In fact, when examining the promoter polymorphism −1112C > T (rs 1800925) in the IL13 gene in CM and SM patients [21], it appeared that the high transcription variant (−1112T) may be present more frequently in mastocytosis patients than in controls, and was significantly more common among patients with SM as compared to those with CM [27]. The gene discussed is IL13; the disease is systemic mastocytosis.