Recently, Momose et al sequenced relevant genes that are frequently mutated in BL (ID3, TCF3, CCND3 and MYC) and DLBCL (BCL2, EZH2, CREBBP, EP300, MEF2B and SGK1) in 108 aggressive B-cell lymphomas including 31 BL, 24 BCL-U and 53 DLBCL cases, and found that the morphological, immunophenotypic and genetic gray zone between BL and DLBCL is also a gray zone of the mutational spectrum. The gene discussed is MEF2B; the disease is Burkitt lymphoma.