Rare Disease Report

Spotlight on aHUS

JUNE 22, 2016
Andrew Black

About aHUS

 Atypical hemolytic-uremic syndrome (aHUS) is a systemic disease that primarily affects the kidneys. The rare condition is associated with genetic mutations or polymorphisms that result in chronic, uncontrolled activation of the alternative complement pathway. The dysregulated alternative complement pathway activation causes blood clot (thrombi) formation in the glomerular capillaries (groups of small blood vessels of the kidneys) and thickening of the glomerular capillary walls.  Symptoms of aHUS most often include:
  • Nausea and vomiting.
  • Confusion.
  • shortness of breath (dyspnea)
  • Fatigue.
  • Anemia (low red blood cell/platelet count in the blood)
  • Thrombocytopenia (low platelet count in the blood)

The prevalence of aHUS is approximately 2 in 1 million, and it accounts for an estimated 10% of HUS diagnoses. Although many gene abnormalities have been implicated in the pathogenesis of aHUS, 40% of patients have no known mutation. Individuals who have a mutation at birth often do not develop symptoms until adulthood.

aHUS, which is a type of major thrombotic microangiopathy (TMA), can be difficult to distinguish from other TMAs such as thrombotic thrombocytopenic purpura (TTP).


Patients were typically started on plasma exchange as soon as possible after diagnosis, which was continued until hemolysis was controlled. Outcomes with plasmapheresis in aHUS have been mixed, with some patients developing rare but serious complications. Patients were treated with eculizumab. Eculizumab binds to proteins in the blood that can destroy red blood cells.

Developing Treatments

Most recently, Omeros Corporation is working on the development of OMS721. OMS721 is currently in Phase III of trials. OMS721, is Omeros’ lead fully human monoclonal antibody targeting MASP-2. MASP-2 is a key protein involved in activation of the complement system, which is a critical component of the immune system.
These trials are trying to determine if MASP-2 will have a preventive or therapeutic effect in the treatment of a wide range of complement-related diseases like aHUS.

Advocacy Groups

Atypical HUS Foundation serves as dedicated organization for patients, parents, and caregivers to raise concerns and have their opinions voiced about what really matters to those directly dealing with the multiple facets of an aHUS diagnosis. For more information on Atypical HUS Foundation, click here.
aHUS Canada’s goal is to serve as a resource for all Canadians affected by this condition. aHus Canada works on connecting patients and parents across the country to generally raise awareness of aHUS and the difficult issues that come with it. For more information on aHUS Canada, click here.
aHUS Alliance is a team of hard working individuals come together to bring overall awareness to aHUS. They work hard to serve to connect with others and informing all who need to know about aHUS. To learn more about aHUS Alliance, click here.

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