A rare congenital disorder where some or all of the bile ducts fail to develop or develop abnormally. As a result of this, bile is not able to drain from the liver. Unless the atresia can be treated, secondary biliary cirrhosis (a serious liver disorder) will develop and can prove fatal. Symptoms include jaundice, usually beginning a week after birth, and the passing of dark urine and pale faeces. Treatment is by surgery to bypass the bile ducts. If the jaundice reoccurs or this fails a liver transplant is required.