The PAX6 mutation present in an individual with aniridia was determined and phenotypic features of immediate relatives carrying the same mutation investigated. Mutation analysis revealed a novel single base deletion 1410delC in the PAX6 gene in ten affected individuals. Clinical features ranged from total aniridia to very mild anterior segment findings. Other findings included partial aniridia, iris stromal hypoplasia, keratitis, cataract, glaucoma, optic disc anomalies and foveal hypoplasia. It appears that independent modifying factors may underlie the variability of the different phenotypic features of the PAX6 mutation.