PRKD1 and autosomal dominant polycystic kidney disease: Somatic mutations of the second non-mutated PKD allele are supposed to play a role in the initiation of cyst formation in ADPKD patients, and even though somatic mutation rates may differ between organisms, the short lifespan of rodents might thus explain the only very mild phenotype observed as a consequence of heterozygous Pkd mutations [18,198].