Abstract The PAX6 gene on chromosome 11p13 was isolated by positional cloning (Ton et al., 1991) as a strong candidate gene for the human eye anomaly aniridia (OMIM 106210) (Fig. 86–1). The gene was identi(ed within the aniridia subregion of the Wilms’ tumor, aniridia, genitourinary abnormalities, and mental retardation (WAGR, OMIM 194072) contiguous deletion site. Its expression pattern, assessed by RNA in situ hybridization in human and mouse development, is consistent with a role for PAX6 in developmental eye disease, although it is broader than the spectrum of tissues affected in aniridia.