Atypical aHUS: State of the art

•aHUS is an ultra-rare group of diseases defined by thrombocytopenia, anemia and renal failure.•The majority of patients have genetic abnormalities that impair cell surface control of complement.•Eculizumab, a monoclonal antibody to C5, has drastically reduced the mortality aHUS.•Long-term therapy for aHUS requires further study.

Tremendous advances in our understanding of the thrombotic microangiopathies (TMAs) have revealed distinct disease mechanisms within this heterogeneous group of diseases. As a direct result of this knowledge, both children and adults with complement-mediated TMA now enjoy higher expectations for long-term health. In this update on atypical hemolytic uremic syndrome, we review the clinical characteristics; the genetic and acquired drivers of disease; the broad spectrum of environmental triggers; and current diagnosis and treatment options. Many questions remain to be addressed if additional improvements in patient care and outcome are to be achieved in the coming decade.