['Nephronophthisis (NPHP), which affects multiple organs, is a hereditary cystic kidney disease (CKD), characterized by interstitial fibrosis and numerous fluid-filled cysts in the kidneys. It is caused by mutations in NPHP genes, which encode for ciliary proteins known as nephrocystins. The disorder affects many people across the world and leads to end-stage renal disease. The aim of this study was to determine if the genetic background of the nonmutant female Piebald-Virol-Glaxo (PVG/Seac(-/-)) rat influences phenotypic inheritance of NPHP from mutant male Lewis polycystic kidney rats.', 'Mating experiments were performed between mutant Lewis polycystic kidney male rats with CKD and nonmutant PVG and Wistar Kyoto female rats without cystic kidney disease to raise second filial and backcross 1 progeny, respectively. Rats that developed cystic kidneys were identified. Systolic blood pressure was determined in each rat at 12 weeks of age using the tail and cuff method. After euthanasia, blood samples were collected and chemistry was determined. Histological examination of the kidneys, pancreas, and liver of rats with and without cystic kidney disease was performed.', 'It was established that the genetic background of nonmutant female PVG rats did not influence the phenotypic inheritance of the CKD from mutant male Lewis polycystic kidney rats. The disease arose as a result of a recessive mutation in a single gene (second filial generation, CKD = 13, non-CKD = 39, χ (2) = 0.00, P ≥ 0.97; backcross 1 generation, CKD = 67, non-CKD = 72, χ (2) = 0.18, P > 0.05) and inherited as NPHP. The rats with CKD developed larger fluid-filled cystic kidneys, higher systolic blood pressure, and anemia, but there were no extrarenal cysts and disease did not lead to early pup mortality.'] Does genetic background of nonmutant Piebald-Virol-Glaxo rats influence nephronophthisis phenotypes?