usher_syndrome

Usher Syndrome

often abbreviated as USH

Main Features

  • Retinitis Pigmentosa
  • Sensorineural hearing loss
  • Vestibular disturbances

Eye Findings

  • Retinitis Pigmentosa
    • Pigmentary retinopathy with degeneration of the RPE
    • Optic disc pallor
    • Retinal arteriolar attenuation
    • Symptoms
      • Decreased visual acuity
      • Nyctalopia
      • Peripheral visual field deterioration

Other Findings

  • Progressive retinal degeneration, course depends on the gene affected
    • USH type 1 = profound congenital hearing loss and early vision loss (most severe)
    • USH type 2 = RP by the second decade, moderate to severe congenital hearing loss and no vestibular abnormalities (most severe)
    • USH type 3 = Progressive and variable hearing loss, RP and vestibular abnormalities
    • Significant overlap among subtypes

Etiology

  • Autosomal Recessive inheritance
  • Included in the category of ciliopathy
    • abnormal formation of cilia
  • Major genes affected
    • USH1B (MYO7A)
    • USH1C
    • CDH23
    • USH 1F (PCDH15)
    • USH2A
    • USH3A
  • Usher genes encode for proteins expressed in the inner ear and retina where they provide essential functions for the development of sensory hair cells and photoreceptor maintenance

Epidemiology

  • Prevalence
    • Worldwide 4-17 per 100,000
    • USA 4.4 per 100,000
  • Most common cause for hereditary deafness and blindness
    • 5% of all congenital deafness
    • 18% of retinitis pigmentosa cases

Reference

  • usher_syndrome.txt
  • Last modified: 2025/01/17 10:04
  • by oculoman