Genetic and developmental basis of renal coloboma (papillorenal) syndrome

Renal coloboma syndrome, also known as papillorenal syndrome, is characterized by optic nerve anomalies and kidney hypodysplasia. Autosomal dominant mutations in the gene encoding the paired box transcription factor, PAX2, can be identified in nearly half of all patients with this phenotype. The primary ophthalmologic findings include congenital central retinal vasculature absence associated with abnormalities in retinal blood vessel patterning and deeply excavated optic discs. Other published findings include optic nerve hypoplasia, optic nerve cyst, optic nerve pits, retinal coloboma, microphthalmia and scleral staphyloma. Visual acuity ranges from normal to severe impairment. Up to one third of affected patients will develop end-stage renal disease. Mouse and zebrafish with Pax2/pax2a mutations provide developmentally based explanations for the observed phenotypic observations in affected patients.