The study will include all participants with angioedema and participants with previous episodes of abdominal pain of no obvious aetiology.

Hereditary Angioedema Disease (HAE) is a rare inherited disorder characterised by recurrent episodes of the accumulation of fluids outside of the blood vessels, blocking the normal flow of blood or lymphatic fluid and causing rapid swelling of tissues in the hands, feet, limbs, face, intestinal tract, or airway.

The diagnosis is complicated because HAE is extremely rare and most physicians typically never see a patient with the disorder. In addition, most cases of angioedema are caused by an allergic reaction.

Gastrointestinal, abdominal tract involvement is an important feature and one of the most common in HAE.  Abdominal attacks may be mistaken for conditions such as appendicitis, cholecystitis, pancreatitis and ischemic bowel. Often, patients can be misdiagnosed as having psychosomatic symptoms and are inappropriately referred for psychiatric evaluation.

The difficulty in recognizing gastrointestinal symptoms as being related to HAE often leads to a delay in diagnosis and to unnecessary surgical procedures.  .

The detection of HAE through blood sampling will permit early diagnosis and disease activity and progression to be assessed at an early stage and thus ultimately permit better treatment.