The timely diagnosis of hereditary angioedema (HAE) could be even more challenging in the presence of other pathologic entities, according to a study recently published in Annals of Allergy, Asthma & Immunology.

“The recurrent abdominal pain caused by intestinal swelling due to HAE [has] caused patients to undergo emergent abdominal surgeries including appendectomies, cholecystectomies, and hysterectomies before the correct diagnosis is ever established,” the authors wrote.

This case report describes a 61-year-old man previously diagnosed with Prader-Willi syndrome (PWS) who presented with abdominal pain after a car accident. Further questioning revealed a previous episode of upper limb swelling that lasted for 1 week until spontaneous resolution and another car accident 1 month prior that led to abdominal and lower limb swelling.

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Regarding family history, 5 family members had a type 1 HAE diagnosis, including the patient’s mother, sister, brother, maternal grandmother, and niece.

Read more about HAE epidemiology

The healthcare team obtained complement protein values during an asymptomatic period, observing normal C4 and C1q levels. C1 esterase inhibitor level and function were both mildly decreased at 20 mg/dL and 50%, respectively.

Genetic tests demonstrated a heterozygous SERPING1 mutation. This finding confirmed a diagnosis of HAE. However, despite having a family history of type 1 HAE, this patient had the type 2 form of the disease. He initiated treatment with icatibant, administered subcutaneously upon demand, as rescue therapy.

This article highlights the importance of addressing all symptoms in each patient, regardless of any underlying conditions. Many factors probably intervened in the delayed diagnosis of this case. For example, since this patient was residing in a special center for individuals with PWS, it is possible the frequent episodes of abdominal pain were ruled out as common occurrences attributable to his underlying disease and hence were never fully studied.

Furthermore, patients with PWS often have increased pain tolerance, while the cognitive impairment that is often present hinders proper communication of any symptoms the individual may be experiencing.

“Early diagnosis is crucial in the prevention of these extreme and unnecessary treatments, but also in preventing mortality and morbidity associated with pain,” the authors concluded.


Jalil M, Hostoffer Z, Callahan M, Hostoffer R. Delayed diagnosis of hereditary angioedema in the setting of Prader Willi syndrome. Ann Allergy Asthma Immunol. Published online August 14, 2022. doi:10.1016/j.anai.2022.08.005