Clinical presentation and outcomes of Alpha-Gal syndrome (AGS)
Lesmana E et al, Clin Gastroenterol Hepatol. 2025;23(1):69-78
The alpha-gal syndrome is an IgE-mediated allergic reaction to galactose-α-1,3 galactose linked to Lone Star tick bites in the United States that presents with urticaria, gastrointestinal symptoms and delayed anaphylaxis following red meat consumption. It has been proposed that European ticks might cause similar complaints. This American cohort study of AGS patients suggests that a diagnosis of AGS should be considered in patients with a history of tick bites and allergic or gastrointestinal manifestations. Most patients responded to a diet avoiding red meat.
Background 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 United States. It presents with symptoms ranging from urticaria and gastrointestinal (GI) manifestations to delayed anaphylaxis following red meat consumption. The authors 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 and 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 control subjects. AGS patients reported a higher frequency of tick bites (odds ratio [OR] = 26.0; 95% confidence interval [CI]: 9.8–68.3), reported a higher prevalence of urticaria (56% vs. 37%; p = 0.0008), and were less likely to have asthma (OR = 0.4; 95% CI: 0.3–0.7). They had a lower prevalence of heartburn (6% vs. 12%; p = 0.03) and bloating (6% vs. 13%; p = 0.03). A total of 47% had GI symptoms, and a higher proportion were female than those without GI symptoms (69% vs. 35%; p = 0.002). 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.
Conclusions: A diagnosis of alpha-gal syndrome should be strongly considered in patients with a history of tick bites and clinical presentation of allergic or gastrointestinal manifestations. Dietary intervention is effective in most but not all patients.