Individuals with PAX6-mediated aniridia have insufficient levels of PAX6 protein, which is expressed in the eye, cerebellum, olfactory bulb and throughout the cerebral cortex in early human brain development, but is not expressed cortically in the adult (Walther and Gruss, 1991; Stoykova and Gruss, 1994; Georgala et al., 2011). This evidence concerns the gene PAX6 and isolated aniridia.