Bi-allelic mutations in renin-angiotensin system genes, associated with renal tubular dysgenesis, can also present as a progressive chronic kidney disease

Background: Bi-allelic loss of function variations in genes encoding proteins of the renin-angiotensin system (AGT, ACE, REN, AGTR1) are associated with autosomal recessive renal tubular dysgenesis, a severe disease characterized by the absence of differentiated proximal tubules leading to fetal anuria and neonatal end-stage renal disease.

Case-diagnosis/treatment: We identified bi-allelic loss of function mutations in ACE, the gene encoding angiotensin-converting enzyme, in 3 unrelated cases displaying progressive chronic renal failure, whose DNAs had been sent for suspicion of juvenile hyperuricemic nephropathy, nephronophthisis, and cystic renal disease, respectively. In all cases, patients were affected with anemia whose severity was unexpected regarding the level of renal failure and with important polyuro-polydipsia.

Conclusions: Bi-allelic loss of function mutation of ACE can have atypical and sometimes late presentation with chronic renal failure, anemia (out of proportion with the level of renal failure), and polyuro-polydipsia. These data illustrate the usefulness of next generation sequencing and "agnostic" approaches to elucidate cases with chronic kidney disease of unknown etiology and to broaden the spectrum of phenotypes of monogenic renal diseases. It also raises the question of genetic modifiers involved in the variation of the phenotypes associated with these mutations.