IGR_U985_CLL_Exome

Chronic lymphocytic leukemia (CLL), the most frequent adult leukemia in western countries, is a clonal accumulation of mature B-lymphocytes and its natural history is yet unclear. By using sequencing and cellular biology approaches on a cohort of CLL patient samples, we show here that acquired CLL mutations are observed in hematopoietic multipotent progenitor fractions in the majority of patients. These early CLL mutations include recurrent inactivating mutations in NFKBIE (10.7%) and missense mutations in BRAF (3.6%) and EGR2 (8.3%). Functional analyses demonstrated that BRAF-G469R affects lymphoid differentiation and transforms the T-cell lineage in vivo. In addition, the EGR2 recurrent mutations were associated with transcriptional activation of EGR2 target genes in patients and cell cycle abnormality in cellular model. Our findings indicate that CLL may develop from an initial infra-clinic, pre-leukemic phase affecting immature hematopoietic cells. The aim of this study is to compare exome sequences from tumor cells and T-lymphocytes in order to predict somatic mutations in 24 CLL patients (17 IGHV-unmutated and 7 IGHV-mutated). Enriched exome fragments were subjected to massively parallel sequencing using HiSeq 2000 (Illumina).