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Research Letter
November 21, 2018

α-Gal Syndrome vs Chronic Urticaria

Author Affiliations
  • 1Department of Dermatology, University of Virginia, Charlottesville
  • 2Department of Medicine, University of Virginia, Charottesville
  • 3Department of Microbiology, University of Virginia, Charottesville
  • 4Division of Rheumatology, Allergy & Immunology, The University of North Carolina at Chapel Hill, Chapel Hill
JAMA Dermatol. Published online November 21, 2018. doi:10.1001/jamadermatol.2018.3970

Galactose-α-1,3-galactose (α-gal) is an oligosaccharide expressed on glycoproteins and glycolipids of nonprimate mammals and is the causal epitope of an IgE-mediated allergy to mammalian meat.1,2 First reported in 2009, the α-gal syndrome is an increasingly appreciated problem across the southeastern United States and other parts of the world.2 It is clear that tick bites, specifically relating to Amblyomma americanum (lone star tick), are causal in many, if not most, cases of α-gal sensitization in the United States.3 Following sensitization, many individuals will experience allergic symptoms on ingestion of meat or other products (eg, dairy) derived from nonprimate mammals. In contrast to typical IgE-mediated reactions, which occur within minutes of exposure, the α-gal allergy typically has a delayed onset of 2 to 6 hours.2 The severity of the reaction varies from general urticaria to anaphylaxis, and individuals may not react to every exposure. Because of these atypical features, proper diagnosis can prove challenging. An epidemiological investigation of a pediatric population reported that α-gal may be misdiagnosed as recurrent urticaria or idiopathic anaphylaxis.4 While a recent report postulated that α-gal syndrome might represent a novel cause of chronic urticaria, further research failed to find such an association.5,6 Nevertheless, in areas where α-gal sensitization is prevalent, the potential for misdiagnosing cases of α-gal syndrome as chronic urticaria still exists. Here, we report cases labeled as chronic urticaria or chronic idiopathic urticaria within a cohort of patients in central Virginia being evaluated for α-gal syndrome.

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