Adult polycystic kidney disease: a disorder of connective tissue?

Adult polycystic kidney disease (APCKD) is one of the most common serious inherited disorders. Many affected patients succumb to the renal and non-renal manifestations of this autosomal dominant disease. The disease is characterized by cyst formation in several organs, most obvious of which is in the renal parenchyma. Other features associated with the disease include hepatic fibrosis, hepatic, pancreatic and splenic cyst formation, Berry aneurysms, colonic diverticulae, hernias and cardiac valvular disorders. Rupture of Berry aneurysm is a sudden and often fatal manifestation in some unsuspected cases of APCKD. We recently examined one surgically removed kidney from a 15-year-old male patient with APCKD. In addition to the classical cystic change, extensive changes in renal parenchymal matrix and vasculature are also present. The excessive and weak matrix may contribute to dilatations of both renal tubules giving rise to cysts and the blood vessels. Our findings suggest that APCKD may be a connective tissue disorder in which alteration of extracellular matrix may be a common denominator for the manifestations and organ pleotropism of APCKD.