Walter Reed National Military Medical Center Bethesda, MD
Award: Presidential Poster Award
Brianna Bahe, MD, Andrew Mertz, MD, Patrick Young, MD, FACG Walter Reed National Military Medical Center, Bethesda, MD
Introduction: Alpha-gal syndrome (AGS) is a rare, acquired allergic reaction to mammalian meat that most commonly develops in the United States following tick exposure. The arthropod bite leads to formation of a specific IgE antibody to oligosaccharide galactose-α-1,3-galactose (alpha-gal). Patients with AGS classically present with a myriad of symptoms that can range in severity from localized pruritis to anaphylaxis. There are however a subset of patients with AGS that only present with gastrointestinal symptoms, which can present a unique diagnostic challenge. Herein, we describe a classic case of AGS in a patient with markedly elevated alpha-gal IgE levels at diagnosis that normalized following strict dietary modification.
Case Description/Methods: A 78-year-old man initially presented to the GI clinic for evaluation of a 6-month history of episodic vomiting and diarrhea occurring almost exclusively late in the evening. Symptoms would typically manifest as abrupt onset of vomiting with watery diarrhea and overwhelming malaise. Notably, he denied any history of chronic GI complaints prior to this onset. No trigger foods were initially identified and his hematologic, blood chemistry, and infectious lab evaluations were unrevealing. He then started to experience a concomitant urticarial eruption, which, in conjunction with new historical data regarding a particular tick bite exposure several months prior to symptom onset, prompted evaluation for AGS. Serologic assessment revealed significantly elevated alpha-gal IgE, which comprised a significant quantity of total serum IgE. The patient ultimately received a diagnosis of AGS and, following avoidance of beef, dairy, and gelatin-containing products, experienced normalization of both symptoms and alpha-gal IgE within one month.
Discussion: The mechanism behind the pathogenesis of AGS remains poorly understood. The clinical presentation, on the other hand, has become a more widely recognized syndrome. This patient displayed the classic gastrointestinal, dermatologic, and likely cardiovascular symptoms that are seen in AGS. This syndrome is distinct from other food allergy syndromes in that the driving allergen is a carbohydrate, of which the absorption is delayed to several hours following food exposure. This classic 3-6 hour delay from time of food exposure to onset of symptoms is the hallmark feature that makes AGS distinct from other anti-protein epitope IgE mediated allergic reactions and makes diagnosis so elusive.
Disclosures:
Brianna Bahe indicated no relevant financial relationships.
Andrew Mertz indicated no relevant financial relationships.
Patrick Young indicated no relevant financial relationships.
Brianna Bahe, MD, Andrew Mertz, MD, Patrick Young, MD, FACG. E0120 - A Diagnosis Rarer Than My Steak: The Challenges Behind Alpha-Gal Syndrome, ACG 2022 Annual Scientific Meeting Abstracts. Charlotte, NC: American College of Gastroenterology.
