[Genetics of Usher syndrome].

Since the first gene (MYO7A) for Usher syndrome was identified 14 years ago, there has been substantial progress in the elucidation of the genetic basis of this disorder, revealing extensive genetic heterogeneity (with nine genes known to date). Most Usher genes have similar functions, localize to similar regions in inner ear hair cells and retinal photoreceptors, and interact with each other. Approximately 80% of the patients carry mutations in one of the known Usher genes. One major challenge for the scientific community is to identify the remaining causative genes. Moreover, it is still largely unclear which genetic factors are responsible for the clinical variability that can be observed even between affected siblings. The establishment of high-throughput techniques shall soon provide comprehensive genetic testing covering all genes, which would be desirable: Early confirmation (or exclusion) of the diagnosis would be important for the individual patient, as it could help predict whether retinal degeneration can be expected in addition to the congenital hearing impairment.