The kidneys are responsible for the excretion of waste products. Disorders range from those that are present without symptoms, to severe diseases which could be fatal. Congenital disorders include horseshoe kidney and kidney cysts; a single kidney cyst can also occur later in life. The kidneys can also be involved in diseases that affect the whole body: high blood pressure, diabetes mellitus and many autoimmune diseases. If both kidneys cease to function the condition is potentially fatal. Fortunately modern medicine offers kidney transplants and renal dialysis (kidney machine); however, there is a general shortage of kidneys for transplant purposes.