Atypical hemolytic-uremic syndrome (aHUS) is a disease that causes abnormal blood clots to form in small blood vessels in the kidneys. These clots can cause serious medical problems if they restrict or block blood flow, including hemolytic anemia, thrombocytopenia, and kidney failure. It can occur at any age and is often caused by a combination of environmental and genetic factors. Genetic factors involve genes that code for proteins that help control the complement system (part of your body’s immune system). Environmental factors include certain medications (such as anticancer drugs), chronic diseases (e.g., systemic sclerosis and malignant hypertension), viral or bacterial infections, cancers, organ transplantation, and pregnancy. Most cases are sporadic. Less than 20 percent of all cases have been reported to run in families. When the disorder is familial, it can have an autosomal dominant or an autosomal recessive pattern of inheritance.[1][2]
Atypical hemolytic-uremic syndrome differs from a more common condition called typical hemolytic-uremic syndrome. The two disorders have different causes and different signs and symptoms.[2]
The Human Phenotype Ontology (HPO) provides the following list of features that have been reported in people with this condition. Much of the information in the HPO comes from Orphanet, a European rare disease database. If available, the list includes a rough estimate of how common a feature is (its frequency). Frequencies are based on a specific study and may not be representative of all studies. You can use the MedlinePlus Medical Dictionary for definitions of the terms below.
| Signs and Symptoms | Approximate number of patients (when available) |
| Acute kidney injury | - |
| Anuria | - |
| Autosomal dominant inheritance | - |
| Autosomal recessive inheritance | - |
| Cognitive impairment | - |
| Coma | - |
| Decreased serum complement C3 | - |
| Decreased serum complement factor B | - |
| Decreased serum complement factor H | - |
| Decreased serum complement factor I | - |
| Diarrhea | - |
| Dysphasia | - |
| Elevated serum creatinine | - |
| Fever | - |
| Hemiparesis | - |
| Hemolytic-uremic syndrome | - |
| Hyperlipidemia | - |
| Hypertension | - |
| Increased blood urea nitrogen | - |
| Microangiopathic hemolytic anemia | - |
| Purpura | - |
| Reticulocytosis | - |
| Schistocytosis | - |
| Seizures | - |
| Thrombocytopenia | - |
The resources below provide information about treatment options for this condition. If you have questions about which treatment is right for you, talk to your healthcare professional.
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Nonprofit support and advocacy groups bring together patients, families, medical professionals, and researchers. These groups often raise awareness, provide support, and develop patient-centered information. Many are the driving force behind research for better treatments and possible cures. They can direct people to research, resources, and services. Many groups also have experts who serve as medical advisors. Visit their website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.
Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.
These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.
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My brother in law has just been diagnosed with atypical hemolytic-uremic syndrome (aHUS) and has suffered kidney failure. We have found out his cousin also has it. One of our concerns is for my husband and our two children. Is there a way that they can be tested to rule out aHUS? See answer
