Illustration of a polycystic kidney (PKD), a cystic genetic disorder of the kidneys. There are two types of PKD: autosomal dominant polycystic kidney disease and the less-common autosomal recessive polycystic kidney disease. PKD is characterized by the presence of multiple cysts. The cysts are numerous and are fluid-filled, resulting in massive enlargement of the kidneys. The disease can also damage the liver, pancreas and, in some rare cases, the heart and brain. The two major forms of polycystic kidney disease are distinguished by their patterns of inheritance.