OBJECTIVETo provide prenatal diagnosis for deaf families, which the first child was confirmed to be hereditary deafness caused by gap junction beta-2 (GJB2) or SLC26A4 (PDS) mutation, to avoid another deaf birth in these families.

METHODSEight deaf families joined in this study. Each family had one child with severe to profound hearing loss while parents had normal hearing except a deaf father from family 8; mothers had been pregnant for 6-28 weeks. Genetic testing of GJB2, SLC26A4 and mitochondrial DNA (mtDNA) A1555G mutation were firstly performed in probands and their parents whose DNA was extracted from peripheral blood, and then prenatal testing was carried out in the fetus whose DNA was extracted from different fetus materials depending on the time of gestation.

RESULTSThe probands from family 1-4 were found to carry homozygous or compound GJB2 mutations while their parents carried corresponding heterozygous GJB2 mutations. The probands from family 5-8 and the deaf father from family 8 were found to carry compound SLC26A4 mutations while their parents and the mother from family 8 carried a single SLC26A4 mutation. Prenatal testing showed that the fetuses from family 1, 5, 8 only carried the paternal mutation and the fetuses from family 2, 3, 6 didn't carry any GJB2 or SLC26A4 mutations. The new born babies from these six families all had normal hearing revealed by new born hearing screening. However, the fetuses from family 4,7 carried the same mutations with probands in each family. The parents from family 4, 7 decide to terminate pregnancy.

CONCLUSIONPrenatal diagnosis assisted by genetic testing can provide efficient information about hearing condition of their offsprings.