Phenotypic difference is not unique in rodent models of PKD, for as noted by Fischer et al (2004) [60], the mouse pcy model of NPHP3 was initially proposed as model of ADPKD [61] and the pck rat model, while presenting with an ADPKD phenotype, is due to a mutation in Pkhd1, the rat orthologue of the human gene responsible for ARPKD [62]. The gene discussed is PKHD1; the disease is autosomal recessive polycystic kidney disease.