PKHD1 and autosomal recessive polycystic kidney disease: Although the exact function of fibrocystin in the formation of the ARPKD phenotype remains unclear, localization of fibrocystin in primary cilia and its interaction with cation channel polycystin-2 suggests its participation in signaling pathways, disruption of which can cause defects in morphogenesis and maintenance of tubular architecture in the organs [8–10].