alpha-gal syndrome
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Etiology
Epidemiology
- see lone star tick
- suspected cases predominantly occurred in counties within the southern, midwestern, & mid-Atlantic U.S.[2]
- patients with alpha-gal syndrome report a higher frequency of tick bites (RR=26)[5]
Pathology
- developmennt of allergy to galactose-alpha-1,3-galactose (alpha-gal)
- tick saliva may contain alpha-gal obtained from other mammals on which the tick has fed
- exposure to alpha-gal containing tick saliva then triggers development of alpha-gal specific IgE antibodies in humans
- once sensitized, consumption of red meat triggers hypersensitivity
Clinical manifestations
- most common:
- pruritus or urticaria (70%)
- gastrointestinal symptoms (40%), more females 69% than males 35%[5]
- angioedema
- contact urticaria of the oral mucosa
- anaphylaxis
- other
- symptoms are delayed in onset, often 3-6 hours after eating*
- patients have awakened from sleep with allergic symptoms or anaphylaxis after eating red meat for dinner
- symptoms occur after meat consumption[5]
* carbohydrate alpha-gal is bound to lipid
* lipids are absorbed into the gut and circulation more slowly than proteins
Laboratory
- alpha-gal IgE in serum/plasma >= 0.1 IU/mL (confirmatory)
- serum tryptase may be elevated during acute episode
- baseline serum trypase is normal
Differential diagnosis
- systemic mastocytosis
- serum tryptase > 20 ng/mL (< 11.4 ng/mL is normal)
- often elevated at baseline as well as during an episode[6]
- serum tryptase > 20 ng/mL (< 11.4 ng/mL is normal)
Management
- supportive care
- no treatment of cure available[3]
More general terms
Additional terms
References
- ↑ Rothaus C Hunting for a Diagnosis NEJM Resident 360. Feb 3, 2021 https://resident360.nejm.org/clinical-pearls/hunting-for-a-diagnosis
- ↑ Jump up to: 2.0 2.1 Thompson JM, Carpenter A, Kersh GJ, Wachs T, Commins SP, Salzer JS. Geographic Distribution of Suspected Alpha-gal Syndrome Cases - United States, January 2017-December 2022. MMWR Morb Mortal Wkly Rep 2023;72:815-820. Jyly 28. PMID: https://www.ncbi.nlm.nih.gov/pubmed/37498787 https://www.cdc.gov/mmwr/volumes/72/wr/mm7230a2.htm
- ↑ Jump up to: 3.0 3.1 Carpenter A, Drexler NA, McCormick DW, et al. Health Care Provider Knowledge Regarding Alpha-gal Syndrome - United States, March-May 2022. MMWR Morb Mortal Wkly Rep 2023;72:809-814. July 28 PMID: https://www.ncbi.nlm.nih.gov/pubmed/37498792 https://www.cdc.gov/mmwr/volumes/72/wr/mm7230a1.htm
- ↑ Centers for Disease Control & Prevention (CDC) Alpha-gal Syndrome (AGS) 2022 Case Definition https://ndc.services.cdc.gov/case-definitions/alpha-gal-syndrome-ags/
- ↑ Jump up to: 5.0 5.1 5.2 5.3 5.4 Lesmana E, Rao S, Keehn A, Edwinson AL, Makol A, Grover M. Clinical Presentation and Outcomes of Alpha-Gal Syndrome. Clin Gastroenterol Hepatol. 2025 Jan;23(1):69-78. PMID: https://www.ncbi.nlm.nih.gov/pubmed/39067555 https://www.cghjournal.org/article/S1542-3565(24)00672-4/fulltext
- ↑ Jump up to: 6.0 6.1 Medical Knowledge Self Assessment Program (MKSAP) 20 American College of Physicians, Philadelphia 2025