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No evidence for locus heterogeneity in Knobloch syndrome
  1. Mohammed A Aldahmesh1,
  2. Arif O Khan2,
  3. Jawahir Y Mohamed1,
  4. Alex V Levin3,
  5. Wadakarn Wuthisiri4,
  6. Sally Lynch5,
  7. K McCreery6,
  8. Fowzan S Alkuraya1,7
  1. 1Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
  2. 2Pediatric Ophthalmology, King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia
  3. 3Pediatric Ophthalmology and Ocular Genetics, Wills Eye Institute, Thomas Jefferson University, Philadelphia, USA
  4. 4Pediatric Ophthalmology and Ocular Genetics, Wills Eye Institute, Philadelphia, USA
  5. 5National Centre for Medical Genetics, Our Lady’s Children’s Hospital, Dublin, Ireland
  6. 6Department of Ophthalmology, Our Lady’s Children’s Hospital, Dublin, Ireland
  7. 7Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
  1. Correspondence to Dr Fowzan S Alkuraya, Department of Genetics, King Faisal Specialist Hospital & Research Center, PO BOX 3354, Riyadh 11211, Saudi Arabia;falkuraya{at}

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To the Editor We previously reported in JMG one case of Knobloch syndrome (KS), offspring of first cousin parents with no detectable mutation in COL18A1. By autozygosity mapping and exome sequencing, we discovered a mutation in ADAMTS18, which we concluded to be probably pathogenic and indicative of locus heterogeneity in KS.1 With this letter, we wish to correct the record by reporting that the case was, indeed, due to a mutation in COL18A1.

KS is an autosomal recessive ocular disorder that is often associated with occipital defects (MIM 267750). The ocular phenotype tends to be highly characteristic and involves both the anterior and posterior segments. Typical eye findings include ectopia lentis, cryptless irides, high myopia and a distinctive vitreoretinal atrophy consisting of diffuse very severe retinal pigment epithelium atrophy with prominent choroidal vessel showing, macular atrophy with or without geographic atrophyand white fibrillar vitreous condensations.2 Occipital defects, ranging from encephalocele to mild occipital cutis aplasia, were formerly considered a requirement for …

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  • Competing interests None.

  • Provenance and peer review Not commissioned; internally peer reviewed.