Lecture Overview This lecture will address the clinical challenge of classifying, diagnosing, and managing atypical hemolytic uremic syndrome (aHUS). Content will also focus on pathophysiologic concepts and their relationship to current strategies for promoting positive outcomes.   Target Audience This program is designed for physicians (nephrologists, family physicians, obstetricians, pediatricians, and emergency medicine physicians), pharmacists, nephrology nurses, physician assistants, and nurse practitioners.   Learning Objectives Describe the etiologies and pathogenesis of aHUS, as well as its distinction from other TMAs, thereby facilitating a timely and accurate diagnosis.   Apply appropriate methods for evaluating patients with aHUS, including clinical and laboratory assessments, clinically identified triggers, and implications of genetic testing, for the purpose of optimizing renal and overall outcomes.     About the Speaker: Dr. Siedlecki is an Assistant Professor of Medicine at the Harvard Medical School.  His investigational efforts focus on the mechanisms of vascular injury in kidney disease. He oversees a translational clinic practice that studies human endothelial progenitor cells as a therapy for endotheial injury phenotypes such as thrombotic microangiopathy.  This clinic is populated by regional and international referrals which align with a high-risk kidney transplant evaluation clinic which he has supervised for the last ten years.  He contributes to the maintenance and analysis of an international atypical hemolytic uremic syndrome registry as it applies to transplantation and pregnancy subgroups.  He is the principal investigator of multiple clinical trials that aim to advance treatments for patients with complement-mediated disease of the kidney microvasculature. In addition, he works closely with aHUS patient advocacy groups that represent affected families both in the United States and abroad.