aHUS Triggers

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by Mary Chapman |

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Atypical hemolytic uremic syndrome (aHUS), a chronic multi-organ disease that primarily affects kidney function, may be caused by a genetic mutation coupled with a triggering event. Because aHUS can lead to tissue damage, anemia, and a high risk of bleeding and bruising, it’s important to understand more about the triggers that may be at play in causing the disease’s development.

The following is some information about aHUS triggers that may be helpful.

What are disease triggers?

A trigger, or precipitating event, is generally something that sets off a disease in individuals who are genetically predisposed to developing it. It also could be something that causes a certain symptom to occur in a person who has a disease.

What are the triggers in aHUS?

At least half of people with aHUS have an underlying genetic mutation that, coupled with a triggering event, may cause a flare-up. A genetic mutation alone is usually not enough to cause disease symptoms.

Triggers may include infections, certain medicines, vaccinations, organ transplants, pregnancy, other autoimmune conditions, metabolic conditions, and cancer.

Here is more information about each trigger category:


Infections that can trigger aHUS include diarrheal illnesses caused by a norovirus or bacteria such as Campylobacter upsaliensis, Clostridium difficile, and Fusobacterium necrophorum.

Respiratory infections caused by Bordetella pertussis, Streptococcus pneumonia, and Hemophilus influenza also may trigger aHUS in predisposed individuals.

Other viral triggers may include varicella, cytomegalovirus, influenza H1N1, hepatitis A and C, human immunodeficiency virus (HIV), Coxsackie B virus, Epstein-Barr virus, dengue, HHV6, and human parvovirus B19.

Finally, parasitic infections caused by plasmodium falciparum also may set off aHUS.

Medications and drugs

Among the medications and drugs that may trigger aHUS are cisplatin, gemcitabine, mitomycin, clopidogrel, quinine, interferon-alfa/beta, anti-vascular endothelial growth factor, campath, cyclosporin tacrolimus, ciprofloxacin, and oral contraceptives. Illicit drugs such as cocaine, heroin, and ecstasy also may trigger aHUS.


The hepatitis B vaccine may be a possible aHUS trigger in individuals who have a genetic predisposition for the disease.

Organ transplant

Bone marrow transplants may trigger aHUS in some cases.


In patients carrying a complement gene mutation, pregnancy may cause aHUS.

Autoantibodies and autoimmune conditions

Such triggers can include anticardiolipin and C3Nef, and systemic lupus erythematosus.

Metabolic conditions

Certain metabolic conditions may cause aHUS, including methylmalonic aciduria combined with homocystinuria. Both interfere with the body’s ability to break down proteins.


aHUS may be triggered by certain cancers. These include gastric, breast, prostate, lung, colon, ovarian, or pancreatic cancer, or lymphoma.

Other cases

In rare cases of aHUS, neither gene mutations nor antibodies are present. Some scientists think that there may be other genes that may play a role in the development of the disease.


Last updated: Jan. 11, 2021


aHUS News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.