PKD1 and cystic kidney disease: Although deletion of Pkd1, Pkd2, or KIf3a (required for cilia formation) produces renal cysts, with progressive enlargement of fluid-filled renal cysts when the disease reaches the late stage, different mechanisms are involved in cystic development and formation with Pkd1, Pkd2, and Kif3a mutations that may be due to differences in localization and functions within in the kidney (20).