Usher Syndrome, Type IIIA

Alternative Names

  • USH3A
  • Usher Syndrome, Type III
  • USH3

Associated Genes

Clarin 1
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WHO-ICD-10 version:2010

Diseases of the eye and adnexa

Disorders of choroid and retina

OMIM Number

276902

Mode of Inheritance

Autosomal recessive

Gene Map Locus

3q25.1

Description

Usher syndrome is a condition characterized by the gradual loss of both hearing and visual acuity in affected individuals. Hearing loss is progressive, bilateral, sensorineural and in the case of USH3A, post-lingual. Vision loss is caused by retinitis pigmentosa, a gradual deterioration of the retina, resulting in loss of night vision and subsequently peripheral vision. In about half of USH3A cases, patients also suffer from vestibular dysfunction, resulting in difficulties maintaining balance.  

USH3A is a rare subset of Usher syndrome, representing about 2% of all Usher cases. However, due to founder mutations, it is found to be highly prevalent in the Finnish and Ashkenazi Jewish populations. Unlike other forms of Usher syndrome, type III has a later onset; hearing and vision problems usually develop during late childhood or adolescence. As a progressive disorder, the prognosis of USH3A remains bleak; by middle age, most affected individuals suffer from blindness and profound hearing loss.

 

Epidemiology in the Arab World

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Subject IDCountrySexFamily HistoryParental ConsanguinityHPO TermsVariantZygosityMode of InheritanceReferenceRemarks
276902.1.1LebanonMaleYesNo Rod-cone dystrophy; Profound hearing i...NM_174878.3:c.301_305delHomozygousAutosomal, RecessiveAkoury et al, 2011
276902.1.2LebanonMaleYesNo Rod-cone dystrophy; Profound hearing i...NM_174878.3:c.301_305delHomozygousAutosomal, RecessiveAkoury et al, 2011 Brother of 276902.1....
276902.2.1Saudi ArabiaMaleYesYes Rod-cone dystrophy; Sensorineural hea...NM_174878.3:c.254-649T>GHomozygousAutosomal, RecessiveKhan et al. 2017
276902.2.2Saudi ArabiaMaleYesYes Rod-cone dystrophy; Sensorineural hea...NM_174878.3:c.254-649T>GHomozygousAutosomal, RecessiveKhan et al. 2017 Brother of 276902.2....
276902.2.3Saudi ArabiaFemaleYesYes Rod-cone dystrophy; Sensorineural hear...NM_174878.3:c.254-649T>GHomozygousAutosomal, RecessiveKhan et al. 2017 Sister of 276902.2.1
276902.2.4Saudi ArabiaFemaleYesYes Rod-cone dystrophy; Sensorineural hea...NM_174878.3:c.254-649T>GHomozygousAutosomal, RecessiveKhan et al. 2017 Sister of 276902.2.1
276902.3.1Saudi ArabiaUnknown Rod-cone dystrophy; Sensorineural heari...NM_174878.3:c.254-649T>GHomozygousAutosomal, RecessiveKhan et al. 2017
276902.4.1Saudi ArabiaUnknown Rod-cone dystrophy; Sensorineural heari...NM_174878.3:c.254-649T>GHomozygousAutosomal, RecessiveKhan et al. 2017
276902.5.1LebanonFemaleNoNo Rod-cone dystrophy; Sensorineural hear...NM_174878.3:c.188A>CHomozygousAutosomal, RecessiveJaffal et al, 2019b
276902.G.1Saudi ArabiaUnknownYesYes Visual impairmentNM_174878.3:c.254-649T>GHomozygousAutosomal, RecessivePatel et al, 2018 2 family members
276902.G.2United Arab EmiratesUnknown Congenital sensorineural hearing impairm...NC_000003.12:g.150649557_15065992invHomozygousAutosomal, RecessiveElsayed O and Al-Shamsi A. 2022 Two individuals harb...
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