May 2006
Volume 47, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2006
Detailed Phenotyping of an X–Linked Cone–Rod Dystrophy Pedigree and Exclusion of the CORDX1 and CORDX2 Loci
Author Affiliations & Notes
  • M. Michaelides
    Dept of Molecular Genetics, Institute of Ophthalmology, London, United Kingdom
    Dept of Inherited Eye Disease,
    Moorfields Eye Hospital, London, United Kingdom
  • N.D. Ebenezer
    Dept of Molecular Genetics, Institute of Ophthalmology, London, United Kingdom
  • G.E. Holder
    Dept of Electrophysiology,
    Moorfields Eye Hospital, London, United Kingdom
  • A.G. Robson
    Dept of Electrophysiology,
    Moorfields Eye Hospital, London, United Kingdom
  • A.T. Moore
    Dept of Molecular Genetics, Institute of Ophthalmology, London, United Kingdom
    Dept of Inherited Eye Disease,
    Moorfields Eye Hospital, London, United Kingdom
  • A.J. Hardcastle
    Dept of Molecular Genetics, Institute of Ophthalmology, London, United Kingdom
  • Footnotes
    Commercial Relationships  M. Michaelides, None; N.D. Ebenezer, None; G.E. Holder, None; A.G. Robson, None; A.T. Moore, None; A.J. Hardcastle, None.
  • Footnotes
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Investigative Ophthalmology & Visual Science May 2006, Vol.47, 3286. doi:
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      M. Michaelides, N.D. Ebenezer, G.E. Holder, A.G. Robson, A.T. Moore, A.J. Hardcastle; Detailed Phenotyping of an X–Linked Cone–Rod Dystrophy Pedigree and Exclusion of the CORDX1 and CORDX2 Loci . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3286.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: : To characterise the phenotype of an X–linked retinal dystrophy identified in a three–generation British family and to determine the underlying molecular genetic basis.

Methods: : Five affected individuals and two obligate carrier females underwent ophthalmological examination, colour vision testing, colour fundus photography, autofluorescence imaging, and electrophysiological assessment. Five unaffected subjects also underwent clinical assessment. DNA was extracted for mutation screening of RPGR and haplotype analysis.

Results: : Affected subjects complained of reduced central vision starting in the first decade, with subsequent gradual deterioration of visual acuity and colour vision. Patients were myopic, had mild to moderate photophobia, and several were aware of improved vision in mesopic conditions. A range of macular appearances were seen, varying from mild retinal pigment epithelial changes to extensive macular atrophy. Autofluorescence (AF) imaging revealed decreased AF corresponding to areas of atrophy seen ophthalmoscopically in older individuals, with a macular ring of increased AF seen in a younger subject. All five affected subjects had abnormal pattern ERGs consistent with macular dysfunction. Four of these patients had evidence of generalised retinal dysfunction, with the cone system more affected than the rod. Both obligate carriers had a normal clinical examination, AF imaging and electrophysiological assessment. Direct sequencing of RPGR failed to identify any disease–causing mutations. Haplotype analysis excludes CORDX1 (caused by mutations in RPGR ORF15) and CORDX2 as disease loci in this family.

Conclusions: : We have identified a three–generation British family with X–linked cone–rod dystrophy. The only known X–linked cone/cone–rod dystrophy gene, RPGR, has been excluded as the causative gene in this family by sequence and haplotype analysis. Extensive haplotype and linkage analysis is underway to determine the critical disease interval in this family.

Keywords: retina • genetics 
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