These early affected ADPKD patients are sometimes clinically indistinguishable from the recessive form ARPKD with mutations in PKHD1. Although much rarer, several further phenocopies are known and mutations in HNF1B (as a master regulator with a major effect on many cystic kidney disease genes) or genes that typically cause other ciliopathies with extrarenal features such as nephronophthisis (NPH) and Bardet-Biedl syndrome (BBS) can mimic PKD especially in the prenatal setting and early childhood [12]. This evidence concerns the gene PKHD1 and Bardet-Biedl syndrome.