndrome (EVAS) by CT scan, carried heterozygous SLC26A4 mutation from the mother, and the recurrence risk was still 25% based on the hereditary pattern of EVAS although another SLC26A4 mutation from the father was not found. One family was confirmed that the proband carried a heterozygous GJB2 mutation from the mother and the possibility to be GJB2 carrier for offsprings was 50%. The rest 28 families were that all probands and their parents did not carry GJB2, SLC26A4 and mtDNA 12SrRNA pathological mutation.

CONCLUSIONSGenetic testing can provide more accurate and useful prenatal genetic counseling and instruction to deaf families. Meanwhile, it is an ideal way to develop a cooperative relationship with the institute for family planning.