Genetically testing mechanisms of ocular development and disease

PROJECT SUMMARY AND RELEVANCE Ocular anterior segment dysgenesis (ASD) is a genetically heterogeneous group of developmental disorders affecting the front of the eye. Individuals with ASD have a greatly elevated risk of developing severe and early onset glaucoma that is refractory to treatment. Between 50-75% of patients with ASD develop glaucoma, which occurs at significantly younger ages than in the general population, leading to disproportionately diminished quality of life for these individuals and their families. Despite decades of study, the cellular and molecular details of normal ocular development are still poorly understood, and disease mechanism remain elusive. Mutations in the genes encoding collagen IV alpha 1 (COL4A1) and alpha 2 (COL4A2) cause a multisystem disorder that includes ASD and glaucoma. Importantly, we recently discovered that Col4a1 mutant mice have elevated TGFb signaling and that reducing TGFb signaling partially rescued ASD. We hypothesize that Col4a1 mutation and elevated TGFb signaling affect differentiation of the periocular mesenchyme (POM) – a transient embryonic tissue derived from neural crest cells and paraxial mesoderm. The POM gives rise to structures of the ocular anterior segment including corneal endothelium and stroma, iris stroma, trabecular meshwork, and ciliary muscle. Despite its importance, the small size and transitory nature of the POM has made it difficult to study. This project will apply recent advances in single cell and spatial transcriptomics to overcome this obstacle and enable unprecedented investigation of the cellular and molecular mechanisms of anterior segment development and dysgenesis. The proposed project uses both unbiased and hypothesis driven approaches to answer central questions about where, when, and how pathogenesis arises, reveal other potential disease mechanism, and understand how molecular mechanism(s) might converge with other known genetic causes of ASD in humans. The successful completion of this project will provide foundational knowledge of normal ocular development and novel insights into molecular mechanisms underlying ASD and developmental glaucoma.