Disease at a Glance

Summary
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. In about 60% of aHUS, a genetic change may be identified. The genes associated with genetic aHUS include C3, CD46 (MCP), CFB, CFH, CFHR1, CFHR3, CFHR4, CFI, DGKE, and THBD. Genetic changes in these genes increase the likelihood (predisposition) to developing aHUS, rather than directly causing the disease. In most cases, there is no family history of the disease. In cases that do run in families, predisposition to aHUS is inherited in an autosomal dominant or an autosomal recessive pattern of inheritance.

About Atypical hemolytic uremic syndrome

Many rare diseases have limited information. Currently GARD is able to provide the following information for Atypical hemolytic uremic syndrome:

  • Population Estimate:In the US, there are less than 5,000 with this disease.
  • Symptoms:May start to appear at any time in life.
  • Experts:Patient organizations are available to help find a specialist for this condition.
  • Organizations:Organizations specific to this condition are available to help find support. 

When do symptoms of this disease begin?
The most common ages for symptoms of a disease to begin is called age of onset. Age of onset can vary for different diseases and may be used by a doctor to determine the diagnosis. For some diseases, symptoms may begin in a single age range or several age ranges. For other diseases, symptoms may begin any time during a person's life.
Prenatal Selected
Before Birth
Newborn Selected
Birth-4 weeks
Infant Selected
1-23 months
Child Selected
2-11 years
Adolescent Selected
12-18 years
Adult Selected
19-65 years
Older Adult Selected
65+ years
Symptoms may start to appear at any time in life.

Symptoms

These symptoms may be different from person to person. Some people may have more symptoms than others and symptoms can range from mild to severe. This list does not include every symptom.
This disease might cause these symptoms:
Blood and Blood-Forming Tissue

9 Symptoms

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Blood and Blood-Forming Tissue

The blood and blood-forming tissue includes plasma, red blood cells, white blood cells, platelets, and bone marrow. Common symptoms of problems with the blood or blood forming tissue include fatigue, weakness, shortness of breath, fever, abnormal bleeding, headache, or bruising easily. Diseases of the blood may be diagnosed and treated by a hematologist.

Causes

This section is currently in development. 

Inheritance

All individuals inherit two copies of most genes. The number of copies of a gene that need to have a disease-causing variant affects the way a disease is inherited. This disease is inherited in the following pattern(s):

Autosomal dominant inheritance

Autosomal means the gene is located on any chromosome except the X or Y chromosomes (sex chromosomes). Genes, like chromosomes, usually come in pairs. Dominant means that only one copy of the responsible gene (causal gene) must have a disease-causing change (pathogenic variant) in order for a person to have the disease. Mutation is an older term that is still sometimes used to mean pathogenic variant.

In some cases, a person inherits the pathogenic variant from a parent who has the genetic disease. In other cases, the disease occurs because of a new pathogenic variant (de novo) in the causal gene and there is no family history of the disease.

Each child of an individual with an autosomal dominant disease has a 50% (1 in 2) chance of inheriting the variant and the disease. Typically, children who inherit a dominant variant will have the disease, but they may be more or less severely impacted than their parent. Sometimes a person may have a pathogenic variant for an autosomal dominant disease and show no signs or symptoms of the disease.
Autosomal means the gene is located on any chromosome except the X or Y chromosomes (sex chromosomes). Genes, like chromosomes, usually come in pairs. Dominant means that only one copy of the responsible gene (causal gene) must have a disease-causing change (pathogenic variant) in order for a person to have the disease. Mutation is an older term that is still sometimes used to mean pathogenic variant.

In some cases, a person inherits the pathogenic variant from a parent who has the genetic disease. In other cases, the disease occurs because of a new pathogenic variant (de novo) in the causal gene and there is no family history of the disease.

Each child of an individual with an autosomal dominant disease has a 50% (1 in 2) chance of inheriting the variant and the disease. Typically, children who inherit a dominant variant will have the disease, but they may be more or less severely impacted than their parent. Sometimes a person may have a pathogenic variant for an autosomal dominant disease and show no signs or symptoms of the disease.
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Advocacy and Support Groups

How can a patient organization be helpful?

Patient advocacy and support organizations offer many valuable services and often drive the research and development of treatments for their disease(s). Because these organizations include the life experiences of many different people who have a specific disease, they may best understand the resources needed by those in their community. Although missions of organizations may differ, services may include, but are not limited to:
 

  • Ways to connect to others and share personal stories
  • Easy-to-read information
  • Latest treatment and research information
  • Lists of specialists or specialty centers
  • Financial aid and travel resources
Please note: GARD provides the names of patient organizations for informational purposes only and not as an endorsement of their services. Please contact the organization directly if you have questions about the information or resources they provide.

What do disease-specific organizations do?

Some organizations build a community of patients and families impacted by a specific disease or group of related diseases. These organizations usually have more disease-specific information and services, including helping new members find others who have the same disease.

What do organizations that focus on a medical condition do?

Some organizations build a community of patients and families impacted by a medical condition, like epilepsy, or related conditions, like heart problems, that may also be a symptom in other diseases. These organizations usually have information and services focused more on the medical condition(s), but may also have information about associated diseases.

What do umbrella organizations do?

Rare disease umbrella organizations focus on improving the lives of all those impacted by rare diseases through education and advocacy efforts. Umbrella organizations provide a range of services for patients, families, and disease-specific organizations.

Patient Organizations

5 Organizations

Organization Name

Organization Type

Service

Country

Language

Disease Specific

Atypical Hemolytic Uremic Syndrome

Service

Information

Specialist

Country

United Kingdom

Language

English

EveryLife Foundation for Rare Diseases
https://everylifefoundation.org/
Umbrella

Atypical Hemolytic Uremic Syndrome

Service

Information

Country

United States

Language

English

Spanish

Umbrella

Atypical Hemolytic Uremic Syndrome

Service

Information

Country

United States

Language

English

Umbrella

Atypical Hemolytic Uremic Syndrome

Service

Information

Country

United States

Language

English

National Organization for Rare Disorders
https://rarediseases.org/
Umbrella

Atypical Hemolytic Uremic Syndrome

Service

Information

Research

Country

United States

Language

English

Spanish

5 Organizations

Research

Why is Research Important for Rare Diseases?

Research increases what we know about rare diseases so that people can get a diagnosis more quickly and can know what to expect. Research also helps doctors better understand how well a treatment works and can lead to new treatment discoveries. It may even help improve diagnosis and treatment of more common diseases.

How do you find the right clinical study?

  • Discuss the clinical study with a trusted medical provider before enrolling
  • Review the "Study Description," which discusses the purpose of the study, and "Eligibility Criteria," which lists who can and cannot participate in the study
  • Work with the research coordinator to review the written informed consent, including the risks and benefits of the study
  • Inquire about the specific treatments and procedures, location of the study, number of visits, and time obligation
  • Determine whether health insurance is required and whether there are costs to the participant for the medical care, travel, and lodging
  • Ask questions. Remember, it is okay to decide not to participate in research

For More Information

Current clinical studies can be found by using ClincalTrials.gov. Doctors, other trusted medical professionals, and patient organizations may also be aware of studies. Researchers from participating institutions use the database to search for patients or healthy volunteers who meet their study criteria.

How do you find the right clinical study?

  • Discuss the clinical study with a trusted medical provider before enrolling
  • Review the "Study Description," which discusses the purpose of the study, and "Eligibility Criteria," which lists who can and cannot participate in the study
  • Work with the research coordinator to review the written informed consent, including the risks and benefits of the study
  • Inquire about the specific treatments and procedures, location of the study, number of visits, and time obligation
  • Determine whether health insurance is required and whether there are costs to the participant for the medical care, travel, and lodging
  • Ask questions. Remember, it is okay to decide not to participate in research

For More Information

Current clinical studies can be found by using ClincalTrials.gov. Doctors, other trusted medical professionals, and patient organizations may also be aware of studies. Researchers from participating institutions use the database to search for patients or healthy volunteers who meet their study criteria.

Last Updated: Nov. 8, 2021