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Hereditary Angioedema (HAE)

Name of disease:

Hereditary Angioedema (HAE)

ICD-10 diagnosis code:

N/A

Causes:

HAE is a rare autosomal dominant genetic disorder (more than 450 known genetic mutations associated with HAE[1]).Most of these mutations affect a key protein in the body called C1 esterase inhibitor (C1-INH). C1-INH regulates the body's production of bradykinin, a locally acting hormone that plays an important role in the control of the dilation and permeability of blood vessels.If the C1-INH is deficient (Type I) or dysfunctional (Type II), bradykinin is released excessively resulting in local swellings. A new form of HAE (Type III) arises independently of a C1-INH deficiency; it is relatively rare and primarily affects women.[2]

Pattern of inheritance:

75% of HAE case are inherited.[3] Children have a 50% chance of inheriting HAE if one of their parents has the condition. However, even without family history, up to 25% of HAE cases result from a spontaneous mutation of the C1-Inhibitor gene at conception.[4]

Prevalence:

The Prevalence is generally believed to be around 1:10,000 to 1:50,000.[1]

Diagnosis:

HAE diagnosis is often mis-diagnosed due to its rarity, substantial variability in disease manifestations, and symptoms can be overlapped with other more common allegic and gastrointestinal conditions. The most common misdiagnoses were angioedema (allergic, 55.7%; nonallergic, 20.5%) and gastrointestinal disorders (appendicitis, 27%; Biliary disorder, 5.4%; GERD, 4.9%; peptic ulcer, 3.8%).[5] There are three specific blood tests used to confirm Hereditary Angioedema Type I or II: C1-Inhibitor quantitative (antigenic), C1-Inhibitor functional, C4. For Type III HAE with Normal C1-INH, genetic testing is required for diagnosis.[4]

Age of onset:

Symptoms of HAE usually appear early in life, most often by age 13, and may increase in severity after puberty.[4]

Common signs and symptoms:

HAE attacks can be spontaneous and last for a few days. Attacks can happen on various body parts, including the hands, feet, face, abdomen (gastrointestinal tract), and throat (airway). Although skin swelling is almost never associated with itching, people with HAE report a “tightness” sensation at the site where the swelling occurs, which can be unpleasant. Facial swelling can be disfiguring. Swelling in the abdomen (intestinal wall) can result in excruciating abdominal pain, nausea, vomiting, and/or diarrhea. Swelling in the throat is the most dangerous because the airway can be closed and, without treatment, can cause death by choking (suffocation).[2]

Available treatments (medicinal and non-medicinal):

On-demand Medications:[1] C1-INH (plasma derived or recombinant) Plasma kallikrein inhibitor Bradykinin B2 receptor antagonist Fresh frozen plasma All HAE patients should have access to at least 2 standard doses on-demand medication for treatment of acute attacks.[1] Preventative Medications: [1] C1-INH approved for short-term and long-term prophylaxis (plasma derived or recombinant) Plasma kallikrein inhibitor[8] Androgen (second line treatment)

Disease management tips:

Most HAE attacks occur spontaneously with no apparent reason or trigger. However, in some cases, a cause can be identified: Emotional stress (23% attacks in 33% patients in clinical trial) Physical trauma (5% attacks in 12% patients in clinical trial) Change in estrogen levels (9% attacks in 11% patients in clinical trial) Other triggers include infections, nontruamatic tissue compression, food(s), prolonged sitting or standing, and dental procedure, etc.[7] An emergency card can be a quick and effective way to let healthcare professionals know that you have a diagnosis of HAE when you arrive at a hospital or care center, and the treatment that should be considered.

References:

Other useful websites:

Patient Organizations: US Hereditary Angioedema Associationhttps://www.haea.org (last access on Apr 25, 2022) HAE Internationalhttps://haei.org/ (last access on Apr 25, 2022) HAE HKhttps://haehk.haei.org/ (last access on Apr 25, 2022) HAE Taiwanhttps://haetaiwan.haei.org/ (last access on Apr 25, 2022) Disease Information: knowHAEhttps://www.knowhae.com/(last access on Apr 25, 2022) Discover HAEhttps://www.discoverhae.com/ (last access on Apr 25, 2022) Local media report disease information (Chinese): 「【遺傳性血管性水腫】突發腫脹窒息可致命罕見遺傳病藥物以急性處理及長期控制為治療目的」News Link(last access on Apr 25, 2022) 「【遺傳性血管性水腫】6旬男受罕見病HAE困擾逾50年　一次喉嚨腫脹險窒息死亡」News Link(last access on Apr 25, 2022) 「Dr. 東：血管性水腫　發病可索命」News Link(last access on Apr 25, 2022)

Acknowledgment

This page is contributed by Takeda Pharmaceuticals (HK) Ltd. ~ C-ANPROM/HK/TAKH/0007 (02/2024)