We detect EZH2 mutations in a significant proportion of BCL2-rearranged follicular lymphomas, BCL2-rearranged diffuse large B cell lymphomas, and high-grade B cell lymphomas with concurrent BCL2 and MYC rearrangements (so-called “double-hit lymphomas”), but not in BL. The gene discussed is BCL2; the disease is B-cell non-Hodgkin lymphoma.