INVS and polycystic kidney disease: The absence of INVS resulted in the constitutive activation of the canonical Wnt pathway, which might be associated with abnormal primary cilia and cyst formation, leading to severe polycystic kidney diseases, multicystic dysplastic kidneys (MCDKs), focal segmental glomerulosclerosis (FSGS), or nephrotic syndrome of the Finnish type (CNF) [15,17].