showed that mast cell-deficient mice exhibited a decreased incidence of hyperglycemia-induced atrial fibrillation and interatrial conduction time as well as a diminished extent of atrial fibrosis, macrophage infiltration, and mRNA levels of TNF-α, MCP-1, IL-1β, TGF-β, and collagen-1 in the left atrium in STZ-induced DCM (65). The gene discussed is IL1B; the disease is familial dilated cardiomyopathy.