Polycystic kidney is divided into adult type polycystic kidney and infantile type polycystic kidney. Adult polycystic kidney is an autosomal dominant disorder. Adult polycystic kidney is common, but infantile polycystic kidney is rare. Infantile polycystic kidney, an autosomal recessive polycystic kidney disease, affects both kidney and liver development (hypoplasia of the portal system). Neonatal mortality is high and many surviving individuals, in addition to multiple class II cysts in both kidneys and manifestations of renal failure, often have portal hypertension as a prominent symptom. The disease often dies shortly after birth, with only a very few milder types surviving into childhood or even adulthood.