Practice question

Mutations in PAX6 transcription factor cause aniridia, congenital absence or severe hypoplasia of iris, accompanied by corneal opacification, cataracts, foveal hypoplasia, and nystagmus. Pax6 continues expression in iris, cornea, retina throughout development maintaining ocular progenitor gene networks. Dominant haploinsufficiency reduces DNA binding to target promoters. Cataract alone typically results from crystallin mutations, retinal detachment from other causes, myopia polygenic. Aniridia represents classic dosage-sensitive phenotype of PAX6 linked to 11p13 deletion, demonstrating pleiotropic eye regulatory role beyond lens induction and corneal maintenance.