PKD1 and autosomal dominant polycystic kidney disease: ADPKD is mainly caused by mutation in either PKD1 (74–85% of patients) or PKD2 (15–26%) (Rossetti et al., 2007; Barua et al., 2009; Carrera et al., 2016), with PKD2 variants being relatively more frequent in Japan (Kurashige et al., 2015).