Recurrent abdominal attacks as a presentation of hereditary angioedema type I: a multigenerational family series

We present a Mexican multigenerational family series of type I hereditary angioedema (HAE) with predominant abdominal involvement, including three affected adult sisters and a child identified through family screening. The index case was a 44-year-old woman with recurrent abdominal attacks, chronic diarrhea, multiple hospitalizations, and previous abdominopelvic interventions with no conclusive findings. During her clinical course, she developed non-urticarial lip edema, and abdominal CT showed segmental thickening of jejunal loops and mesenteric edema, findings consistent with bowel wall edema during an abdominal attack. The diagnosis was confirmed by low C4, decreased C1-INH functional activity, and low C1-INH antigenic levels. Family evaluation identified additional cases compatible with type I HAE, supporting a pattern of vertical transmission. After diagnosis, the index case received on-demand icatibant and initiated long-term prophylaxis with lanadelumab, remaining asymptomatic at the most recent follow-up. This series highlights the importance of considering HAE in patients with unexplained recurrent abdominal pain, edema without urticaria, and a suggestive family history, particularly when imaging suggests reversible small-bowel involvement, in order to reduce diagnostic delay and prevent potentially avoidable interventions.