PKD2 and autosomal dominant polycystic kidney disease: Most ADPKD are genetically heterogeneous, with the following two identified causative genes: polycystic kidney disease 1 (PKD1) (OMIM 601313; 16p13.3), responsible for 85% of patients, and polycystic kidney disease 2 (PKD2) (OMIM 173910; 4q22.1), responsible for 15% of patients [3–5].