Figure 2.
Hereditary α tryptasemia is associated with indolent systemic mastocytosis. (A) Distribution of the mastocytosis disease subtype in patients without α-tryptase encoding TPSAB1 gain (upper bar), any α allele TPSAB1 gain (middle bar), and ≥3 α-allelic copies (lower bar). Serum tryptase (B) and bone marrow mast cell infiltration (C) in ISM/SSM patients with (blue) and without (green) α-tryptase encoding TPSAB1 gain. Samples of SSM patients are shown in orange. Vertical black lines indicate mean ± standard error of the mean. The dotted black line indicates 20 ng/mL serum tryptase as minor diagnostic criterion for SM, and the dotted orange lines indicate B-finding defining cutoffs (200 ng/mL serum tryptase and 30% mast cell infiltration, respectively). *P < .05.