PAX6 and microphthalmia: In addition to varying degrees of iris defects, other associated ocular phenotypes (e.g. microphthalmia, optic nerve anomalies, and anterior segment dysgenesis) [40, 41] and systemic abnormalities (e.g. hormonal, metabolic, gastrointestinal, genitourinary, and neurologic disorders) [3–9] have been reported in some cases with PAX6 mutations.