Usher syndrome (USH) is an inherited syndromic disorder that is characterized by retinitis pigmentosa (RP) and sensorineural hearing loss with or without vestibular dysfunction. There are three types of USH, with distinct phenotypes [1,2]. Type I (USH1) is the most severe form of USH, characterized by severe congenital deafness, vestibular dysfunction, and prepubertal RP onset. In type II (USH2), hearing loss is less severe, vestibular symptoms are not present, and the onset of RP occurs around puberty. Type III (USH3) shows postlingual progressive hearing loss with or without vestibular symptoms, and the onset of RP is quite variable, as it occurs in people in their 20s to 40s. Currently, 400,000 people worldwide are estimated to be affected by USH. However, only 1% of these cases have been officially identified (https:// www.ushersyndromesociety.org/who-we-are/usher-syndromefacts.html). USH is responsible for 3% to 6% of cases of early childhood deafness. Therefore, early diagnosis, counseling, intervention, and auditory rehabilitation are important to treat USH.
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