CFHR4 and hemolytic-uremic syndrome: Absence of both copies of CFHR1 due to homozygous deletion of CFHR3-CFHR1 (delCFHR3-1) or less commonly compound heterozygous deletion of CFHR3-CFHR1 and CFHR1-CFHR4 or homozygous deletion of CFHR1-CFHR4 is associated with an increased relative risk for aHUS as a consequence of the development of FHAAs, referred to as DEAP-HUS, DEficiency of CFHR1 plasma proteins and Autoantibody Positive Hemolytic Uremic Syndrome (15).