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Clinical characterisation of a family with retinal dystrophy caused by mutation in the Mertk gene
  1. M Tschernutter1,
  2. S A Jenkins4,
  3. N H Waseem2,
  4. Z Saihan3,
  5. G E Holder4,
  6. A C Bird4,
  7. S S Bhattacharya2,
  8. R R Ali1,
  9. A R Webster3
  1. 1Division of Molecular Therapy, Institute of Ophthalmology, University College, London EC1V 9EL, UK
  2. 2Division of Molecular Genetics, Institute of Ophthalmology, University College, London EC1V 9EL, UK
  3. 3Division of Inherited Eye Disease, Institute of Ophthalmology, University College, London EC1V 9EL, UK
  4. 4Moorfields Eye Hospital, London EC1V 2PD, UK
  1. Correspondence to: Dr Andrew R Webster Institute of Ophthalmology, Bath Street, London EC1V 9EL, UK; andrew.webster{at}ucl.ac.uk

Abstract

Background/aim: MERTK, a tyrosine kinase receptor protein expressed by the retinal pigment epithelium (RPE), is mutated in both rodent models and humans affected by retinal disease. This study reports a survey of families for Mertk mutations and describes the phenotype exhibited by one family.

Methods: 96 probands with retinal dystrophy, consistent with autosomal recessive segregation, were screened by direct sequencing. A family homozygous for a likely null allele was investigated clinically.

Results: A novel frame shifting deletion was identified in one of 96 probands. Other polymorphisms were detected. The deletion allele occurred on both chromosomes of four affected family members. Electrophysiology demonstrated early loss of scotopic and macular function with later loss of photopic function. Visual acuities and visual fields were preserved into the second decade. Perception of light vision was present in a patient in the fourth decade. A “bull’s eye” appearance and a hyperautofluorescent lesion at the central macula were consistent clinical findings.

Conclusions: Mutations in Mertk are a rare cause of ARRP in humans. The study extends the phenotypic characteristics of this retinal dystrophy and shows distinctive clinical signs that may improve its clinical identification. The moderate severity and presence of autofluorescence implies that outer segment phagocytosis is not entirely absent.

  • ARRP, autosomal recessive retinitis pigmentosa
  • ERGs, electroretinograms
  • FFA, fluorescein angiography
  • HRR plates, Hardy-Rand-Rittler plates
  • OCT, optical coherence tomography
  • PCR, polymerase chain reaction
  • PERG, pattern ERGs
  • RCS, Royal College of Surgeons
  • RP, retinitis pigmentosa
  • RPE, retinal pigment epithelium

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