Does severe ADAMTS13 deficiency in thrombotic microangiopathy rule out complement-mediated atypical hemolytic uremic syndrome.

In evaluating a patient with thrombotic microangiopathy (TMA), it is necessary to rule out thrombotic thrombocytopenic purpura before a diagnosis of atypical hemolytic uremic syndrome (aHUS) is made. There have been reports that mutations of complement factors can coexist with partial A Disintegrin and Metalloproteinase with a ThromboSpondin type 1 motif, member 13 deficiency. Here, we report the case of a 6-year-old girl who was initially diagnosed as nephrotic syndrome and developed TMA after five years of onset of illness. She had poor response to treatment and had multiple relapses due to associated complement factor mutation. Hence, genetic evaluation has to be considered in all children presenting with aHUS.