One of the two patients in whom no pathogenic mutations in PKD1 or PKD2 were found, except for the synonymous variant of c.11604G > C (p.Thr3868=) in PKD1, had a history of multiple liver cysts that developed in early childhood, but relatively small renal cysts in adulthood, which suggests that genes other than PKD1 and PKD2 could be involved in pathogenicity in this individual. Here, PKD2 is linked to cystic kidney disease.