Genetic Basis of Non-Syndromic Childhood Glaucoma Associated with Anterior Segment Dysgenesis

Twenty causative genes have been reported that cause non-syndromic childhood glaucoma associated with anterior segment dysgenesis. FOXC1, PAX6 and PITX2 are the most well-known, but cases linked to SLC4A11, PITX3 and SOX11 have also been reported. As genetic testing becomes increasingly widespread and rates of molecular diagnosis rise, the extent of phenotypic overlap between the different genetic causes of non-syndromic glaucoma associated with anterior segment dysgenesis is becoming more evident. Taking aniridia as an example, whilst PAX6 mutations remain the predominant cause, variants in CYP1B1, FOXC1, PXDN and SOX11 have also been reported in patients with childhood glaucoma and aniridia. Developments in molecular-based therapies for retinal and corneal disease are advancing rapidly, and pre-clinical studies of gene-based treatments for glaucoma and aniridia are showing promising results. Use of adeno-associated viral vectors for gene delivery is most common, with improvements in intraocular pressure and retinal ganglion cell survival in Tg-MYOCY437H mouse models of glaucoma, and successful correction of a germline PAX6G194X nonsense variant in mice using CRISPR/Cas9 gene editing. This review will explore the actions and interactions of the genetic causes of non-syndromic glaucoma associated with anterior segment dysgenesis and discuss current developments in molecular therapies for these patients.