Atypical haemolytic uremic syndrome (aHUS) is an ultra-rare, potentially life-threatening, genetic disease that leads to the formation of blood clots in small blood vessels throughout the body.1,2 These blood clots can lead to stroke, heart attack, kidney failure and death.
aHUS is caused by a permanent genetic mutation that leads to uncontrolled and excessive activation of complement.3 In healthy individuals, complement is used to attack foreign particles; in patients with aHUS, the body is unable to control the activation of complement. As a result, patients with aHUS face a lifelong risk of sudden, potentially catastrophic, and life-threatening complications1,3 that can occur throughout the body and affect vital organs, including the kidneys, heart and brain.4,5
aHUS can be difficult to diagnose because the disease is so rare that many doctors have never encountered a case of it, or may not have recognised it. Initial signs and symptoms of aHUS include confusion, stomach pain, vomiting, and diarrhoea. aHUS affects both adults and children. In a large group of aHUS patients, about 50 percent were diagnosed under the age of 18.6 Among paediatric patients, aHUS can cause stroke, heart attacks, seizures and high blood pressure.7 One of the most common signs of aHUS is kidney failure. Despite disease management strategies, seventy-nine percent of all patients with aHUS died, required kidney dialysis, or had permanent kidney damage within three years after diagnosis.3
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1. Loirat C, Noris M, Fremeaux-Bacchi V. Complement and the atypical hemolytic uremic syndrome in children. Pediatr Nephrol. 2008;23:1957-1972.
2. Hosler GA, Cusumano AM, Hutchins GM. Thrombotic thrombocytopenic purpura and hemolytic uremic syndrome are distinct pathologic entities: a review of 56 autopsy cases. Arch Pathol Lab Med. 2003;127:834-839.
3. Noris M, Remuzzi G. Atypical hemolytic-uremic syndrome. N Engl J Med. 2009;361:1676-1687.
4. Caprioli J, Noris M, Brioschi S, et al; for the International Registry of Recurrent and Familial HUS/TTP. Genetics of HUS: the impact of MCP, CFH, and IF mutations on clinical presentation, response to treatment, and outcome. Blood. 2006;108:1267-1279.
5. Hirt-Minkowski P, Dickenmann M, Schifferli JA. Atypical hemolytic uremic syndrome: update on the complement system and what is new. Nephron Clin Pract. 2010;114:c219-c235.
6. Noris M, Caprioli J, Bresin E, et al. Relative role of genetic complement abnormalities in sporadic and familial aHUS and their impact on clinical phenotype. Clin J Am Soc Nephrol. 2010;5:1844-1859.
7. Neuhaus TJ, Calonder S, Leumann EP. Heterogeneity of atypical haemolytic uraemic syndromes. Arch Dis Child. 1997;76:518-521.