Natural History and Genetic Studies of Usher Syndrome

Background and objectives: The Usher syndromes are a group of clinically variable and genetically heterogeneous autosomal recessive syndromes. On the basis of clinical findings, at least three types exist. Patients with Usher type I are born deaf, have vestibular problems, and are thought to perceive night blindness in early childhood. Patients with Usher type II are born with a hearing deficit but are able to develop intelligible speech, do not have balance problems; night vision problems, and visual field changes are noted later. Patients with Usher type III are born with relatively good hearing that deteriorates over a decade or more; they can have progressive balance problems and they report night blindness in childhood or teens. Seven genes have been mapped so far for Usher type I while five of these genes have been identified. For Usher type II, four genes have been mapped and three of these have been identified while there is one cloned gene for Usher type III. Quite a lot of information is still unknown regarding the genetic nature of this syndrome. The picture of the three clinical types of Usher syndrome has also not been well studied up to this point and cross sectional studies seems to be the only source of the information available so far, regarding the natural history of the disease. The aim of this protocol is to better study the natural history of the disease and also make specific genotype-phenotype correlations. Study population: A total of 200 participants, including patients affected with all three clinical types of Usher syndrome and up to 200 unaffected relatives will be enrolled to the protocol. Unaffected family members, primarily parents and siblings will be enrolled to provide a blood sample when considered helpful for linkage analysis. Family members will be considered unaffected if they have had a previous normal examination and they don t have any symptoms of decreased night or peripheral vision. Methods: Participants will undergo ophthalmologic, audiologic and vestibular evaluation in order to be clinically characterized. Blood will be obtained by all participating subjects for the molecular studies. Patients who cannot come to NIH or a collaborating Institution for participation will be asked to provide a blood sample for genotyping and a copy of their ophthalmologic, audiology and vestibular records, to classify phenotype. Each off-site participant will be consented over the phone by an NEI investigator. All participants will be requested to fill out a questionnaire. Outcome measures: Affected participants will be phenotypically categorized in one of the three clinical types based on audiology and vestibular findings