Why has plasma exchange failed in TRACK syndrome? Lessons from a new variant of the atypical hemolytic uremic syndrome.

Atypical hemolytic uremic syndrome (aHUS) is a rare and life-threatening form of thrombotic microangiopathy, associated with high mortality and morbidity. Most cases present with hemolytic anemia, thrombocytopenia, and renal insufficiency. However, it can have unusual multiple end-organ injuries including extrarenal organ and system involvements such as neurologic, cardiac, gastrointestinal, and respiratory systems. We describe a 4-year-old girl who developed aHUS due to the TSEN2 mutation and had cardiac involvement. She did not benefit from plasma exchange, as stated in previous cases. It should be kept in mind that therapeutic plasma exchange may not be beneficial in some cases of aHUS, especially due to genetic mutations.