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Query: "keywords" (hereditary alpha-tryptasemia) .

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1.
Heritable risk for severe anaphylaxis associated with increased [alpha]-tryptase-encoding germline copy number at TPSAB1
Jonathan J. Lyons, Jack Chovanec, Michael P. O'Connell, Yihui Liu, Julij Šelb, Roberta Zanotti, Yun Bai, Jiwon Kim, Quang T. Le, Tom DiMaggio, Matija Rijavec, Peter Korošec, 2020

Abstract: Background: An elevated basal serum tryptase level is associated with severe systemic anaphylaxis, most notably caused by Hymenoptera envenomation. Although clonal mast cell disease is the culprit in some individuals, it does not fully explain this clinical association. Objective: Our aim was to determine the prevalence and associated impact of tryptase genotypes on anaphylaxis in humans. Methods: Cohorts with systemic mastocytosis (SM) and venom as well as idiopathic anaphylaxis from referral centers in Italy, Slovenia, and the United States, underwent tryptase genotyping by droplet digital PCR. Associated anaphylaxis severity (Mueller scale) was subsequently examined. Healthy volunteers and controls with nonatopic disease were recruited and tryptase was genotyped by droplet digital PCR and in silico analysis of genome sequence, respectively. The effects of pooled and recombinant human tryptases, protease activated receptor 2 agonist and antagonist peptides, and a tryptase-neutralizing mAb on human umbilical vein endothelial cell permeability were assayed using a Transwell system. Results: Hereditary [alpha]-tryptasemia (H[alpha]T)--a genetic trait caused by increased [alpha]-tryptase-encoding Tryptase-[alpha]/[beta]1 (TPSAB1) copy number resulting in elevated BST level--was common in healthy individuals (5.6% [n = 7 of 125]) and controls with nonatopic disease (5.3% [n = 21 of 398]). H[alpha]T was associated with grade IV venom anaphylaxis (relative risk = 2.0; P < .05) and more prevalent in both idiopathic anaphylaxis (n = 8 of 47; [17%; P = .006]) and SM (n = 10 of 82 [12.2%; P = .03]) relative to the controls. Among patients with SM, concomitant H[alpha]T was associated with increased risk for systemic anaphylaxis (relative risk = 9.5; P = .007). In vitro, protease-activated receptor-2-dependent vascular permeability was induced by pooled mature tryptases but not [alpha]- or [beta]-tryptase homotetramers. Conclusions: Risk for severe anaphylaxis in humans is associated with inherited differences in [alpha]-tryptase-encoding copies at TPSAB1.
Keywords: mastocytosis, venoms, hypersensitivity, anaphylaxis - diagnosis, mast cells, idiopathic anaphylaxis, mast cell activation, hereditary alpha-tryptasemia
DiRROS - Published: 11.09.2020; Views: 468; Downloads: 63

2.
Routine KIT p.D816V screening identifies clonal mast cell disease in Hymenoptera allergic patients regularly missed using baseline tryptase levels alone
Peter Korošec, Jonathan J. Lyons, Mitja Košnik, Samo Zver, Vladka Čurin-Šerbec, Yihui Liu, Young Hwan Park, Ajda Demšar, Nisera Bajrović, Matevž Škerget, Peter Kopač, Mihaela Zidarn, Renato Eržen, Matija Rijavec, Julij Šelb, 2021

Abstract: Background. Clonal mast cell disorders and elevated BST of unknown cause(s) are associated with severe Hymenoptera venom-triggered anaphylaxis (HVA). However, some individuals with clonal disease have normal BST (<11.4 ng/mL). Objective. To evaluate whether screening for KIT p.D816V in the blood is a useful clinical tool to risk-stratify patients with venom allergy. Methods. We prospectively recruited 374 patients with Hymenoptera allergy and no overt signs of mastocytosis referred to our center in the years 2018-19. KIT p.D816V was determined in the peripheral blood with qPCR and tryptase genotyping was performed by droplet-digital PCR. Results. 351 patients (93.9%) had normal levels of BST and KIT p.D816V was detected in 8% of patients (28/351), predominantly in patients with the most severe Mueller grade IV anaphylaxis (18.2%[24/132] vs 1.8%[4/88 in grade III; 0/131 in other grades] in lower grades; P<0.001). In grade IV patients with normal BST, KIT p.D816V was associated with more severe symptoms including a significantly higher frequency of loss of consciousness (58.3%[14/24] vs 34.3%[37/108]; P=0.03) and absence of skin symptoms (41.7%[10/24] vs 15.7%[17/108]; P=0.004). Among patients with normal BST, KIT p.D816V (OR [95%CI]: 10.25[3.75-36.14]; P<0.0001) was the major risk factor associated with severe HVA. Hereditary [alpha]-tryptasemia (H[alpha]T), due to increased germline copies of TPSAB1 encoding [alpha]-tryptase was the most common cause (65.2%; 15/23) of elevated BST in patients with HVA and together with KIT p.D816V accounted for 90% (20/23) of BST elevations in HVA patients. Conclusion. These results indicate that routine KIT p.D816V screening identifies clonal disease in high-risk HVA patients regularly missed using BST alone.
Keywords: anaphylaxis, venoms, hypersensitivity, hereditary alpha-tryptasemia
DiRROS - Published: 31.03.2021; Views: 73; Downloads: 31

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