20.500.12556/DiRROS-29284 Markedly increased diamine oxidase during acute anaphylaxis is associated with an underlying clonal mast cell disorder Introduction Diamine oxidase (DAO) degrades histamine, the key mediator in anaphylaxis, yet its relationship with clonal mast cell disorder (CMD) in the context of anaphylaxis is unclear. We evaluated whether DAO during anaphylaxis differs by CMD status. Methods We enrolled 35 emergency-department patients with acute anaphylaxis to drugs (7 patients), food (2 patients), or Hymenoptera venom (26 patients). Tryptase, DAO, and histamine degradation were measured during anaphylaxis and convalescence. CMD was defined by detecting KIT p.D816V in peripheral blood leukocytes using highly sensitive qPCR. Post-mortem DAO and tryptase were also compared in two fatal Hymenoptera venom-triggered anaphylaxis (HVA) cases with CMD versus 13 non-anaphylaxis controls. Results KIT p.D816V was detected in 6 (17%); all had severe HVA and normal basal tryptase. During anaphylaxis, DAO increased markedly in CMD (median 1142%), but only modestly in KIT p.D816V-negative patients (median 20%; p < 0.0001), independent of trigger or severity. Acute DAO was ~5-fold higher in CMD (median 101 vs. 18 U/mL), while convalescent DAO was similar (both 14 U/mL). Despite markedly elevated DAO, we observed impaired histamine degradation in acute anaphylaxis plasma. Receiver-operating-characteristic analyses showed strong discrimination for CMD using acute DAO (AUC 0.92; cut-off 53 U/mL; sensitivity 83%; specificity 97%) and percentage increase from convalescence (AUC 0.97; cut-off 223%; sensitivity 83%; specificity 100%). Post-mortem DAO lacked specificity, whereas post-mortem tryptase supported the diagnosis of fatal anaphylaxis and CMD. Conclusion DAO concentrations rise markedly during anaphylaxis in CMD and may help identify individuals at the highest risk. Further studies should refine the diagnostic utility and elucidate the mechanisms by which DAO may amplify anaphylaxis in CMD. anaphylaxis clonal mast cell disorder diamine oxidase KIT p.D816V tryptase anafilaksija klonalna motnja mastocitov diamin oksidaza DAO KIT p.D816V triptaza true false true Blackwell Science, 1997- Clinical & experimental allergy Angleški jezik Slovenski jezik "© 2026 The Author(s). Clinical & Experimental Allergy published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited." Neznano 2026-05-06 10:46:05 2026-05-06 10:46:05 2026-05-07 03:51:12 0000-00-00 00:00:00 2026 0 0 Nasl. z nasl. zaslona; Opis vira z dne 5. 5. 2026; str. 516-525 issue 5 Vol. 56 2026 0000-00-00 Zaloznikova Objavljeno NiDoloceno 2025-10-30 2026-01-23 2026-01-29 616-008.61 1365-2222 10.1111/cea.70227 266808579 https://onlinelibrary.wiley.com/doi/full/10.1111/cea.70227 1 059f2380-4928-11f1-8a5a-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=43832 RAZ_Rijavec_Matija_2026.pdf RAZ_Rijavec_Matija_2026.pdf 1 99285E4DAF2B19C3403BF386F9D3ED20 4df399d15522aa7d7dfdc22773e1ee49c5c80e4c6e4bdf781b5f2fcea020ca0d a2d7c24f-4929-11f1-8a5a-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=43835 Univerzitetna klinika za pljučne bolezni in alergijo Golnik 0 0 0