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It is estimated that approximately one third of patients with sporadic aniridia will develop a Wilms tumor, and approximately half of patients with aniridia, genitourinary anomalies (e.g., hypospadias), and mental retardation will develop a Wilms tumor. The association with genitourinary anomalies and mental retardation is known as WAGR Syndrome. Most patients have prominent lips and macrognathia. Other features may include congenital cataracts, nystagmus, ptosis, and blindness. The presence of ptosis and generalized hypotonia in a subgroup of patients suggests a susceptibility to malignant hyperthermia.

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Estimated between 1:60,000 and 1:100,000 live births. All races are affected.

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Both hereditary and sporadic forms exist. Approximately 30% of cases arise spontaneously. The usual form of inheritance is an autosomal dominant trait, but autosomal recessive transmission has been suggested for the rare Gillespie syndrome. There are two genetic loci for aniridia: aniridia type 1 (AN1) results from a defect on the short arm of chromosome 2; aniridia type 2 (AN2) has been related to a defect on 11p13. Aniridia as an isolated ocular malformation is an autosomal dominant disorder caused by a mutation in the PAX6 (paired box gene family) gene located on 11p13. Although patients with a positive family history for aniridia do not have an increased risk for Wilms tumor, patients without a positive family history for aniridia (sporadic cases) have a 30% risk of developing Wilms tumor.

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Aniridia is related to a primary arrest in the neuroectodermal development and a secondary disturbance of the three neural crest waves from the mesenchyme. Functional development of the anterior segment is a complex interrelationship between neural ectoderm and the neural crest waves mesenchyme. Cellular and/or biochemical aberrations may result in malformation or regression of different layers of the anterior segment of the eye. The iris stroma is hypoplastic, and the extent of the defect ranges from slit-like lesions of the iris stroma only visible under slitlamp examination to coloboma-like defects and almost complete absence of the iris stroma. The root of the iris, however, is most often visible on gonioscopy. Aniridia has been produced experimentally in mice with maternal vitamin A deficiency.

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At birth, the iris is reduced to a small tube. In general, vision is decreased, with numerous other contributing anomalies including light scatter, corneal and lenticular opacities, severe glaucoma, nystagmus, optic nerve agenesis, and foveal hypoplasia.

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Aniridia and Absent Patella

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This combination has been reported in three generations of one family. Bilateral cataracts and glaucoma complicated by aniridia and hypoplastic or aplastic patellae.

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Typical presentation is discovery of fixed dilated pupils in a hypotonic infant. Neurologic signs include marked motor delay, hypotonia, disabling ataxia, and usually mental retardation. The combination with tetralogy of Fallot and/or cardiomyopathy has been reported.

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Aniridia, Microcornea, and Spontaneously Reabsorbed Cataract

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This combination has been described in three generations ...

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