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Clinical Presentation and Outcomes of Alpha-Gal Syndrome
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- This single-center retrospective cohort study assessed the clinical presentation and outcomes of patients with Alpha-Gal syndrome. Clinical characteristics and outcomes of seropositive patients (n = 124) were compared with those of age- and sex-matched seronegative patients (n = 380). Seropositive patients had a 26-fold greater frequency of tick bites than seronegative patients and had a higher prevalence of urticaria. Interestingly, seropositive patients had a lower prevalence of heartburn and bloating and were less likely to have asthma. Dietary restrictions resulted in complete symptom resolution in 55% of the patients.
- Alpha-Gal syndrome should be considered in individuals with a history of tick exposure and allergic and/or gastrointestinal symptoms. Dietary restriction is effective in many but not all patients.
abstract
This abstract is available on the publisher's site.
Access this abstract now Full Text Available for ClinicalKey SubscribersBACKGROUND AND AIMS
Alpha-Gal Syndrome (AGS) is an IgE-mediated allergic reaction to galactose-α-1,3-galactose, primarily linked with lone star tick bites in the US. It presents with symptoms ranging from urticaria and gastrointestinal (GI) manifestations to delayed anaphylaxis following red meat consumption. We aimed to study AGS patients' clinical manifestations, diagnosis, and outcomes.
METHODS
A retrospective chart review of patients who underwent serological testing for suspected AGS between 2014-2023 at Mayo Clinic was performed. Patients with positive serology were age and sex-matched with those who tested negative. Clinical characteristics of seropositive cohort with and without GI symptoms were compared, and outcomes assessed.
RESULTS
Of 1260 patients who underwent testing, 124 tested positive for AGS. They were matched with 380 seronegative controls. AGS patients reported a higher frequency of tick bites (OR 26.0 [95% CI 9.8-68.3]), prevalence of urticaria (56 % vs. 37%; P=.0008) and were less likely to have asthma (OR 0.4 [0.3 to 0.7]). They had a lower prevalence of heartburn (6% vs. 12%; P=.03) and bloating (6% vs. 13%; P=.03). 47% had GI symptoms and higher proportion were female than those without GI symptoms (69% vs. 35%; P=.002). During a mean follow up of 27 months, 22 of 40 patients reported symptom resolution after avoiding red meat, and 7 were able to transition to regular diet.
CONCLUSION
A diagnosis of AGS should be strongly considered in patients with a history of tick bites and clinical presentation of allergic or GI manifestations. Dietary intervention is effective in most but not all patients.
Additional Info
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Clinical Presentation and Outcomes of Alpha-Gal Syndrome
Clin. Gastroenterol. Hepatol. 2024 Jul 25;[EPub Ahead of Print], E Lesmana, S Rao, A Keehn, AL Edwinson, A Makol, M GroverFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
The diagnosis of alpha-gal syndrome (AGS) can be challenging, and the clinical outcomes of patients with AGS have not been well-studied. This key contribution by Lesmana and colleagues is a retrospective cohort study of patients who underwent serological testing for suspected AGS between 2014 and 2023 at the Mayo Clinic. The investigators sought to further delineate the clinical presentation and outcomes of AGS. Overall, approximately 10% of the patients tested positive for alpha-gal serologies using an IgE threshold of 0.35 IU/mL. Approximately half of these patients had gastrointestinal (GI) symptoms. Compared with seronegative individuals, those with AGS experienced urticaria more often and were more likely to have a history of a tick bite. They were less likely to have heartburn, bloating, or a history of asthma. Higher serological titers were correlated with a history of a tick bite and urticaria, as well as a longer time to symptom onset. Those with AGS and GI symptoms were more likely to be female. In terms of outcomes, 55% of the patients with AGS reported symptom resolution following a red meat–free diet and avoidance of tick exposure.
These findings give rise to several considerations. Given the difficulty of identifying potential AGS in patients based on clinical symptoms, perhaps increasing the rate of alpha-gal IgE testing, especially in those with GI symptoms and urticaria or those with difficult-to-control GI symptoms of unclear etiology, would be beneficial. However, as the investigators point out, increased rates of testing, especially using a lower testing threshold of 0.1 IU/mL utilized in other recent studies, may serve primarily to increase false-positive rates. As with any other food-allergy testing, this could pose significant hardship to patients who may be advised to implement unnecessary dietary restrictions. In addition, more studies are needed to establish whether higher serologic titers are correlated with delayed time to symptom onset. The mechanism remains unclear, and this has not been consistent with other studies. Furthermore, the natural history of AGS remains elusive. As the investigators point out, the effect of dietary restriction (vs tick avoidance, for instance) on symptom resolution has not been well-established, as well as the type of dietary restriction (ie, red meat, dairy, etc) and the duration that may be most effective. Following alpha-gal IgE levels over time may be beneficial given that some participants transitioned to normal serology and were able to reintroduce red meat into their diet.