The majority of ADPKD patients carry a germ-line variant in the PKD1 gene (ADPKD1- MIM173900) on chromosome 16p13, and 15 to 20% of patients harbor a PKD2 variant on chromosome 4q21 (ADPKD2-MIM613095). The gene discussed is PKD2; the disease is autosomal dominant polycystic kidney disease.