We used whole-exome sequencing in a cohort of 122 patients with genetically unresolved clinical diagnosis of ADPKD or polycystic liver disease to identify a candidate gene, <i>ALG9</i>, and <i>in vitro</i> cell-based assays of PC1 protein maturation to functionally validate it.
Genetic defects in polycystin-1 or -2 (PC1 or PC2) cause polycystic liver disease associated with autosomal dominant polycystic kidney disease (PLD-ADPKD).
We describe a family with definitely isolated PLD transmitted through three generations and exclude the linkage of the disease to the genetic markers of PKD1 and PKD2, the two main loci responsible for ADPKD.