Aniridia and deafness: an inherited disorder

Aniridia: current pathology and management

Aniridia is a rare panocular disorder affecting the cornea, anterior chamber, iris, lens, retina, macula and optic nerve. It occurs because of mutations in PAX6 on band p13 of chromosome 11. It is associated with a number of syndromes, including Wilm's tumour, bilateral sporadic aniridia, genitourinary abnormalities and mental retardation (WAGR) syndrome. PAX6 mutations result in alterations in corneal cytokeratin expression, cell adhesion and glycoconjugate expression. This, in addition to stem-cell deficiency, results in a fragile cornea and aniridia-associated keratopathy (AAK). It also results in abnormalities in the differentiation of the angle, resulting in glaucoma. Glaucoma may also develop as a result of progressive angle closure from synechiae. There is cataract development, and this is associated with a fragile lens capsule. The iris is deficient. The optic nerve and fovea are hypoplastic, and the retina may be prone to detachment. Aniridia is a profibrotic disorder, and as a result many interventions--including penetrating keratoplasty and filtration surgery--fail. The Boston keratoprosthesis may provide a more effective approach in the management of AAK. Guarded filtration surgery appears to be effective in glaucoma. Despite our increasing understanding of the genetics and pathology of this condition, effective treatment remains elusive.

Aniridia: recent achievements in paediatric practice

Aniridia is a rare panocular disorder which primarily involves not only the iris, but also the retina, optic nerve, lens and cornea. Visual acuity deteriorates as a result of nystagmus, glaucoma, cataract, corneal opacities and retinal hypoplasia. Aniridia may appear as an isolated disorder, most often familial with autosomal dominance or sporadically in association with at least 12 syndromes. Both familial isolated and Wilms tumour, bilateral sporadic aniridia, genitourinary abnormalities and mental retardation syndrome-associated aniridia have been traced to a mutation of the PAX6 gene on band 11p13. Since genetic diagnosis of this disorder is already possible, counselling affected families should be preceded by karyotype studies and linkage analysis in familial cases of isolated aniridia. In sporadic cases of isolated aniridia or WAGR syndrome, we suggest that PAX6 mutation analysis be employed.