Importantly, in the Spanish cohort (21), while a history of anaphylaxis at SM diagnosis was more frequent in HαT-positive participants, there was no higher incidence of new anaphylactic events during follow-up among HαT-positive SM patients as compared to HαT-negative SM patients, which advocates against HαT as a symptom modifier in mMCD. This evidence concerns the gene TMPRSS11D and systemic mastocytosis.