AVPR2 and autosomal recessive polycystic kidney disease: There are several possible pathophysiological mechanisms of impaired kidney concentrating capacity in ARPKD, such as structural alteration of the distal tubules and collecting ducts due to cyst formation, alterations in vasopressin receptor (V2R), ion channels such as epithelial sodium channels (ENaC) or aquaporins (AQPR) [33].