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Hereditary Angioedema (HAE) patients experience recurrent episodes of swelling in the hands, feet, face, gastrointestinal tract, genitals, and larynx (throat) that can last from two to five days. The frequency of and severity of attacks varies dramatically among patients, and even among those within the same kindred. A survey of HAE patients in Italy (over 500 identified and followed) revealed that slightly less than one half of untreated patients have more than one attack per month, and forty percent have 6 to 11 swellings per year.
HAE-related swelling is non-whealing and non-pruritic with ill defined margins, and generally remains unrelieved by antihistamines and corticosteroids. About 25 percent of Hereditary Angioedema (HAE) patients experience a non-pruritic erythematous rash that often occurs during the attack prodrome.
Swelling involving the feet and hands is extremely uncomfortable, and often prevents patients from being able to participate in normal daily routines. Gastrointestinal attacks produce excruciating abdominal pain, nausea, vomiting, and diarrhea caused by swelling in the intestinal wall. This symptom is a distinguishing feature of Hereditary Angioedema (HAE) because abdominal pain is rarely seen in other types of angioedema. Hypovolemia can occur from a combination of fluid loss, plasma extravasation, and vasodilation, and can progress into hypovolemic shock.
Approximately one third of patients with undiagnosed Hereditary Angioedema (HAE) undergo unnecessary surgery during abdominal attacks because the symptoms mimic a surgical emergency.
Laryngeal edema is the most significant feature of HAE, because swelling can close the airway and cause death by asphyxiation. Studies of Hereditary Angioedema (HAE) families indicate that death from laryngeal edema can be as high as 30 percent of those affected by the disease. Surveys of Hereditary Angioedema (HAE) patients reveal that approximately 50 percent experienced at least one laryngeal episode in their lives.A study by German investigators that focused exclusively on airway attacks in 123 patients revealed that nearly 80% of the laryngeal edemas occurred between the ages of 11 and 45 years, and the mean interval between onset and maximum development of laryngeal edema was 8.3 hours. Nevertheless, laryngeal edema must be treated as a medical emergency, and patients should to seek prompt treatment as soon as throat involvement is suspected.