PKD2 and autosomal dominant polycystic kidney disease: Autosomal dominant polycystic kidney disease (ADPKD) is an adult-onset disease characterized by focal cyst development resulting from heterozygous mutations in PKD1 or PKD2 (Brasier and Henske, 1997; Grantham, 2001; Hughes et al., 1995; Mochizuki et al., 1996).