Pediatric retinal vascular disorders: From translational sciences to clinical practice.

Pediatric retinal vascular diseases are a spectrum with overlapping phenotypes and related genes. Retinal vascular development is biphasic. Vasculogenesis is responsible for the formation of primordial vessels leading to the four major arcades in the posterior retina. Angiogenesis, which is vascular endothelial growth factor dependent, is responsible for the formation of new vessels through budding from existing vessels, forming the peripheral vessels, increasing the capillary density of the central retina, and forming the superficial and deep capillary plexus. This process is controlled by WNT signaling, which is important for cell proliferation, division, and migration. Disorders of WNT signaling, such as familial exudative vitreoretinopathy (FEVR), have overlapping clinical findings. Conversely, pathogenic variants in some of the FEVR-related genes are reported in conditions such as retinopathy of prematurity (ROP), persistent fetal vasculature, and Coats disease. The various overlapping features and underlying genetic basis in the pathogenesis of pediatric retinal vascular developmental diseases suggest that genetic variants may provide a framework or a background for these conditions, upon which further insults can affect the development at any phase (such as prematurity and oxygenation in ROP), influencing and determining the final phenotype.