OBJECTIVETo analyze the molecular pathogenesis of deaf couples by means of genetic testing. To provide accurate genetic counseling and instruction for deaf couples with different etiology based upon results of genetic testing.

METHODSFour deaf families from July 2005 to May 2006. Each subject was with moderate to profound hearing loss. Genomic and mitochondrial DNA (mtDNA) of each subject were extracted from whole blood. Genetic testing of GJB2, SLC26A4 (PDS) and mtDNA A1555G mutation were offered to each individuals.

RESULTSThe husband from family 1 didn't carry GJB2, SLC26A4 and mtDNA A1555G mutation while his wife was confirmed to carry compound SLC26A4 mutations. The possibility of their offspring's to be SLC26A4 single mutation carrier was 100%. The couple from family 2 both didn't carry GJB2, SLC26A4 and mtDNA A1555G mutation. The possibility of their offspring's having hereditary deafness caused by GJB2, SLC26A4 and mtDNA A1555G mutation was excluded. The husband from family 3 was confirmed to carry homozygous GJB2 mutations and a single SLC26A4 mutation while his wife who was diagnosed with enlarged vestibular aqueduct syndrome (EVAS) by CT scan was proven to carry a single SLC26A4 mutation. The risk of their offspring's suffering EVAS was 50%. The husband from family 4 was mtDNA A1555G positive while his wife who was diagnosed with cochlear malformation by CT scan didn't carry GJB2, SLC26A4 and mtDNA A1555G mutation. The risk of their offspring's having hereditary deafness caused by GJB2, SLC26A4 and mtDNA A1555G mutation was excluded.

CONCLUSIONSGenetic testing could be applied to offer the more accurate genetic counseling and instruction to deaf couples.