[Genotypic analysis of familial dilated vestibular aqueduct syndrome]

To analyze clinical manifestation of patients from two families with dilated vestibular aqueduct syndrome (DVAS). Their genotypic patterns were discriminated with the genetic testing methods for PDS gene.

The twin sisters from pedigree and the brother and sister from pedigree 2 all suffered from sensorineural hearing loss. All patients from these two families were confirmed to have enlarged vestibular aqueduct by temporal bone CT scan. Exon 7+8 and their flanking area sequences were analyzed by direct sequencing. All other exons and their flanking sequences were screened by DHPLC. The amplicons of exons which showed abnormal DHPLC wave pattern were further sequenced.

The parents of two families are non-consanguineous, hearing normal couples with no other family members with hearing loss. Both families have two offspring with DVAS. The clinical features of all patients were progressive hearing loss, good communication ability but with thickness pronunciation. Both twin sisters from pedigree are homozygous for the splice site mutation (IVS 7-2 A-G) affecting the 3 splice site consensus sequence of intron 7. The brother and sister of pedigree 2 are compound heterozygotes for 1199 ins T mutation and a missense mutation (1229 C-T).

Familial DVLS is typical hereditary disease. The patients with DVLS have similar clinical manifestation and the same genotypic changes in PDS.