Vignette #3: Atypical Hemolytic Uremic Syndrome (aHUS)
A 13-month-old male from the Dominican Republic with newly diagnosed high-risk neuroblastoma developed severe hypertension, thrombocytopenia, and acute renal failure after receiving one dose of topotecan and cyclophosphamide as part of induction chemotherapy. Given normal ADAMTS13 function and worsening hemolysis unresponsive to rasburicase and steroids, there was heightened concern for aHUS. Weekly eculizumab infusions were initiated with improvement in the aHUS. Predisposition gene testing revealed a heterozygous VUS in complement factor H (CFH) that has been reported once prior in association with increased susceptibility to HUS, and was predicted by in silico models to be pathogenic9. His aHUS remains in remission.