FH and atypical hemolytic-uremic syndrome: In atypical hemolytic uremic syndrome (aHUS), now referred to as complement-mediated thrombotic microangiopathy (c-TMA),S1 alternative pathway dysregulation is central to pathogenesis, either because of genetic defects (50%–60%) or autoantibodies against factor H (FH) in 6% to 25% (European) and up to 55% (Indian) of cases.1, 2, 3