PGD2 release from PBLs of MCAS patients (mean: 1045 ± 280.3 pg/ml) was higher than that from PBLs of SM patients (mean: 829 ± 298.0 pg/ml), but the difference did not reach statistical significance (P = 0.096) (Figure 2A). The gene discussed is PTGDS; the disease is systemic mastocytosis.