Mondo Description Congenital primary aphakia (CPA) is characterised by an absence of the lens. The prevalence is unknown. CPA can be associated with variable secondary ocular defects (including aplasia/dysplasia of the anterior segment of the eye, microphthalmia, and in some cases absence of the iris, retinal dysplasia, or sclerocornea). CPA results from early developmental arrest, around the 4th-5th week of embryogenesis, which prevents the formation of any lens structure. Mutations in the FOXE3 gene were identified in three affected siblings born to consanguineous parents.

Uniprot Description A form of anterior segment dysgenesis, a group of defects affecting anterior structures of the eye including cornea, iris, lens, trabecular meshwork, and Schlemm canal. Anterior segment dysgeneses result from abnormal migration or differentiation of the neural crest derived mesenchymal cells that give rise to components of the anterior chamber during eye development. Different anterior segment anomalies may exist alone or in combination, including iris hypoplasia, enlarged or reduced corneal diameter, corneal vascularization and opacity, posterior embryotoxon, corectopia, polycoria, abnormal iridocorneal angle, ectopia lentis, and anterior synechiae between the iris and posterior corneal surface. Clinical conditions falling within the phenotypic spectrum of anterior segment dysgeneses include aniridia, Axenfeld anomaly, Reiger anomaly/syndrome, Peters anomaly, and iridogoniodysgenesis. Some ASGD2 patients show congenital primary aphakia, a defect caused by eye development arrest around the 4th-5th week of gestation. This prevents the formation of any lens structure and leads to severe secondary ocular anomalies, including a complete aplasia of the anterior segment of the eye. In contrast, in secondary aphakic eyes, lens induction has occurred, and the lens vesicle has developed to some degree but finally has progressively resorbed perinatally, leading, therefore, to less severe ocular defects. ASGD2 inheritance is autosomal recessive.