New research published in Swiss Medical Weekly calls attention to the role of hereditary alpha-tryptasemia (HAT) in exacerbating anaphylaxis risk among individuals with mast cell disorders, including systemic mastocytosis (SM).
HAT is a genetic trait that affects 4% to 6% of the general population and is characterized by an excess of the TPSAB1 gene, which leads to elevated levels of a protein called alpha tryptase. Excess alpha tryptase is linked to a higher risk of severe allergic reactions, including anaphylaxis. The prevalence of HAT is higher in people with SM, and researchers say the combination of both disorders can increase the sensitivity to triggers like wasp and bee stings.
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To highlight this point, the review’s authors highlighted the case of a 53-year-old man with a history of severe anaphylactic reactions following insect stings. His symptoms included rapid onset of shortness of breath, nausea and vomiting, drowsiness, low blood pressure and paresthesias (feeling “pins and needles”). A diagnostic workup revealed the man had SM, and further genetic testing showed multiple copies of the TPSAB1 gene, signalling HAT. Doctors diagnosed the man with both conditions, which they say exacerbated his risk of severe anaphylaxis. They treated him with an H1-blocker and venom immunotherapy, which they doubled the dose of following another anaphylactic reaction after a bee sting.
The researchers say the case illustrates how genetic testing for HAT could be a useful tool for individuals with mast cell disorders.
“The prevalence of hereditary alpha-tryptasemia is increased in patients with systemic mastocytosis, and these patients are at high risk of severe mast cell mediator symptoms and anaphylaxis,” they wrote. “Therefore, it is crucial in the diagnostic workup to screen for both hereditary alpha-tryptasemia and systemic mastocytosis in patients with anaphylactic reactions or symptoms of mast cell mediator release.”
The authors note that identifying HAT in people with SM could provide doctors with critical information for more precise management and the creation of individualized, symptom-based treatment plans. They also recommend that first-degree relatives with anaphylactic reactions or symptoms of mast cell mediator release be tested for HAT, as identifying the genetic trait early could help improve monitoring and intervention before a severe reaction occurs.
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