Knowledge Check
Which of the following statements about Alpha-gal Syndrome (AGS) is true based on recent findings?
- Alpha-gal Syndrome is primarily caused by exposure to certain types of seafood.
- Most patients with AGS do not experience any gastrointestinal symptoms.
- Avoidance of red meat is an effective management strategy for reducing AGS symptoms.
- Alpha-gal Syndrome is equally prevalent in males and females.
Alpha-Gal Syndrome: An Actual GI Ache
Vanessa M. Shami, MD, FASGE, reviewing Lesmana E, et al. Clin Gastroenterol Hepatol 2024 Jul 25.
The prevalence of Alpha-gal Syndrome (AGS) is increasing. This condition involves an IgE-mediated allergic reaction to galactose-α-1,3-galactose and its derivatives, with the lone star tick in the U.S. being a primary vector. Symptoms include urticaria, anaphylaxis, and GI symptoms, including nausea, vomiting, abdominal pain, and bloating following red meat consumption. A recent retrospective cohort study aimed to study clinical manifestations, diagnosis, and outcomes of AGS.
A chart review conducted at Mayo Clinic identified patients who underwent serological testing for suspected AGS between 2014 and 2023. Of 1260 patients tested, 124 were positive for AGS. These patients were age- and sex-matched with 380 seronegative individuals.
Patients with AGS were more likely than controls to have a history of tick bites (odds ratio [OR], 26.0; 95% confidence interval, 9.8-68.3) and to experience urticaria (56% vs 37%; P = .0008). Of the patients with AGS, 47% had at least one GI symptom, with the most common being diarrhea (32.3%), nausea (31.4%), vomiting (22.6%), and abdominal pain (21.8%). A higher proportion of patients with GI symptoms were female than those without GI symptoms (69% vs 35%; P = .002). Over a mean follow-up of 27 months with 40 patients, 22 reported symptom resolution and 14 noted a decrease in symptom severity after avoiding red meat. Seven patients were able to resume a regular diet.
COMMENT
Clinicians should consider AGS as a diagnosis when patients present with gastrointestinal symptoms, especially in areas where the lone star tick is prevalent. Testing for alpha-gal IgE is advisable for patients with tick exposure and symptoms, as dietary changes may significantly alleviate their symptoms.
Note to readers: At the time we reviewed this paper, its publisher noted that it was not in final form and that subsequent changes might be made.
Vanessa M. Shami, MD, FASGE
CITATION
Lesmana E, Rao S, Keehn A, Edwinson AL, Makol A, Grover M. Clinical presentation and outcomes of Alpha-gal Syndrome. Clin Gastroenterol Hepatol 2024 Jul 25. (Epub ahead of print) (https://doi.org/10.1016/j.cgh.2024.06.044)
COMMENT
This study affirms important principles for FIT screening. First, cancers detected by FIT remain in an early stage during subsequent screening rounds. Further, increasing the cutoff level of hemoglobin for positive test results reduces sensitivity but does not shift the fraction of detected cancers substantially toward later-stage CRC. Thus, programs can adjust the cutoff to levels appropriate for their colonoscopy resources, and the detected cancers will be in an early stage across a range of hemoglobin thresholds for positive tests.