Hereditary Angioedema: Here’s Everything You Need To Know!

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Hereditary Angioedema (HAE) is a rare genetic disorder. Recurrent episodes of severe swelling marks. These episodes can affect various body parts. That includes the limbs, face, intestinal tract, and airways.

They are often unpredictable. The condition results from a deficiency or dysfunction of the C1 inhibitor protein. This protein is crucial for regulating the immune system.

External allergens do not cause HAE. It is often misdiagnosed because it resembles common allergic reactions. Swelling attacks can be painful and, when impacting the throat, life-threatening. Treatment focuses on preventing attacks and managing symptoms. It uses advanced therapies to improve patients’ quality of life.

What Are The Causes of Hereditary Angioedema?

Causes of Hereditary Angioedema

Hereditary Angioedema, HAE, is the result of a genetic defect. This problem involves a protein called C1 inhibitor that normally helps to curb inflammation. In HAE, your body may not produce enough of this protein, or the protein may not function correctly.

This, in turn, leads to rapid and painful swelling. It is an inherited disease. The child has a 50 percent chance of inheriting HAE if one of the parents has it. In some cases, HAE can be present in a person without a family history of the condition due to a mutation in the gene.

Signs of Hereditary Angioedema

Hereditary Angioedema is a rare genetic condition. It mainly causes serious and recurrent swelling in different body parts. This state is unique because the swelling does not come with itching.

This differentiates it from an allergic reaction. The swelling itself can be fatal when it affects the gastrointestinal tract. It leads to cramping. It can also be fatal when it affects the airway, resulting in deadly obstructions.

Symptoms mainly occur in childhood. They can become more intense after puberty. The strength of symptoms can be very different between individuals. 

Misdiagnosis of HAE is common. It’s similar to other types of angioedema and allergies. So, people mistakenly get treated with steroids, epinephrine, and antihistamines. However, these drugs don’t work for HAE.

Symptoms of Hereditary Angioedema include 

  • Severe Swelling: Affects hands, feet, limbs, face, intestines, and airway.
  • Pain: Occurs in areas experiencing swelling.
  • Fatigue: A general feeling of tiredness or exhaustion.
  • Muscle Aches: Often accompany the swelling.
  • Tingling Skin: Usually a precursor to swelling episodes.
  • Headaches and Mood Changes: Some individuals report these symptoms.
  • Early Warning Signs: Sudden mood changes, irritability, anxiety, nausea, and extreme tiredness.
  • Non-Itchy Rash: About 25% of patients experience this symptom before or during an attack. 
  • Abdominal Pain and Vomiting: Common, especially when the gastrointestinal tract is involved.
  • Laryngeal Edema: Swelling in the throat area, which can be life-threatening.

Diagnosis of Hereditary Angioedema

To Diagnose if someone has HAE (a swelling disease), doctors look at a few things:

  • 1. Symptoms: People usually start showing signs when they’re kids or teenagers. These can include belly pain that comes back a lot. Swelling that doesn’t get better with usual allergy medicines and breathing problems. Symptoms might get worse if the person takes certain medicines or hormones.
  • 2. Family History: HAE can be passed down in families, so if someone in your family has it, you might be at risk, too. Doctors often suggest that all family members get checked.
  • 3. Blood Tests: Doctors will check your blood for specific markers. There are different types of HAE, and each one shows up differently in these tests. In Type I, some levels are low. In Type II, some are low, and others are normal or high. In Type III, everything might look normal even though the person has HAE.
  • 4. Complement Levels: This is another blood test. Low levels of a thing called C4 can point to HAE. In Type I, another protein (C1 inhibitor) is also low, but it’s normal or high in Type II; it’s just not working right.

Treatment of Hereditary Angioedema

Treatment for Hereditary Angioedema (HAE) has come a long way. There are several options to help keep it under control. Here’s a look at some types of treatment:

➡️ Plasma Kallikrein Inhibitors

  • KALBITOR® (Ecallantide): This injection treats sudden HAE attacks in those 12 and older.
  • ORLADEYO (Berotralstat): This is a pill taken once a day to help prevent HAE attacks in adults and kids 12 and older.
  • TAKHZYR(Lanadelumab-flyo): Another medicine that prevents HAE attacks in people 12 and older. It’s also an injection, and the patient (or their caregiver) can do it at home.

➡️ C1-Inhibitor Concentrates

  • RUCONEST (Conestat alfa): This treatment is for sudden HAE attacks, mainly in adults and older children. It’s administered through a vein, and the user (or their caregiver) can access it.
  • C1 esterase inhibitor (Berinert, Cinryze, Haegarda): Different types of the same medicine treat HAE.

➡️ Bradykinin B2 Receptor Antagonist

  • Icatibant (Firazyr): This medicine also treats sudden HAE attacks.
  • Anabolic Steroids: In the past, danazol, oxandrolone, and stanozolol were used for HAE. They are used less now due to side effects and risks.
  • Supportive Treatments: Sometimes, the patient may need extra oxygen or fluids through a vein during bad attacks.

Managing Hereditary angioedema

During an HAE attack, you need to consider four medications. Some can be used at home, while others require a healthcare professional. During an HAE attack, you need to take other necessary medicines at the same time.

A reminder is necessary that throat swelling can be fatal. If this occurs, seek immediate medical help alongside these meds. First, there is Berinert, a C1 inhibitor. It is administered in a clinic or home setting after symptoms of HAE appear.

Both adults and children use it, and the dose is based on your weight. Next, Firazyr is for adults. You self-inject it subcutaneously into your abdomen during an HAE attack. You may require further doses, but at least three in a day, with a six-hour interval. Ecallantide is intended for use by doctors.

It is injected under the skin at different locations. Allergic reactions are a possible side effect. Finally, adults and teens at home can self-inject another C1 inhibitor, Ruconest. Alternatively, a professional can administer it.

Conclusion

In conclusion, hereditary angioedema is a rare genetic disease. It is mainly characterized by severe and recurrent swelling in various body parts. It arises due to the deficiency of the C1 inhibitor protein. Unlike allergies, HAE swelling does not itch but can be fatal if in the throat or gut.

HAE diagnosis is based on symptoms, family history, and blood tests. Treatment for HAE includes various medications. In HAE attacks, time is of the essence. Take these drugs quickly and seek immediate medical assistance. Remember, throat swelling is serious.

References

  • Craig T, Zuraw B, Longhurst H, et al, eds. Long-term outcomes with subcutaneous c1-inhibitor replacement therapy for prevention of hereditary angioedema attacks. J Allergy Clin Immunol Pract. 2019;7(6):1793-1802.e2. PMID: 30772477 
    https://pubmed.ncbi.nlm.nih.gov/30772477/
  • Zhang Y, Tortorici MA, Pawaskar D, Pragst I, Machnig T, Hutmacher M, Zuraw B, Cicardi M, Craig T, Longhurst H, Sidhu J. Exposure-Response Model of Subcutaneous C1-Inhibitor Concentrate to Estimate the Risk of Attacks in Patients With Hereditary Angioedema. CPT Pharmacometrics Syst Pharmacol. 2018 Mar;7(3):158-165.
    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5869560/

Dr. David G Kiely is a distinguished Medical Reviewer and former General Medicine Consultant with a wealth of experience in the field. Dr. Kiely's notable career as a General Medicine Consultant highlights his significant contributions to the medical field.

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