Hereditary Angioedema

Hereditary angioedema is a rare genetic disorder that causes sudden, severe swelling in different parts of your body. The swelling happens because your body does not produce enough of a protein called C1 inhibitor, or the protein does not work correctly. This protein normally keeps your immune system balanced and prevents unwanted swelling.

When C1 inhibitor levels are low or not working, another part of your immune system called the complement system becomes overactive. This leads to the release of substances that cause blood vessels to leak fluid into surrounding tissues. The result is painful, unpredictable swelling episodes that can affect your face, throat, stomach, hands, feet, and other areas.

This condition affects roughly 1 in 50,000 people and runs in families. Episodes can be triggered by stress, illness, injury, or dental procedures, but sometimes they happen without any clear reason. The swelling typically lasts 2 to 5 days and then goes away on its own, but it can be dangerous if it blocks your airway.

• Sudden swelling of the face, lips, tongue, or throat
• Swelling in the hands, feet, or genitals
• Severe abdominal pain and cramping from intestinal swelling
• Nausea, vomiting, or diarrhea during abdominal attacks
• Difficulty breathing or swallowing if the throat swells
• Skin tightness or tingling before swelling begins
• Non-itchy skin swelling that does not respond to antihistamines
• Hoarse voice during throat swelling episodes

Some people experience warning signs like tingling or skin tightness before swelling starts. Episodes can range from mild to life threatening depending on where swelling occurs. Throat swelling is a medical emergency that requires immediate treatment.

Hereditary angioedema is caused by mutations in genes that control the production or function of C1 inhibitor protein. Most commonly, the SERPING1 gene is affected, leading to low levels of C1 inhibitor or a version that does not work properly. Because this is a genetic condition, you inherit it from one or both parents. If one parent has the condition, each child has a 50 percent chance of inheriting it.

Specific triggers can bring on swelling episodes even though the underlying cause is genetic. Common triggers include physical trauma, dental work, infections, stress, certain medications, hormonal changes, and menstruation. Some episodes happen without any identifiable trigger. The severity and frequency of attacks vary widely, even among family members with the same genetic mutation.

Diagnosing hereditary angioedema requires specialized blood tests that measure complement system components. Doctors typically check levels of C1 inhibitor protein, C4 complement component, and C3 complement component. Low levels of C4 are a strong indicator of this condition because the overactive complement system depletes these proteins. Some tests also measure how well your C1 inhibitor protein functions, not just how much you have.

Your doctor will also take a detailed family history since this condition runs in families. Genetic testing can identify the specific mutation causing the condition. Because hereditary angioedema is rare, it is often misdiagnosed as allergies or other conditions at first. Talk to our doctor about specialized testing if you have recurrent unexplained swelling that does not respond to allergy medications.

• Acute attack medications that replace C1 inhibitor or block swelling pathways
• Preventive medications taken regularly to reduce attack frequency
• Short-term preventive treatment before dental work or surgery
• Emergency medications you can keep at home for sudden attacks
• Avoiding known triggers like certain medications and unnecessary trauma
• Wearing medical alert identification in case of emergencies
• Working with an immunologist or allergist experienced in this condition
• Regular monitoring of complement levels and treatment effectiveness