Usher syndrome is a genetically heterogeneous disorder for which there are 12 independent loci among which there are some known genes, and at least three clinical entities associated deafness and retinitis pigmentosa (RP) with a variable starting age.
Usher syndrome has a prevalence of 3-4/100,000 in the European population.
The differences in auditory and vestibular function are the distinguishing characteristics between the different types of Usher syndrome of the RP is the ophthalmologic manifestation shared by all three types.
Patients with Usher syndrome type I affected congenitally profoundly deaf sensorineural and absence of vestibular function, and usually do not show clinical manifestations of RP birth although the electro-retinograma (ERG) is very upset and there pigmentary degeneration of the retina in ophthalmoscopy.
Patients with Usher syndrome type II, differ from type I to present a less severe congenital hearing loss with preserved vestibular function. The onset of RP overlaps with that of type I.
The patients affected Usher syndrome type III is distinguished from types I and II because have a later onset of both deafness and RP.
Gene or region studied