PAX6 and aniridia: In contrast, Shh inhibits Pax6, restricting its expression to the distal optic cup, which is critical for lens induction from the surface ectoderm.50,51 Human mutations in PAX6 are most commonly associated with aniridia (OMIM 706108), an autosomal dominant congenital eye disease characterized by cataract, limbal stem cell deficiency, glaucoma, and hypoplasia of the iris, optic nerve, and fovea.