In mice, total ACE gene inactivation is compatible with life, whereas in humans it leads to severe hypotension, renal hypoperfusion and renal tubular dysgenesis (RTD), a dramatic kidney disease marked by anuria or severe renal insufficiency at birth, absence of renal proximal tubule differentiation and, most often, perinatal death (18). The gene discussed is ACE; the disease is renal tubular dysgenesis of genetic origin.