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A new phenotype of recessively inherited foveal hypoplasia and anterior segment dysgenesis maps to a locus on chromosome 16q23.2–24.2.
  1. B Pal1,
  2. M D Mohamed1,
  3. T J Keen1,*,
  4. G A Williams1,
  5. J A Bradbury2,
  6. E Sheridan3,
  7. C F Inglehearn1
  1. 1Molecular Medicine Unit, University of Leeds, Leeds, UK
  2. 2Department of Ophthalmology, Bradford Royal Infirmary, Bradford, UK
  3. 3Yorkshire Regional Genetics Service, St James’s University Hospital, Leeds, UK
  1. Correspondence to:
 Professor C Inglehearn
 Vision Research Group, Molecular Medicine Unit, Clinical Sciences Building, St James’s University Hospital, Leeds LS9 7TF, UK;

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The phrase anterior segment dysgenesis (ASD), also sometimes known as anterior segment ocular or mesenchymal dysgenesis (ASOD or ASMD, OMIM #107250), was first used in 1981 by Hittner and colleagues to describe a range of developmental defects in structures at the front of the eye.1 These defects are thought to result from abnormal migration or differentiation of the neural crest derived mesenchymal cells that give rise to the cornea, iris, and other components of the anterior chamber during eye development.2,3 Conditions falling within the ASD spectrum include aniridia, posterior embryotoxon, Axenfeld’s anomaly, Reiger’s anomaly/syndrome, Peters’ anomaly, and iridogoniodysgenesis. Aniridia (OMIM #106210) ranges from almost complete absence of the iris, through enlargement and irregularity of the pupil mimicking a coloboma, to small slit-like defects in the anterior layer visible only with a slit lamp. In Axenfeld’s anomaly (OMIM #109120), the Schwalbe’s line is prominent and centrally displaced (posterior embryotoxon) with peripheral iris strands fused to it. Eye signs in Rieger’s anomaly (OMIM #109120) patients may include malformations of the anterior chamber angle and aqueous drainage structures (iridogoniodysgenesis), microcornea, iris hypoplasia, eccentric pupil (corectopia), iris tears (polycoria), and iridocorneal tissue adhesions traversing the anterior chamber angle.4,5 In Reiger’s syndrome (OMIM #180500), patients have ASD in association with underdeveloped or misshapen teeth (hypodontia) and may also have hearing loss, heart defects and skeletal abnormalities. Peters’ anomaly (OMIM #604229) consists of a central corneal leucoma, absence of the posterior corneal stroma and Descemet membrane, and varying degrees of iris and lenticular attachment to the posterior cornea. All of these conditions carry with them an increased risk of glaucoma owing to abnormalities in the Schlemm’s canal and trabecular meshwork.

Human ASD phenotypes are genetically heterogeneous,6 resulting from mutations in seven different transcription factor genes (PAX6, PITX2, PITX3, FOXC1, FOXE3, …

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  • * Present address, Department of Anatomy and Cell Biology, University of Bergen, Norway

  • This study was supported by Wellcome Trust Grants 071590 and 073477.

  • Conflicts of interest: none declared

  • The first two authors contributed equally to this work.