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Hereditary Angioedema

Last updated May 29, 2018

Approved by: Maulik P. Purohit MD, MPH

Hereditary Angioedema (HAE) is an uncommon, genetically-inherited condition that is passed down in the family.

What are the other Names for this Condition? (Also known as/Synonyms)

  • C1 Esterase Inhibitor Deficiency
  • Hereditary Angioneurotic Edema
  • Quincke’s Disease

What is Hereditary Angioedema? (Definition/Background Information)

  • Hereditary Angioedema (HAE) is an uncommon and severe disorder affecting the body's immune response. It is a genetically-inherited condition that is passed down in the family
  • The body is composed of several proteins and each protein has its own specific function. In this disorder, there is a decreased amount of a particular protein known as C1 esterase inhibitor. The function of this protein is to maintain the fluid that enters and exits the cell
  • A defect in this protein leads to an abnormal buildup of fluid. The excessive accumulation of fluid in the cells creates an obstruction to normal blood flow. Too much fluid causes swelling in various areas of the body such as the face, hands, legs, and feet
  • Depending on the severity of the condition, some individuals may be affected by an obstruction to the airway passage. Airway obstruction is an acute emergency and requires urgent treatment
  • The treatment options for Hereditary Angioedema are limited. The most effective treatment is the administration of C1 inhibitor concentrate, but the availability of the protein is limited. If Hereditary Angioedema is not diagnosed and treated early, the condition can be fatal

Who gets Hereditary Angioedema? (Age and Sex Distribution)

  • Hereditary Angioedema is a genetic disorder that is present at birth. In many individuals, the disorder remains silent until one reaches late childhood or early adulthood
  • The condition can equally affect both males and females.
  • Hereditary Angioedema is observed worldwide. Current research does not indicate that this disorder is more common among a particular racial or ethnic group

What are the Risk Factors for Hereditary Angioedema? (Predisposing Factors)

  • The most important risk factor for Hereditary Angioedema is a positive family history
  • Sometimes, dental procedures and surgeries can also provoke this disorder in susceptible individuals

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Hereditary Angioedema? (Etiology)

  • Hereditary Angioedema arises from a defect or deficiency in the protein C1 esterase inhibitor. The function of this protein is to manage the fluid quantity moving in and out of cells
  • Presently, only an inherited genetic mutation can explain the reason why individuals with a family history of the condition, develop this Hereditary Angioedema

What are the Signs and Symptoms of Hereditary Angioedema?

Individuals with Hereditary Angioedema may be present with:

  • Swelling of the face, legs, arms, and genitalia
  • Neck swelling leading to airway obstruction and deepening of the voice
  • Protruding belly due to excessive fluid, which can cause signs and symptoms such as nausea, diarrhea, or vomiting
  • Stiff skin
  • Headaches and blurred vision
  • Muscle pain and cramping

How is Hereditary Angioedema Diagnosed?

Hereditary Angioedema (HAE) is a medical emergency and immediate treatment needs to be given. This factor needs to be kept under consideration while diagnosing HAE.

  • A complete evaluation of medical and family history along with a thorough physical exam
  • A positive family history is very important to diagnose this condition, as it is an inherited disorder
  • Physical examination will show swelling in various parts of the body that can help make an accurate diagnosis

The following blood tests are usually performed:

  • C1 inhibitor blood level
  • C1 inhibitor functional blood level (If available)
  • Complement component C2 and C4
  • Abdominal ultrasound and CT scan to observe the degree of swelling or obstruction in the intestine

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Hereditary Angioedema?

The most dangerous complication of Hereditary Angioedema is obstruction of airway way, which could be deadly. This condition is a grave emergency and requires immediate medical treatment.

How is Hereditary Angioedema Treated?

Presently, the treatment options for Hereditary Angioedema are very limited. Nevertheless, the treatment may involve:

  • During an acute attack, medications such as pain-relief medications and intravenous fluids are given to manage the symptoms
  • Epinephrine is given in life-threatening reactions
  • The most effective treatment is in administering C1 inhibitor concentrate. However, the availability of this concentrate is limited, and therefore, other medications that directly work on this protein complex is administered such as ecallantide

How can Hereditary Angioedema be Prevented?

  • Currently, there are no specific methods or guidelines to prevent Hereditary Angioedema, since it is a genetic condition
  • Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
  • If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
  • Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

What is the Prognosis of Hereditary Angioedema? (Outcomes/Resolutions)

  • The prognosis for Hereditary Angioedema is based on its severity. It varies from individual to another and depends upon the symptoms that have developed
  • In some cases, HAE can be life-threatening, given the limited treatment options currently available
  • The mortality rate is as high as 15-33% mainly due to laryngeal edema, resulting in obstruction of the airway

Additional and Relevant Useful Information for Hereditary Angioedema:

Within North America the occurrence of Hereditary Angioedema is 1 in 10,000-50,000.

What are some Useful Resources for Additional Information?

References and Information Sources used for the Article:

Helpful Peer-Reviewed Medical Articles:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: May 27, 2015
Last updated: May 29, 2018