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) and 8q22.3 (rs2511714, P=2.90x10 -9 ). These findings provide further insights into the genetic and biological basis of inherited genetic susceptibility to CLL. Speedy et al 3Chronic lymphocytic leukemia (CLL) is the most common hematological malignancy in Western countries 1 and is characterized by a 8-fold increased risk in first-degree relatives 2 . Genome-wide association studies (GWASs) have so far identified common variants at 24 loci that contribute to the heritable risk of CLL [3][4][5][6] . Current projections for the number of independent regions harboring common variants associated with CLL suggest that additional risk loci conferring modest effects should be identified by expansion of discovery GWAS datasets.To identify additional novel susceptibility loci for CLL, we conducted an independent primary scan of CLL and performed a genome-wide meta-analysis with a previously published GWAS followed by analysis of the top single nucleotide polymorphisms (SNPs) in two separate case-control series.In the primary scan (UK-CLL-2), 1,271 CLL cases were genotyped using the Illumina Omni Express Figure 1). To harmonize the two GWAS datasets, we imputed UK-CLL-1 to recover untyped SNPs directly genotyped in UK-CLL-2, using data from the 1000 Genomes Project as reference. Using data on all cases and controls from each GWAS, we derived joint odds ratios (ORs) and confidence intervals (CIs) under a fixed effects model for each SNP and associated P-values, restricting analysis to SNPs with MAF >1%. After filtering on the basis of pre-specified quality-control measures Table 2). We also identified promising association signals (i.e. P<1.0×10−5 ) at 11 additional loci (Supplementary Table 2). We applied 1000 Genomes imputation to UK-CLL-1 and UK-CLL-2 at these loci to investigate if a statistically significant stronger SNP association could be identified, recovering an additional SNP which was significant at the genome-wide threshold (rs6858698; Supplementary Table 2). We performed replication genotyping of six SNPs selected on the basis of statistical significance (rs2236256, rs6062501, rs6858698) and gene centricity coupled with Table 4). While we found no evidence for a relationship between rs10936599, and telomere length in 246 CLL patients (Supplementary Table 5), carrier status for the rs10936599-C risk allele is previously been associated with significantly longer telomeres in leukocytes 10,11 .The third significant association was at rs6858698 on 4q26 (OR=1.31, 95% C.I. 1.20-1.44; P=3.07x10 linked to cis-platinum resistance by enhancing apoptosis. A recent GWAS of CLL has reported promising associations at 5p15.33 defined by rs10069690 and at 8q22.33 defined by rs2511714 6 . Combining the Pvalues for rs10069690 and rs2511714 obtained in our meta-analysis (P=1.0x10 -4 and 1.0x10respectively) with published data 6 provides robust evidence for both associations (combined P-values 1.10x10 -10 and 2.90x10 -9 respectively; Supplementary Figure 4). rs10069690 maps to intron 4 of TERT (telomerase reverse trans...

SRSF2 (SC35) is a key player in the regulation of alternative splicing events and binds degenerated RNA sequences with similar affinity in nanomolar range. We have determined the solution structure of the SRSF2 RRM bound to the 5'-UCCAGU-3' and 5'-UGGAGU-3' RNA, both identified as SRSF2 binding sites in the HIV-1 tat exon 2. RNA recognition is achieved through a novel sandwich-like structure with both termini forming a positively charged cavity to accommodate the four central nucleotides. To bind both RNA sequences equally well, SRSF2 forms a nearly identical network of intermolecular interactions by simply flipping the bases of the two consecutive C or G nucleotides into either anti or syn conformation. We validate this unusual mode of RNA recognition functionally by in-vitro and in-vivo splicing assays and propose a 5'-SSNG-3' (S=C/G) high-affinity binding consensus sequence for SRSF2. In conclusion, in addition to describe for the first time the RNA recognition mode of SRSF2, we provide the precise consensus sequence to identify new putative binding sites for this splicing factor.

Tra2-β1 is a unique splicing factor as its single RNA recognition motif (RRM) is located between two RS (arginine-serine) domains. To understand how this protein recognizes its RNA target, we solved the structure of Tra2-β1 RRM in complex with RNA. The central 5'-AGAA-3' motif is specifically recognized by residues from the β-sheet of the RRM and by residues from both extremities flanking the RRM. The structure suggests that RNA binding by Tra2-β1 induces positioning of the two RS domains relative to one another. By testing the effect of Tra2-β1 and RNA mutations on the splicing of SMN2 exon 7, we validated the importance of the RNA-protein contacts observed in the structure for the function of Tra2-β1 and determined the functional sequence of Tra2-β1 in SMN2 exon 7. Finally, we propose a model for the assembly of multiple RNA binding proteins on this exon.

Key Points• Germ line loss-of-function mutations in shelterin genes occur in a subset of families with CLL.• Telomere dysregulation is further implicated in CLL predisposition.Chronic lymphocytic leukemia (CLL) can be familial; however, thus far no rare germ line disruptive alleles for CLL have been identified. We performed whole-exome sequencing of 66 CLL families, identifying 4 families where loss-of-function mutations in protection of telomeres 1 (POT1) co-segregated with CLL. The p.Tyr36Cys mutation is predicted to disrupt the interaction between POT1 and the telomeric overhang. The c.1164-1G>A splice-site, p.Gln358SerfsTer13 frameshift, and p.Gln376Arg missense mutations are likely to impact the interaction between POT1 and adrenocortical dysplasia homolog (ACD), which is a part of the telomere-capping shelterin complex. We also identified mutations in ACD (c.752-2A>C) and another shelterin component, telomeric repeat binding factor 2, interacting protein (p.Ala104Pro and p.Arg133Gln), in 3 CLL families. In a complementary analysis of 1083 cases and 5854 controls, the POT1 p.Gln376Arg variant, which has a global minor allele frequency of 0.0005, conferred a 3.61-fold increased risk of CLL (P 5

Key Points• Somatic CDKN1B (p27) mutations were identified in 16% (13/81) of HCL patients and coexist with BRAFV600E mutations.• CDKN1B is the second most common mutated gene in HCL implicating altered cell cycle regulation and/or senescence in HCL.Hairy cell leukemia (HCL) is marked by near 100% mutational frequency of BRAFV600E mutations. Recurrent cooperating genetic events that may contribute to HCL pathogenesis or affect the clinical course of HCL are currently not described. Therefore, we performed whole exome sequencing to explore the mutational landscape of purine analog refractory HCL. In addition to the disease-defining BRAFV600E mutations, we identified mutations in EZH2, ARID1A, and recurrent inactivating mutations of the cell cycle inhibitor CDKN1B (p27). Targeted deep sequencing of CDKN1B in a larger cohort of HCL patients identify deleterious CDKN1B mutations in 16% of patients with HCL (n 5 13 of 81). In 11 of 13 patients the CDKN1B mutation was clonal, implying an early role of CDKN1B mutations in the pathogenesis of HCL. CDKN1B mutations were not found to impact clinical characteristics or outcome in this cohort. These data identify HCL as having the highest frequency of CDKN1B mutations among cancers and identify CDNK1B as the second most common mutated gene in HCL. Moreover, given the known function of CDNK1B, these data suggest a novel role for alterations in regulation of cell cycle and senescence in HCL with CDKN1B mutations. (Blood. 2015;126(8):1005-1008) IntroductionHairy-cell leukemia (HCL) is a rare, mature B-cell malignancy presenting with slow progressing pancytopenia and splenomegaly. Classical HCL is successfully treated with chemotherapy, but eradication of minimal residual disease is rarely achieved. 1 Standard treatment fails in a minority of patients, with a potentially fatal outcome.Gain-of-function mutations of the BRAF serine/threonine protein kinase (BRAFV600E) have been identified in nearly all cases of classical HCL, and mitogen-activated protein kinase signaling is considered the key oncogenic pathway in HCL.2 Chung et al 3 recently identified hematopoietic stem cells as the cell of origin of HCL by demonstrating that hematopoietic stem cells, and subsequently cells along the hematopoietic hierarchy, contain mutated BRAF. Currently, however, no other recurrently mutated genes are known to coexist with BRAFV600E mutations in HCL. It is unclear if BRAFV600E mutations alone are sufficient to induce HCL. Moreover, it is also not known if additional mutations may be acquired in BRAFV600E-mutant HCL cells, resulting in acquired resistance to therapies commonly administered to patients with HCL such as purine analogs. Therefore, we performed whole-exome sequencing (WES) in 3 HCL patients who were refractory to purine analog treatment and received the BRAF inhibitor (BRAFi) vemurafenib followed by recurrence testing of novel mutations in a larger cohort of HCL patients. Study designClinical samples were provided by

The BCL-2-specific inhibitor, ABT-199 (venetoclax) has exhibited remarkable clinical activity in nearly all cases of chronic lymphocytic leukemia. In contrast, responses are usually much less in diffuse large B-cell lymphoma (DLBCL), despite high level expression of BCL-2 in over 40% of cases, indicating that co-expression of related anti-apoptotic BCL-2 family proteins may limit the activity of ABT-199. We have investigated the roles of BCL-2 proteins in DLBCL cells using a panel of specific BCL-2 homology 3 (BH3)-mimetics and identified subgroups of these cells that exhibited marked and specific dependency on either BCL-2, BCL-X L or MCL-1 for survival. Dependency was associated with selective sequestration of the pro-apoptotic proteins BIM, BAX and BAK by the specific anti-apoptotic BCL-2 protein which was important for cellular survival. Sensitivity to BH3-mimetics was independent of genetic alterations involving the BCL-2 family and only partially correlated with protein expression levels. Treatment with ABT-199 displaced BAX and BIM from BCL-2, subsequently leading to BAK activation and apoptosis. In contrast, apoptosis induced by inhibiting BCL-X L with A1331852 was associated with a displacement of both BAX and BAK from BCL-X L and occurred independently of BIM. Finally, the MCL-1 inhibitor S63845 induced mainly BAX-dependent apoptosis mediated by a displacement of BAK, BIM and NOXA from MCL-1. In conclusion, our study indicates that in DLBCL, the heterogeneous response to BH3-mimetics is mediated by selective interactions between BAX, BAK and anti-apoptotic BCL-2 proteins.

Several chronic lymphocytic leukaemia (CLL) susceptibility loci have been reported; however, much of the heritable risk remains unidentified. Here we perform a meta-analysis of six genome-wide association studies, imputed using a merged reference panel of 1,000 Genomes and UK10K data, totalling 6,200 cases and 17,598 controls after replication. We identify nine risk loci at 1p36.11 (rs34676223, P=5.04 × 10-13), 1q42.13 (rs41271473, P=1.06 × 10-10), 4q24 (rs71597109, P=1.37 × 10 -10), 4q35.1 (rs57214277, P=3.69 × 10-8), 6p21.31 (rs3800461, P=1.97 × 10-8), 11q23.2 (rs61904987, P=2.64 × 10-11), 18q21.1 (rs1036935, P=3.27 × 10-8), 19p13.3 (rs7254272, P=4.67 × 10-8) and 22q13.33 (rs140522, P=2.70 × 10-9). These new and established risk loci map to areas of active chromatin and show an over-representation of transcription factor binding for the key determinants of B-cell development and immune response