An analysis of a large postlingually deaf family with hereditary non-syndromic profound hearing loss

We initiated a clinical and genetic linkage study on members of a large Ven ezuelan family with hereditary hearing loss. medical history and a physical examination were performed on 30 family members. Audiometry was carried ou t in 25 subjects, and in 2 additional children auditory brainstem responses were obtained. Additional testing (site-of-lesion, electronystagmography a nd computed tomography) was also obtained in a few subjects. DNA was extrac ted from blood samples from 25 family members. The type of deafness in this family is neurosensorial. non-syndromic and postlingual. The average age o f onset of deafness is 7 years and there is a rapid progression leading to profound deafness. Deafness is possibly of cochlear origin and there is no associated vestibular pathology. Analysis of the pedigree discloses a mater nal pattern of inheritance with a significant female predominance, compatib le with a mutation of the mitochondrial DNA. The molecular DNA analysis for the known mitochondrial mutations are discussed.