Rather, in symptomatic cases with SM and in SM cases in which tryptase levels are relatively high compared with the infiltration grade of the BM with neoplastic MC (eg, serum tryptase 120 ng/mL; BM infiltration grade 10%), tryptase genotyping should be considered because the likelihood of HαT is very high.48 This evidence concerns the gene TMPRSS11D and systemic mastocytosis.