A congenital anomaly of the kidney and urinary tract in which one or both kidneys are large, distended by multiple cysts, and non-functional. Global prevalence is not known, but the unilateral form is the most frequent. The disorder frequently presents antenatally at routine ultrasound scan. Bilateral disease is considered a lethal entity and most pregnancies are terminated. The disorder results from disrupted nephrogenesis but the exact pathogenic mechanism is still unknown. Mutations in the HNF1B gene (17q12) are strongly associated with the development of this disease. Most cases are sporadic.

A rare congenital anomaly of the kidney and urinary tract (CAKUT) in which one or both kidneys (unilateral or bilateral MCDK respectively) are large, distended by multiple cysts, and non-functional. Unilateral MCDK is typically asymptomatic if the other kidney is fully functional but may occasionally present with abdominal obstructive signs when the cysts become too large. Bilateral MCDK is considered a lethal entity and neonates present with features of the Potter sequence, severe pulmonary hypoplasia and severe renal failure, and generally die shortly after birth.