Abstract

Usher syndrome (USH) is the most common genetic condition responsible for combined loss of hearing and vision. Balance disorders and bilateral vestibular areflexia are also observed in some cases. The syndrome was first described by Albrecht von Graefe in 1858, but later named by Charles Usher, who presented a large number of cases with hearing loss and retinopathy in 1914. USH has been grouped into three main clinical types: 1, 2, and 3, which are caused by mutations in different genes and are further divided into different subtypes. To date, nine causative genes have been identified and confirmed as responsible for the syndrome when mutated: MYO7A, USH1C, CDH23, PCDH15, and USH1G (SANS) for Usher type 1; USH2A, ADGRV1, and WHRN for Usher type 2; CLRN1 for Usher type 3. USH is inherited in an autosomal recessive pattern. Digenic, bi-allelic, and polygenic forms have also been reported, in addition to dominant or nonsyndromic forms of genetic mutations. This narrative review reports the causative forms, diagnosis, prognosis, epidemiology, rehabilitation, research, and new treatments of USH.

Highlights

  • Human communication is, to a large extent, based on our “far senses”: hearing and vision [1]

  • Usher syndrome (USH) is inherited in an autosomal recessive pattern, and to date, nine causative genes have been identified and confirmed: MYO7A, USH1C, CDH23, PCDH15, and SANS for Usher type 1; USH2A, ADGRV1, and WHRN for Usher type 2; CLRN1 for Usher type 3

  • Clinical USH diagnosis is essentially based on the association between hearing loss and retinitis pigmentosa (RP), where hearing loss is congenital, and RP is apparent in childhood or young adulthood (Table 3)

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Summary

Introduction

To a large extent, based on our “far senses”: hearing and vision [1]. Several pathophysiological studies have demonstrated a number of interactions between actin filaments and microtubules, and the proper functions of actin filaments are essential for microtubules as well as stereovilli in cellular functions From this perspective, when kinocilia are affected in the inner ear and photoreceptors are affected in the retina (inferring direct and indirect tubulin structures), USH can be considered a ciliopathy (Figures 1 and 2) [23,24,25,26]. Further studies are required to confirm this association The scope of this narrative review is to provide an overview of the current clinical and genetic knowledge concerning the epidemiology, diagnosis, prognosis, rehabilitation, and treatment of USH. To the best of our knowledge, an international consensus statement on diagnosis, treatment, rehabilitation, and follow-up of USH has not been published to date

Materials and Methods
Genetics of USH
Epidemiology
Diagnosis and Prognosis
Hearing Loss
Balance
Vision Loss
Prognosis
Usher Type 4?
Rehabilitation
Hearing
Vision
Physical and Psychological Comorbidity
Treatment and Future Perspectives
Findings
Conclusions
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