This is a mast-cell system failure. The cells are genetically abnormal, over-numerous, and they release the wrong mediators in the wrong proportions. This is typically due to an activating mutation in KIT (D816V) or an increased copy number of TPSAB1. Normal mast cellClonal mast cellActivation thresholdHighAbnormally lowMast-cell burdenNormalMassively increasedDegranulation patternHistamine-dominantTryptase

Is this anaphylaxis driven by clonal mast-cell disease? REMA Score Gender * Male: * +1 point * Female: * -1 point Clinical Symptoms * Pruritus/Hives/Angioedema: * Presence (-2) * Absence (+1) * Presyncope/Syncope: * Presence (+3)  Serum Tryptase * Serum Tryptase: * <15 µg/l (-1) * >25 µg/l (+2) Score Interpretation * Score ≥2 = A high