Background Vesicoureteric reflux is the most common urological anomaly in children and is a common cause of end stage renal failure and hypertension in children. It usually occurs in isolation and in vast majority of cases it improves on its own. However rarely it can be associated with coloboma and renal hypoplasia, consequent to PAX2 gene mutation.

Case Report We report a case of 14 year old boy, who was under regular paediatric follow-up since the age of 5 month when he had first episode of urinary tract infection. He was put on trimethoprim prophylaxis and micturating cystourethrogram (MCUG) revealed bilateral grade 3 reflux without obstruction at the age of 8 months. He was lost to follow up for 3 years, delaying investigation. Dimercaptosuccinic acid (DMSA) scan at 4 years of age showed small right kidney with no scarring and differential function of 33%. On routine eye check at age of 5 years he was noted to have bilateral optic disc coloboma, however his vision was not affected. He was noted to have mild impairment in renal function at age of 6 yrs with eGFR of 63ml/min/1.73m² which remained stable for next 6 year. During this period he also became significantly obese (body mass index 33) with significant disproportion. He remained normotensive during this period. His renal function started deteriorating for past couple of years with the development of proteinuria. His diagnosis was revisited and was thought to be due to PAX2 gene mutation.

Discussion Paired box (PAX) genes play a critical role in human development and disease. The PAX2 gene is expressed in primitive cells of the kidney, ureter, eye, ear and central nervous system and is required for normal kidney and eye development. Mutation in PAX2 gene has been described in the several families with optic nerve coloboma, renal hypoplasia, mild proteinuria and vesicoureteric reflux.

Conclusion We report this case to raise awareness amongst paediatricians about this uncommon genetic association of vesicoureteric reflux with renal hypoplasia and coloboma which can lead to progressive renal failure.