Although intra-familial variability in ADPKD is much lower than inter-familial variability and some genotype-phenotype correlations have been reported in the development of ICAs in ADPKD patients, the finding that not all ADPKD individuals of high-risk families develop ICAs indicates that other genetic variants may be involved besides the PKD1 or PKD2 mutations14, 15, 45. This evidence concerns the gene PKD2 and autosomal dominant polycystic kidney disease.