PAX2 and holoprosencephaly: Among the emblematic genes implicated in ocular morphogenesis and whose mutations cause ocular malformations, we can quote PAX6 (MIM*607108) as the “master” gene in eye development whose mutations are mainly linked to a panocular disorder called aniridia; SHH (MIM*600725) responsible for the division of the eye field into two optic vesicles for which pathogenic variants are associated with cyclopia (holoprosencephaly spectrum); or PAX2 (MIM*167409) which is essential for optic stalk formation and closure of the choroid fissure in which pathogenic variants are responsible for coloboma.