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An atypical phenotype of macular and peripapillary retinal atrophy caused by a mutation in the RP2 gene
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  1. S S Dandekar1,2,
  2. N D Ebenezer2,
  3. C Grayson3,
  4. J P Chapple3,
  5. C A Egan1,
  6. G E Holder1,
  7. S A Jenkins1,2,
  8. F W Fitzke4,
  9. M E Cheetham3,
  10. A R Webster1,2,
  11. A J Hardcastle2
  1. 1Moorfields Eye Hospital, London, UK
  2. 2Division of Molecular Genetics, Institute of Ophthalmology, University College London, UK
  3. 3Division of Pathology, Institute of Ophthalmology, University College London, UK
  4. 4Division of Visual Science, Institute of Ophthalmology, University College London, UK
  1. Correspondence to: Dr A Webster Division of Molecular Genetics, 11–43 Bath Street, Institute of Ophthalmology, University College London, London EC1V 9EL, UK; Andrew.websterucl.ac.uk

Abstract

Aims: To determine the molecular basis and describe the phenotype of an atypical retinal dystrophy in a family presenting with bilateral, progressive central visual loss.

Methods: Family members were examined. Investigations included Goldman perimetry, electrophysiology, and autofluorescence imaging. Candidate gene screening was performed using SSCP and sequence analysis. The proband’s lymphoblastoid cells were examined for protein expression.

Results: Fundal examination of the proband, his mother, and brother revealed peripapillary and macular atrophy. Autosomal dominant retinal dystrophy was suspected, but less severe disease in the mother led to screening for mutations in X linked genes. A 4 bp microdeletion in exon 3 of the RP2 gene, segregating with disease, was identified. No RP2 protein expression was detected.

Conclusion: The distinct phenotype in this family, caused by this frameshifting mutation in RP2, broadens the phenotypic spectrum of X linked retinitis pigmentosa. The absence of RP2 protein suggests that loss of protein function and not novel gain of function could account for the atypical phenotype. A definitive diagnosis of X linked retinitis pigmentosa permits appropriate genetic counselling with important implications for other family members. Clinicians should have a low threshold for screening RP2 in families with retinal dystrophy, including posterior retinal disease, not immediately suggestive of X linked inheritance.

  • RP2
  • retinitis pigmentosa
  • phenotype
  • ERG, electroretinogram
  • RP, retinitis pigmentosa
  • VA, visual acuity
  • XLRP, X linked retinitis pigmentosa
  • RP2
  • retinitis pigmentosa
  • phenotype
  • ERG, electroretinogram
  • RP, retinitis pigmentosa
  • VA, visual acuity
  • XLRP, X linked retinitis pigmentosa

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