EZH2 mutations are frequent and represent an early event in follicular lymphoma
Gain of function mutations in the H3K27 methyltransferase EZH2 represent a promising therapeutic target in germinal center lymphomas. In this study, we assessed the frequency and distribution of EZH2 mutations in a large cohort of patients with follicular lymphoma (FL) (n = 366) and performed a longitudinal analysis of mutation during the disease progression from FL to transformed FL (tFL) (n = 33). Mutations were detected at 3 recurrent mutation hot spots (Y646, A682, and A692) in 27% of FL cases with variant allele frequencies (VAF) ranging from 2% to 61%. By comparing VAF of EZH2 with other mutation targets (CREBBP, MLL2, TNFRSF14, and MEF2B), we were able to distinguish patients harbori…
Whole-epigenome analysis in multiple myeloma reveals DNA hypermethylation of B cell-specific enhancers
Abstract Analyzing the DNA methylome of multiple myeloma (MM), a plasma cell neoplasm, by whole-genome bisulfite sequencing and high-density arrays, we observed regional DNA hypermethylation embedded in extensive global hypomethylation. In contrast to the widely reported DNA hypermethylation of promoter-associated CpG islands (CGIs) in cancer, hypermethylated sites in MM as compared to normal plasma cells were located outside CpG islands and were unexpectedly associated with intronic enhancer regions active in normal B cells. Both RNA-seq and in vitro reporter assays indicated that enhancer hypermethylation is globally associated with downregulation of its host genes. ChIP-seq and DNAseI-se…
Genome-wide association study identifies multiple risk loci for chronic lymphocytic leukemia
Genome-wide association studies (GWAS) have previously identified 13 loci associated with risk of chronic lymphocytic leukemia or small lymphocytic lymphoma (CLL). To identify additional CLL susceptibility loci, we conducted the largest meta-analysis for CLL thus far, including four GWAS with a total of 3,100 individuals with CLL (cases) and 7,667 controls. In the meta-analysis, we identified ten independent associated SNPs in nine new loci at 10q23.31 (ACTA2 or FAS (ACTA2/FAS), P = 1.22 × 10-14), 18q21.33 (BCL2, P = 7.76 × 10-11), 11p15.5 (C11orf21, P = 2.15 × 10 -10), 4q25 (LEF1, P = 4.24 × 10-10), 2q33.1 (CASP10 or CASP8 (CASP10/CASP8), P = 2.50 × 10-9), 9p21.3 (CDKN2B-AS1, P = 1.27 × 10…
Cryptic Insertions Of The Immunoglobulin Light Chain Enhancer Region Near CCND1 In T(11;14)-Negative Mantle Cell Lymphoma
Cyclin D1+ mantle cell lymphoma (MCL) is molecularly characterized by the t(11;14)(q13;q32) or rearrangements of CCND1 gene with the immunoglobulin (IG) light chains.1,2 Most MCL can be diagnosed based on the characteristic pathologic features and cyclin D1 expression without the need for demonstrating the genetic translocation. However, in cases with atypical morphologic or phenotypic features other B-cell neoplasms that sometimes also have cyclin D1 positivity may be in the differential diagnosis.1 In these situations the detection of the CCND1 rearrangements may assist in the diagnosis since most other lymphomas do not carry translocations of the gene.3-7 A subset of plasma cell myelomas…
Distinctive Histogenesis and Immunological Microenvironment Based on Transcriptional Profiles of Follicular Dendritic Cell Sarcomas
Abstract Follicular dendritic cell (FDC) sarcomas are rare mesenchymal tumors with variable clinical, morphologic, and phenotypic characteristics. Transcriptome analysis was performed on multiple FDC sarcomas and compared with other mesenchymal tumors, microdissected Castleman FDCs, and normal fibroblasts. Using unsupervised analysis, FDC sarcomas clustered with microdissected FDCs, distinct from other mesenchymal tumors and fibroblasts. The specific endowment of FDC-related gene expression programs in FDC sarcomas emerged by applying a gene signature of differentially expressed genes (n = 1,289) between microdissected FDCs and fibroblasts. Supervised analysis comparing FDC sarcomas with mi…