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Mentions: The patient was referred to our institute when she was four years old with an uncertain diagnosis of ARS versus aniridia. Shortly before the referral, she was found to have an increased intraocular pressure (IOP) in both eyes: 27 mmHg in the right and 46 mmHg in the left, and was started on glaucoma medications. When she was using timolol and dorzolamide as fixed combination and bimatoprost eye drops in both eyes, the IOP measured by Goldmann tonometry was 14 mmHg in the right and 32 in the left. Her spectacle-corrected vision was 20/80 in the right and 20/40 in the left, with moderate hyperopia in the right and mild myopia in the left. The right eye was amblyopic, and was undergoing occlusion therapy. She has no strabismus or nystagmus. Slit lamp examination of the right eye revealed polycoria, adhesion of iris strands to the peripheral cornea, and posterior embryotoxon. (Figure 1) Examination of the left eye revealed a small iris stub resembling aniridia, and a similar appearance was noted on an old photograph taken when she was 3 months old (Figure 2 and Figure 3).Corneal pachymetry was 664 microns in the right and 683 microns in the left. The horizontal corneal diameter measured 11 mm in both eyes. Axial length by ultrasonic measurement was 21.78 mm in the right eye and 24.46 mm in the left eye. Gonioscopy revealed extensive iris strands bridging the iridocorneal angle to the trabecular meshwork in the right and complete angle closure by the stub of the iris in the left. Optic disc examination revealed a cup/disc ratio of 0.30 in the right eye and 0.95 in the left, and there was no retinal pathology (Figure 4 and Figure 5). Further physical examination revealed a flat midface, hypodontia with lack of an upper incisor, and redundant periumbilical skin (Figure 6 and Figure 7). Ultrasonic examination of kidneys was normal and there was no cardiac abnormality. She has normal intelligence. Other family members including both parents and a younger brother were examined and no similar anomaly was noted. However, the maternal uncle has Russell-Silver syndrome and was not available to be examined.
Asymmetric phenotype of Axenfeld-Rieger anomaly and aniridia associated with a novel PITX2 mutation
Bottom Line: Asymmetric anterior segment characteristics of patients with ARS were compared with reported cases in the literature.A heterozygous C>T nucleotide substitution was identified in exon 4 of the pituitary homeobox 2 (PITX2) gene, resulting in the replacement of a glutamine codon (CAG) with a stop codon (TAG) at amino acid position 67.The current case undermines the advantage of genetic testing to correctly diagnose a rare disease.
Affiliation: Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA. firstname.lastname@example.org
Purpose: To evaluate the asymmetry of the anterior segment phenotype between the two eyes of a patient with Axenfeld-Rieger syndrome (ARS).
Methods: The entire database of a tertiary glaucoma practice was screened for patients with ARS. The medical records of patients with ARS were reviewed. The clinical characteristics of ocular examination of the two eyes of each patient were recorded and compared. Dental and medical information were also reviewed where available. The anterior segment phenotype was tabulated to assess asymmetry. Asymmetric anterior segment characteristics of patients with ARS were compared with reported cases in the literature.
Results: Eight patients with ARS were identified from screening of more than 5,000 patients of a tertiary glaucoma practice. All patients had Axenfeld-Rieger anomaly in both eyes except one patient presented with an asymmetric phenotype of the anterior segment with features of Axenfeld-Rieger anomaly in one eye, but aniridia in the other eye. This patient had non-ocular findings including flat midface, hypodontia with lack of an upper incisor, and redundant periumbilical skin, typical for ARS. A heterozygous C>T nucleotide substitution was identified in exon 4 of the pituitary homeobox 2 (PITX2) gene, resulting in the replacement of a glutamine codon (CAG) with a stop codon (TAG) at amino acid position 67. This mutation is denoted c.199C>T at the cDNA level or p.Gln67Stop (or Q67X) at the protein level. Only three cases with asymmetric anterior segment phenotype between the two eyes of a patient with AGS have been reported in the literature.
Conclusions: Variability in phenotype may occur between the two eyes of an individual affected by ARS. The current case undermines the advantage of genetic testing to correctly diagnose a rare disease.
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