Man’s Only Symptom of HAE Type 2 Is Abdominal Pain: Case Report

Imaging studies during asymptomatic periods showed no abnormalities

Jacob Harney, PhD avatar

by Jacob Harney, PhD |

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An image of the human digestive system.

Researchers have reported the case of a 19-year-old man whose only symptom of hereditary angioedema (HAE) was abdominal pain.

His diagnosis relied on laboratory tests, which revealed normal levels, but low activity, of the C1 inhibitor protein (C1-INH) — a telltale sign of HAE type 2.

The man’s case was detailed in the study, “Recurrent abdominal pain as the only clinical manifestation of hereditary angioedema type II,” that was published as a letter to the editor in The Spanish Journal of Gastroenterology.

Angioedema is typically identified by swelling. Often, this is restricted to the skin, but it can also occur in the membranes that line the respiratory and gastrointestinal tract, leading to breathing difficulties for the former and vomiting or abdominal pain for the latter.

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Symptoms of HAE Can Occur Without Swelling Attack: Study

HAE type 1 and 2 are caused by mutations in the SERPING1 gene that carries instructions for making C1-INH. While in type 1, C1-INH levels are low, in type 2 protein levels are normal or elevated, but its activity is reduced.

The end result with both is the overproduction of an inflammatory protein called bradykinin that drives swelling attacks. Patients also often have abnormally low levels of the complement 4 protein, or C4.

Researchers in Spain described the case of a 19-year-old man who was seen in their clinic for recurrent bouts of abdominal pain over the previous three years.

He had no notable family disease history and didn’t have any other HAE symptoms. He reported no weight loss, gastrointestinal bleeding, skin lesions, eye problems, mouth ulcers, or muscular pain associated with a joint. His physical exam was normal.

A CT scan and ultrasound performed during a symptomatic period revealed a thickening of the lining of the digestive tract, signs of inflammation, and fluid accumulation in his abdomen.

These findings suggested jejunitis, ileitis, and colitis, which refer to inflammation of various parts of the digestive tract. But lab tests based on blood and feces samples, as well as examinations of the inside of the stomach, esophagus, and colon, found no notable alterations, and no abnormalities were seen in imaging studies conducted during asymptomatic periods.

The patient was hospitalized again in 2022 due to a new pain episode and a CT scan continued showing signs of inflammation in the digestive tract. It was then revealed that all his pain episodes occurred after a viral infection, namely COVID-19, flu, and a rhinovirus infection.

Lab tests showed he had low levels of C4 and elevated levels of C1-INH. The activity of C1-INH was low, however, at 8% compared with a normal range, which usually varies from 70–130%. The man was diagnosed with HAE type 2 and referred to an allergist who prescribed a C1 esterase inhibitor if new episodes occurred.

“Because of its low incidence, the heterogeneous and transitional clinical features and, sometimes, no family medical history, misdiagnosis or late diagnosis are common in clinical practice,” the researchers wrote. “It is necessary to rule out HAE by quantifying C4 levels and if they are low, request activity and levels of C1- INH, in patients with inexplicable recurrent abdominal pain, even in absence of cutaneous [skin] manifestations, since a specific treatment could be administered, and unnecessary examinations avoided.”