At these ages small renal cysts were observed in 9 of 19 (47%, 8 Pde1aDel15/Del15 and 11 Pde1aInsA/InsA mice) and 17 of 27 (63%, 20 Pde1aDel15/Del15 and 7 Pde1aInsA/InsA mice) Pde1a mutant compared to 1 of 12 (13%, P = 0.046) and 1 of 10 (10%, P = 0.008) wild-type mice, respectively (Fig 3B and Fig B in S1 File). Here, PDE1A is linked to cystic kidney disease.