Polycystic kiney disease (PKD, also known as polycystic kidney syndrome) is a progressive, genetic disorder of the kidneys. It occurs in humans and other organisms. PKD is characterized by the presence of multiple cysts (hence, "polycystic") in both kidneys. The disease can also damage the liver, pancreas, and rarely, the heart and brain. The two major forms of polycystic kidney disease are distinguished by their patterns of inheritance.