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Posterior Embryotoxon, Corectopia, and Cerebellar Dysgenesis

Educational Objective
Based on this clinical scenario and the accompanying image, understand how to arrive at a correct diagnosis.
1 Credit CME

An adolescent boy was referred for a routine eye examination with the following medical history: coarctation of the aorta, aortic stenosis, cerebellar hemorrhage, hydrocephalus treated with ventriculoperitoneal shunt, scoliosis due to hemivertebrae, congenital diaphragmatic and umbilical hernia, and hearing loss. Physical examination showed short stature (height in the third percentile) with mild muscle wasting in both lower extremities. Visual acuity was 20/30 OU. He had an esotropia of 30 prism diopters with mild bilateral inferior oblique muscle overaction. External examination showed hypertelorism, bilateral upper eyelid ptosis, and a broad nasal bridge. Slitlamp biomicroscopy disclosed bilateral posterior embryotoxon, iris stromal hypoplasia, and translucent strands extending from the inferior segment of the iris toward the cornea in both eyes, with right corectopia (Figure, A). Intraocular pressures (IOPs) were 11 mm Hg OD and 10 mm Hg OS. Situs inversus of the optic discs and a cup-disc ratio of 0.2 in both eyes was noted. Results of the retinal examination were otherwise normal. SITA (Swedish Interactive Thresholding Algorithm) 24-2 visual field revealed superior arcuate defects in both eyes. Optical coherence tomography (OCT) showed mild peripapillary retinal nerve fiber layer thinning inferiorly in both eyes. Magnetic resonance imaging of the brain disclosed dysgenesis of the left cerebellar hemisphere and vermis (Figure, B). Family history and examination of other family members disclosed no similar abnormalities.

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Axenfeld-Rieger syndrome

D. Genetic testing

This constellation of findings is diagnostic of Axenfeld-Rieger syndrome (ARS). Ocular features observed in ARS include iris stromal hypoplasia, iridogoniodysgenesis, posterior embryotoxon, iris strands bridging the iridocorneal angle to the trabecular meshwork, polycoria, and corectopia. 1 Ocular involvement is usually bilateral but can be asymmetrical.2 The absence of corneal abnormalities distinguishes ARS from other anterior segment dysgenesis disorders, such as Peters anomaly, iris hypoplasia/iridogoniodysgenesis anomaly, or primary congenital glaucoma.2 Ocular malformations in ARS contribute to obstruction of aqueous humor outflow, leading to increased IOP.3 Patients with ARS are at a greater than 50% risk of developing primary open-angle glaucoma.3 Systemic features that accompany ARS include craniofacial abnormalities (maxillary hypoplasia, hypertelorism, and telecanthus), dental anomalies, a redundant umbilical skin, cardiac defects, and hearing loss.4 This autosomal dominant condition is attributed to abnormal neural crest migration.5

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Article Information

Corresponding Author: Michael C. Brodsky, MD, Department of Ophthalmology, Mayo Clinic and Mayo Foundation, 200 First St SW, Rochester, MN 55905 (brodsky.michael@mayo.edu).

Published Online: July 5, 2018. doi:10.1001/jamaophthalmol.2018.0101

Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.

Funding/Support: This study was supported in part by grants from the Knights Templar Eye Foundation and Research to Prevent Blindness.

Role of the Funder/Sponsor: The sponsors had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Additional Contributions: We thank the patient for granting permission to publish this information.

References
1.
Seo  S, Chen  L, Liu  W,  et al.  Foxc1 and Foxc2 in the neural crest are required for ocular anterior segment development.  Invest Ophthalmol Vis Sci. 2017;58(3):1368-1377.PubMedGoogle ScholarCrossref
2.
Seifi  M, Walter  MA.  Axenfeld-Rieger syndrome  [published online October 3, 2017].  Clin Gent. doi:10.0000/cge13148Google Scholar
3.
Rasnitsyn  A, Doucette  L, Seifi  M, Footz  T, Raymond  V, Walter  MA.  FOXC1 modulates MYOC secretion through regulation of the exocytic proteins RAB3GAP1, RAB3GAP2 and SNAP25.  PLoS One. 2017;12(6):e0178518.PubMedGoogle ScholarCrossref
4.
Souzeau  E, Siggs  OM, Zhou  T,  et al.  Glaucoma spectrum and age-related prevalence of individuals with FOXC1 and PITX2 variants.  Eur J Hum Genet. 2017;25(7):839-847.PubMedGoogle ScholarCrossref
5.
Aldinger  KA, Lehmann  OJ, Hudgins  L,  et al.  FOXC1 is required for normal cerebellar development and is a major contributor to chromosome 6p25.3 Dandy-Walker malformation.  Nat Genet. 2009;41(9):1037-1042.PubMedGoogle ScholarCrossref
6.
Strungaru  MH, Dinu  I, Walter  MA.  Genotype-phenotype correlations in Axenfeld-Rieger malformation and glaucoma patients with FOXC1 and PITX2 mutations.  Invest Ophthalmol Vis Sci. 2007;48(1):228-237.PubMedGoogle ScholarCrossref
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