Atypical Hemolytic Uremic Syndrome (aHUS) is a rare, serious condition characterized by the destruction of red blood cells, low platelet counts, and kidney failure. It occurs due to an abnormal activation of the complement system, which is part of the immune response. This can lead to damage in small blood vessels, affecting organs like the kidneys and brain. Symptoms of aHUS may include fatigue, pallor, shortness of breath, and decreased urine output. Diagnosis typically involves blood tests and kidney function assessments. Treatment options may include plasma exchange, medications to inhibit complement activation, and supportive care to manage symptoms and complications.