La sindrome di Usher

Usher syndrome (US) is an autosomal recessive disorder characterized by congenital bilateral sensorineural hearing loss and progressive loss of vision secondary to retinitis pigmentosa. US can be divided into several clinical types. Types 1 and 2 are the most common subtypes. Type 3, which is associated with progressive hearing loss, is more uncommon. The hallmark of US type 1 is congenital impairment of the vestibular system. Type 1 is characterized by severe to profound sensorineural hearing loss, absent vestibular function, and RP. Type 2 is characterized by moderate to severe sensorineural hearing loss, normal vestibular function and RP. Although clinically there are two main types of US, research has proven that genetic heterogeneity exists within each type. Three genes for US type I and two genes for US type 2 have been identified. Genetic heterogeneity also limits the use of DNA markers in the early diagnosis of US. At the present time, children with US are typically not diagnosed until adolescence or your adulthood. Delay in diagnosis often occurs because of the insidious nature of the visual abnormalities. This paper describes of clinical criteria recommended for the diagnosis of US and the main disorders with deafness and low vision associated.