PAX6 and isolated aniridia: While Pax6 gene mutations in humans are most commonly associated with aniridia (Lee et al., 2020; Tripathy and Salini, 2020), in mice and zebrafish, microphthalmia and severe anterior segment dysgenesis are observed (Takamiya et al., 2015; Yasue et al., 2017; Grant et al., 2020).