PKD2 and autosomal dominant polycystic kidney disease: PKD can be mainly categorised into autosomal dominant (ADPKD) and autosomal recessive (ARPKD) (Wilson, 2004), typically induced by germline mutation of PKD1 or PKD2, and PKHD1, respectively (Qian et al., 1996; Pei et al., 1999).