Expanded Phenotype of PAX2-Related Papillorenal Syndrome: A Case Featuring FSGS, Atypical Retinopathy, Cerebellar Hypoplasia, and ADHD

Papillorenal syndrome (PAPRS), or renal coloboma syndrome, is a rare autosomal dominant disorder caused by PAX2 mutations. It classically manifests with renal hypodysplasia and optic nerve anomalies. However, recent literature suggests an expanding phenotypic spectrum. We report a 7-year-8-month-old boy born to consanguineous parents, presenting with stage 4 chronic kidney disease (CKD), nephrotic-range proteinuria, visual impairment, and ADHD. Renal biopsy revealed focal segmental glomerulosclerosis (FSGS), and ocular examination showed bilateral peripheral scalloped chorioretinal atrophy without optic nerve colobomas. Genetic testing confirmed a pathogenic heterozygous PAX2 frameshift mutation (c.69_70insG; p.Val26fs28*), establishing the diagnosis of PAPRS. This case illustrates an expanded phenotype of PAX2-related PAPRS, including FSGS, atypical retinal degeneration, cerebellar hypoplasia, and ADHD. Recognition of such atypical presentations is vital for early diagnosis and multidisciplinary management, especially in resource-limited settings where classic features may be absent.