Alpha - Gal Syndrome

Last edited 11/2023 and last reviewed 11/2023

Alpha-Gal Syndrome

Alpha-gal syndrome (AGS) is an unconventional food allergy, characterized by IgE-mediated hypersensitivity responses to the glycan galactose-alpha-1,3-galactose (alpha-gal) and not to a food-protein

• also known as alpha-gal allergy, red meat allergy, or mammalian meat allergy (MMA),
• is characterized by the generation of immune-mediated hypersensitivity responses to the carbohydrate galactose-alpha-1,3-galactose (alpha-gal)
  • alpha-gal moieties are common in nature and present in non-primate mammals such as cows, pigs, and sheep
  • are also present in various food products derived from those animals including dairy products, meat, and their innards
  • consumption of those food products may result in symptoms ranging from urticaria to potentially lethal anaphylaxis
  • AGS has many novel features that broaden the paradigm of food allergy, including that reactions are delayed 3-6 hours after exposure and patients have frequently tolerated red meat for many years prior to the development of allergic reactions (2)
  • individuals suffering from AGS may also be exposed to alpha-gal through various pharmaceutical products that contain alpha-gal such as the cancer drug cetuximab
• development of alpha-gal IgE is associated with tick bites though the possibility of other parasites promoting sensitization to alpha-gal remains (1)
• in >90% of cases the diagnosis of AGS can be made based on a history of delayed allergic reactions after eating non-primate mammalian meat (e.g., "red meat" such as beef, pork, or lamb) and a positive blood test (>0.1 IU/mL) for IgE to alpha-gal (2)
• is no cure for AGS
  • mainstay of AGS management is to recommend avoidance of the allergen

Reference:

• Macdougall JD, Thomas KO, Iweala OI. The Meat of the Matter: Understanding and Managing Alpha-Gal Syndrome. Immunotargets Ther. 2022 Sep 15;11:37-54. doi: 10.2147/ITT.S276872. PMID: 36134173; PMCID: PMC9484563.
• Commins SP. Diagnosis & management of alpha-gal syndrome: lessons from 2,500 patients. Expert Rev Clin Immunol. 2020 Jul;16(7):667-677. doi: 10.1080/1744666X.2020.1782745. Epub 2020 Jul 8. PMID: 32571129; PMCID: PMC8344025