April 2011
Volume 52, Issue 14
Free
ARVO Annual Meeting Abstract  |   April 2011
Cone Structure in Patients with Usher Syndrome III Caused by Mutations in the Clarin-1 Gene
Kavitha Ratnam; Hanna Vastinsalo; Sanna Sundquist; Austin Roorda; Eeva-Marja K. Sankila; Jacque L. Duncan
Author Affiliations & Notes
  • Kavitha Ratnam
    Ophthalmology, University of California, San Francisco, San Francisco, California
  • Hanna Vastinsalo
    Medical Genetics, Folkhalsan Institute of Genetics, Helsinki, Finland
  • Sanna Sundquist
    Ophthalmology, University of California, San Francisco, San Francisco, California
  • Austin Roorda
    School of Optometry, University of California, Berkeley, Berkeley, California
  • Eeva-Marja K. Sankila
    Ophthalmology, Helsinki University Eye Hospital, Helsinki, Finland
  • Jacque L. Duncan
    Ophthalmology, University of California, San Francisco, San Francisco, California
  • Footnotes
    Commercial Relationships  Kavitha Ratnam, None; Hanna Vastinsalo, None; Sanna Sundquist, None; Austin Roorda, University of Houston, University of Rochester (P); Eeva-Marja K. Sankila, None; Jacque L. Duncan, None
  • Footnotes
    Support  NIH Grants EY002162, EY014375, Research to Prevent Blindness, Foundation Fighting Blindness, That Man May See, Inc., Hope for Vision The Finnish Eye- and Tissuebank Foundation, De Blindas Vänner rf.
Investigative Ophthalmology & Visual Science April 2011, Vol.52, 4975. doi:
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      Kavitha Ratnam, Hanna Vastinsalo, Sanna Sundquist, Austin Roorda, Eeva-Marja K. Sankila, Jacque L. Duncan; Cone Structure in Patients with Usher Syndrome III Caused by Mutations in the Clarin-1 Gene. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4975.

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Abstract

Purpose: : To study macular structure and function in patients with Usher syndrome type III (USH3A) caused by mutations in the clarin-1 (CLRN1) gene.

Methods: : High-resolution macular images were obtained with Adaptive Optics Scanning Laser Ophthalmoscopy (AOSLO) and spectral domain optical coherence tomography (SDOCT) in 2 patients with USH3A and compared with data from 20 normal subjects. Visual function measures included best-corrected visual acuity (BCVA), kinetic and static perimetry, and full-field electroretinography (ffERG). Mutation analysis of the CLRN1 gene was carried out by sequencing the coding regions.

Results: : Molecular analysis revealed compound heterozygous mutations (p.N48K and p.S188X, a novel C>A change at nucleotide position c.563 which results in an early termination signal at codon 188) in an 18-year-old man, and homozygous mutations (p.N48K) in a 24-year-old woman in the CLRN1 gene. Each patient had excellent BCVA (20/20) and scotomas beginning between 10 degrees (deg) from fixation. FfERG in both patients showed severe outer retinal dysfunction affecting rods to a greater extent than cones. Both patients showed gradual thinning of the outer segment layer and disruption of the inner segment-outer segment (IS-OS) junction beginning 5 deg from fixation. Cones within 4 deg of the fovea had normal density and reflectance, but the central preserved region ended discretely and peripheral photoreceptor degeneration precluded accurate cone-spacing measures.

Conclusions: : Central retinal structure and function were preserved in 2 patients with USH3A caused by mutations in the CLRN1 gene. AOSLO revealed cones where the photoreceptor IS-OS junction was intact, but unambiguous cones were not seen and the IS-OS junction was disrupted in regions corresponding to scotomas, consistent with cone loss. High-resolution images of retinal structure correlated with retinal function in patients with CLRN1 mutations.

Keywords: retinal degenerations: hereditary • imaging/image analysis: clinical • macula/fovea 
© 2011, The Association for Research in Vision and Ophthalmology, Inc., all rights reserved. Permission to republish any abstract or part of an abstract in any form must be obtained in writing from the ARVO Office prior to publication.
Copyright © 2024 Association for Research in Vision and Ophthalmology.
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