What is Hereditary Angioedema?
Hereditary angioedema (HAE) is a rare genetic disorder characterized by recurrent episodes of swelling (edema) of the skin and mucous membranes. The swelling can occur in the hands, feet, limbs, face, genitals, gastrointestinal tract, and airway. The swelling episodes are usually not itchy, but can be painful or disfiguring.
Causes and Mechanism of HAE
HAE is caused by a deficiency of C1-inhibitor, a protein that regulates components of the complement and coagulation systems in the blood. This deficiency results in increased vascular permeability and localized increased production of bradykinin, Hereditary Angioedema leading to capillary leakage. There are two types of HAE – HAE type I is caused by a quantitative C1-inhibitor deficiency while type II is caused by a qualitative or functional C1-inhibitor deficiency despite normal levels. Both result in reduced regulation of bradykinin.
Symptoms and Triggers of HAE Attacks
The most common symptoms are episodes of swelling in the extremities, abdomen, face, and upper airway. Facial swelling is very disfiguring. Abdominal swelling or attacks in the intestinal wall can produce severe abdominal pain, vomiting, and diarrhea. Airway swelling is life-threatening and requires emergency treatment to prevent asphyxiation. Common triggers include stress, minor injuries, infections, medications like estrogen, and in some cases certain foods. Attacks can occur spontaneously without an identifiable trigger.
Diagnosis and Testing
There is no single diagnostic test for HAE. Evaluations should include measuring C4 levels, C1-inhibitor antigenic and functional levels. Genetic testing confirms a gene mutation if available. Diagnosis also relies on assessing family history and response to C1-inhibitor treatment. With a high index of suspicion and appropriate tests, HAE can be distinguished from other conditions that cause swelling such as allergies.
Management Options for Hereditary Angioedema Attacks
For mild to moderate attacks in non-life-threatening areas, antifibrinolytic agents like tranexamic acid are used. For more severe attacks, plasma-derived C1-inhibitor concentrate replacement therapy can rapidly halt progression of swelling. High-dose attenuated androgens such as danazol can be used long-term for prophylaxis to reduce attack frequency in appropriate patients. For prevention of laryngeal attacks, short-term treatment with attenuated androgens or antifibrinolytics is used. Fresh frozen plasma can also be used but is less effective than C1-inhibitor products.
Living with Hereditary Angioedema
With proper prophylactic or on-demand therapy, people with HAE are able to live near-normal lives between attacks. However, angioedema attacks can be painful, disfiguring, socially limiting, and induce fear of asphyxiation. Many have difficulty getting their symptoms believed by medical professionals. Managing disease triggers, carrying rescue medication, working with HAE treatment specialists is important. HAE requires lifelong management that involves balancing preventative and on-demand therapies, managing side effects of treatments, coping with uncertain triggers, and planning ahead for stressful procedures or travel. Support groups help provide community and education for successfully living with HAE.
Burden of Hereditary Angioedema on Business and Economy
HAE imposes a significant burden on the healthcare system and individuals/families affected by it. Attacks sometimes require emergency room visits and hospitalization. Work and school absences are common during severe swelling episodes which last a few days on average. Many miss out on professional and social opportunities due to unpredictable attacks. The rarity and complexity of HAE poses additional challenges in diagnosis and management, leading to excessive healthcare utilization. High drug costs also place a financial burden. Raising awareness among general physicians and public can help reduce delays in diagnosis and treatment that worsen disease burden. Appropriate management leads to cost savings through prevention of expensive emergency care episodes.
Hereditary angioedema is a rare but potentially life-threatening genetic condition that requires sophisticated management options to minimize patient burden from debilitating symptoms. While imposing high costs, effective treatment enables affected individuals to lead fulfilling lives and contributing careers despite lifelong disease management needs. Increasing awareness and optimizing care protocols can help address the challenges of HAE from medical, social and economic standpoints.
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