Avital Adato, Michael D. Weston, Asher Berry, William J. Kimberling, Atsheva Bonne‐Tamir

The Usher syndromes are autosomal recessive hereditary disorders characterized by hearing impairment and progressive visual loss due to Retinitis Pigmentosa (RP). Moderate to severe sensorineural hearing loss and progressive RP characterizes Usher syndrome type IIa (USH2A), which maps to the long arm of chromosome 1q41. Recently, three deletions carried by USH2 patients, which were found in a novel gene isolated from the critical 1q41 region, defined this gene as responsible for USH2A. The USH2A gene is predicted to encode a 1546 amino acid protein which possesses domains that are observed in basal lamina and extracellular matrix proteins and in cell adhesion molecules. Affected individuals and additional members from eleven USH2 Israeli families of diverse ethnic origin were screened for the presence of changes in all 20 coding exons of the USH2A gene. Three novel mutations (239-242insCGTA, R334W, T1515M) were identified in three families of Jewish Moroccan and Jewish Iranian origins. Twelve polymorphisms were found in the families, four of which are novel. None of the known USH2 mutations were identified in the families studied in this work. Hum Mutat 15:388, 2000.