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Phenotypes in defined genotypes including siblings with Usher syndrome.

Eva Malm1, Vesna Ponjavic, Claes Möller

  • 1Department of Ophthalmology, Skåne University Hospital, Lund, Sweden. eva.malm@med.lu.se

Ophthalmic Genetics
|December 23, 2010
PubMed
Summary
This summary is machine-generated.

Usher syndrome exhibits significant visual variability, even among siblings with the same genotype. Comprehensive eye exams reveal diverse patterns of rod-cone degeneration and macular function across Usher syndrome subtypes.

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Area of Science:

  • Ophthalmology
  • Genetics
  • Retinal Diseases

Background:

  • Usher syndrome is a leading genetic cause of combined vision and hearing impairment.
  • Phenotypic variability within Usher syndrome complicates diagnosis and management.
  • Understanding genotype-phenotype correlations is crucial for predicting disease progression.

Purpose of the Study:

  • To characterize visual function in patients with defined Usher syndrome genotypes.
  • To investigate visual function heterogeneity within families, including siblings.

Main Methods:

  • Genetic analysis of 13 Usher syndrome patients from 3 families.
  • Ophthalmological examinations: visual fields, full-field electroretinography (ERG), multifocal electroretinography (mf ERG), optical coherence tomography (OCT).
  • Assessment of visual handicap using an Activities of Daily Living (ADL) questionnaire.

Main Results:

  • Twelve patients genotyped for Usher 1B, 1D, 1F, 2A, 2C, or 3A.
  • ERG confirmed residual cone function in most patients.
  • OCT showed loss of foveal depression in all patients; mf ERG revealed distinct patterns in Usher type 1.
  • One sibling with Usher 2C presented a divergent phenotype with largely normal visual function and imaging.

Conclusions:

  • Visual function evaluation highlights phenotypical heterogeneity in Usher syndrome, both within siblings and across different genotypes.
  • Rod-cone degeneration and macular function vary significantly, underscoring the complexity of Usher syndrome.
  • Detailed ophthalmological assessment is essential for characterizing Usher syndrome phenotypes.