This report describes general characteristics of the group of disorders classified as Usher syndrome (USH). Usher syndrome is a genetically heterogeneous disorder, with multiple genes and mapped loci. A comprehensive list of USH subtypes, as defined by OMIM, can be found by following the link in the "OMIM phenotypic series" section, below. A subset of these are listed in the table below, with links to more detailed reports for subtypes that have been investigated using fly models.
The role of non-muscle myosins in hearing has been investigated using a Drosophila model. Drosophila homologs of three Usher syndrome genes interact together and affect fly hearing; mutations cause a mechanical failure phenotype that appears to be analogous to that seen in the mechanosensory hair cells of vertebrates (FBrf0233094).
[updated Sep. 2017 by FlyBase; FBrf0222196]
Usher syndrome is a condition characterized by partial or total hearing loss and vision loss that worsens over time. The hearing loss is classified as sensorineural, which means that it is caused by abnormalities of the inner ear. The loss of vision is caused by a type of retinitis pigmentosa (RP), which affects the layer of light-sensitive tissue in the retina. [from Genetics Home Reference, Usher syndrome; 2017.01.09]
Usher syndrome is characterized by congenital hearing impairment and varying degrees of unintelligible speech, early retinitis pigmentosa, and vestibular dysfunction; autosomal recessive inheritance is usually observed. Type I is distinguished from type II on the basis of severity of hearing loss and the extent of vestibular involvement. Type I patients are profoundly deaf, whereas type II patients are 'hard of hearing.' Vestibular function is defective in type I patients, whereas type II patients have normal vestibular function (Moller et al., 1989; pubmed:2909824). Patients with type III have progressive hearing loss. [from MIM:601067; 2017.01.09]
