All are features of familial hemolytic uremic syndromes except:

Familial HUS mostly affecting children, characterized by microangiopathic hemolytic anemia (HA) with presence of fragmented erythrocytes in the peripheral blood smear, thrombocytopenia and acute renal failure. The hemolysis results from an inherited defect external to red cells. Atypical HUS is a severe disease with up to 15% moality in the acute phase and up to 50% of cases progressing to end-stage renal disease. Reference: Harrisons Principles of Internal Medicine, 18th Edition, Page 880