Investigation into the α-Gal syndrome: Characteristics of 261 children and adults reporting red meat allergy.

BACKGROUND: Red meat allergy has historically been understood as a rare disease of atopic children, but the discovery of the "alpha-Gal syndrome," which relates to IgE to the oligosaccharide galactose-alpha-1,3-galactose (alpha-Gal), has challenged that notion. OBJECTIVE: To describe the clinical and immunologic characteristics of a large group of subjects with self-reported allergy to mammalian meat. METHODS: This was an observational study of 261 children and adults (range, 5-82 years) who presented for evaluation for allergic reactions to mammalian meat. Results were based on serum assays and a detailed questionnaire. RESULTS: alpha-Gal specific IgE >= 0.35 IU/mL was detected in 245 subjects and symptom onset occurred >= 2 hours after eating mammalian meat in 211 (81%). Component testing supported a diagnosis of alpha-Gal syndrome in 95%, pork-cat syndrome in 1.9%, and primary beef allergy in 1.1%. Urticaria was reported by 93%, anaphylaxis by 60%, and gastrointestinal symptoms by 64%. Levels of IgE and IgG specific to alpha-Gal were similar in subjects who reported early-or delayed-onset symptoms, and in those with and without anaphylaxis. Levels of alpha-Gal specific IgE and severity of reactions were similar among those with and without traditional atopy, and among children (n = 35) and adults (n = 226). Blood group B trended toward being under-represented among alpha-Gal-sensitized subjects; however, alpha-Gal specific IgE titers were high in symptomatic cases with B-antigen. CONCLUSIONS: The alpha-Gal syndrome is a regionally common form of food allergy that has a characteristic but not universal delay in symptom onset, includes gastrointestinal symptoms, can develop at any time in life, and is equally common in otherwise nonatopic individuals. (C) 2019 Published by Elsevier Inc. on behalf of the American Academy of Allergy, Asthma & Immunology