PKD2 and cystic kidney disease: Therefore, patients with polycystic kidneys without a family history of polycystic kidneys may carry gene variants associated with cystic kidney disease other than PKD1 and PKD2, including IFT140. However, before the identification of IFT140 as a causative gene of ADPKD, there have been only a few reports regarding the genetic characteristics of a cohort with polycystic kidneys without a family history of polycystic kidneys.9, 10, 11