Low renin-angiotensin system activity gene polymorphism and dysplasia associated with posterior urethral valves

Obstructive uropathies, including posterior urethral valves (PUVs) and kidney hypodysplasia, are the most frequent cause of renal failure in children. The role of renin-angiotensin system genes in renal and urinary tract development has been observed in experimental models. The aim of this study was to investigate the distribution of angiotensin converting enzyme (ACE), angiotensinogen (AGT) and angiotensin receptor type 1 (ATR1) genetic polymorphisms in children affected by chronic renal failure due to renal hypodysplasia associated with posterior urethral valves or without urethral abnormalities.

The study included 50 children (21 with hypodysplasia associated with PUVs, 7 with obstructive uropathy and 22 with pure hypodysplasia) and 50 healthy subjects matched for sex and geographic origin. ACE ID, AGT TC and ATR1 AC gene polymorphisms were assayed in all patients with standard polymerase chain reaction techniques.

ACE II was expressed more in patients with PUVs compared to those with other dysplasias and controls (43% vs 7% and 10%, respectively, chi-square test p <0.05), while ATR1 AA was significantly less represented in patients with hypodysplasia compared to controls (38% vs 56%, chi-square test p <0.05). ACE DD and AGT genotypes were not distributed differently in patients with PUVs compared to those with other dysplasias and controls.

To our knowledge this is the first report associating severe congenital uropathies and renal hypodysplasia with decreased renin-angiotensin system activity associated with the ACE II genotype and a possible functional imbalance among ATR1 receptors.