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Background & Aims Non-alcoholic fatty liver disease (NAFLD) is a multifactorial disorder resulting from genetic and environmental factors. Hyperferritinemia has been associated with increased hepatic iron stores and worse outcomes in patients with NAFLD. The aim of this study was to evaluate the prevalence of variants of iron-related genes and their association with hyperferritinemia, hepatic iron stores and liver disease severity in patients with NAFLD. Methods From a cohort of 328 individuals with histological NAFLD, 23 patients with ferritin >750 ng/ml and positive iron staining, and 25 controls with normal ferritin and negative iron staining, were selected. Patients with increased transferrin saturation, anemia, inflammation, β-thalassemia trait, HFE genotype at risk of iron overload and ferroportin mutations were excluded. A panel of 32 iron genes was re-sequenced. Literature and in silico predictions were employed for prioritization of pathogenic mutations. Results Patients with hyperferritinemia had a higher prevalence of potentially pathogenic rare variants (73.9% vs. 20%, p = 0.0002) associated with higher iron stores and more severe liver fibrosis (p Conclusions Variants in non-HFE iron genes, particularly ceruloplasmin, are associated with hyperferritinemia and increased hepatic iron stores in patients with NAFLD. Carriers of such variants have more severe liver fibrosis, suggesting that genetic predisposition to hepatic iron deposition may translate into liver disease. Lay summary Non-alcoholic fatty liver disease (NAFLD) is a common disease which can progress to cirrhosis and liver cancer. Increased levels of serum ferritin are often detected in patients with NAFLD and have been associated with altered iron metabolism and worse patient outcomes. We found that variants of genes related to iron metabolism, particularly ceruloplasmin, are associated with high ferritin levels, hepatic iron deposition and more severe liver disease in an Italian cohort of patients with NAFLD.

The standard of care for breast cancer has gradually evolved from empirical treatments based on clinical-pathological characteristics to the use of targeted approaches based on the molecular profile of the tumor. Consequently, an increasing number of molecularly targeted drugs have been developed. These drugs target specific alterations, called driver mutations, which confer a survival advantage to cancer cells. To date, the main challenge remains the identification of predictive biomarkers for the selection of the optimal treatment. On this basis, we evaluated a panel of 25 genes involved in the mechanisms of targeted treatment resistance, in 16 primary breast cancers and their matched recurrences, developed during treatment. Overall, we found a detection rate of mutations higher than that described in the literature. In particular, the most frequently mutated genes were ERBB2 and those involved in the PI3K/AKT/mTOR and the MAPK signaling pathways. The study revealed substantial discordances between primary tumors and metastases, stressing the need for analysis of metastatic tissues at recurrence. We observed that 85.7% of patients with an early-stage or locally advanced primary tumor showed at least one mutation in the primary tumor. This finding could explain the subsequent relapse and might therefore justify more targeted adjuvant treatments. Finally, the mutations detected in 50% of relapsed tissues could have guided subsequent treatment choices in a different way. This study demonstrates that mutation events may be present at diagnosis or arise during cancer treatment. As a result, profiling primary and metastatic tumor tissues may be a major step in defining optimal treatments.

Transformation to secondary myelofibrosis (MF) occurs as part of the natural history of polycythemia vera (PPV-MF) and essential thrombocythemia (PET-MF). Although primary (PMF) and secondary MF are considered similar diseases and managed similarly, there are few studies specifically focused on the latter. The aim of this study was to characterize the mutation landscape, and describe the main clinical correlates and prognostic implications of mutations, in a series of 359 patients with PPV-MF and PET-MF. Compared with PV and ET, the JAK2V617F and CALR mutated allele burden was significantly higher in PPV-MF and/or PET-MF, indicating a role for accumulation of mutated alleles in the process of transformation to MF. However, neither the allele burden nor the type of driver mutation influenced overall survival (OS), while absence of any driver mutation (triple negativity) was associated with significant reduction of OS in PET-MF, similar to PMF. Of the five interrogated subclonal mutations (ASXL1, EZH2, SRSF2, IDH1, and IDH2), that comprise a prognostically detrimental high molecular risk (HMR) category in PMF, only SRSF2 mutations were associated with reduced survival in PET-MF, and no additional mutation profile with prognostic relevance was highlighted. Overall, these data indicate that the molecular landscape of secondary forms of MF is different from PMF, suggesting that unknown mutational events might contribute to the progression from chronic phase disease to myelofibrosis. These findings also support more extended genotyping approaches aimed at identifying novel molecular abnormalities with prognostic relevance for patients with PPV-MF and PET-MF. Am. J. Hematol. 91:681-686, 2016. © 2016 Wiley Periodicals, Inc.

Frost resistance-H2 (Fr-H2) is a major QTL affecting freezing tolerance in barley, yet its molecular basis is still not clearly understood. To gain a better insight into the structural characterization of the locus, a high-resolution linkage map developed from the Nure × Tremois cross was initially implemented to map 13 loci which divided the 0.602 cM total genetic distance into ten recombination segments. A PCR-based screening was then applied to identify positive bacterial artificial chromosome (BAC) clones from two genomic libraries of the reference genotype Morex. Twenty-six overlapping BACs from the integrated physical-genetic map were 454 sequenced. Reads assembled in contigs were subsequently ordered, aligned and manually curated in 42 scaffolds. In a total of 1.47 Mbp, 58 protein-coding sequences were identified, 33 of which classified according to similarity with sequences in public databases. As three complete barley C-repeat Binding Factors (HvCBF) genes were newly identified, the locus contained13 full-length HvCBFs, four Related to AP2 Triticeae (RAPT) genes, and at least five CBF pseudogenes. The final overall assembly of Fr-H2 includes more than 90 % of target region: all genes were identified along the locus, and a general survey of Repetitive Elements obtained. We believe that this gold-standard sequence for the Morex Fr-H2 will be a useful genomic tool for structural and evolutionary comparisons with Fr-H2 in winter-hardy cultivars along with Fr-2 of other Triticeae crops.

With the intent of dissecting the molecular complexity of Philadelphia-negative myeloproliferative neoplasms (MPN), we designed a target enrichment panel to explore, using next-generation sequencing (NGS), the mutational status of an extensive list of 2000 cancer-associated genes and microRNAs. The genomic DNA of granulocytes and in vitro-expanded CD3+T-lymphocytes, as a germline control, was target-enriched and sequenced in a learning cohort of 20 MPN patients using Roche 454 technology. We identified 141 genuine somatic mutations, most of which were not previously described. To test the frequency of the identified variants, a larger validation cohort of 189 MPN patients was additionally screened for these mutations using Ion Torrent AmpliSeq NGS. Excluding the genes already described in MPN, for 8 genes (SCRIB, MIR662, BARD1, TCF12, FAT4, DAP3, POLG and NRAS), we demonstrated a mutation frequency between 3 and 8%. We also found that mutations at codon 12 of NRAS (NRASG12V and NRASG12D) were significantly associated, for primary myelofibrosis (PMF), with highest dynamic international prognostic scoring system (DIPSS)-plus score categories. This association was then confirmed in 66 additional PMF patients composing a final dataset of 168 PMF showing a NRAS mutation frequency of 4.7%, which was associated with a worse outcome, as defined by the DIPSS plus score.

To assess the clinical utility of targeted Next-Generation Sequencing (NGS) for the diagnosis of Inherited Retinal Dystrophies (IRDs), a total of 109 subjects were enrolled in the study, including 88 IRD affected probands and 21 healthy relatives. Clinical diagnoses included Retinitis Pigmentosa (RP), Leber Congenital Amaurosis (LCA), Stargardt Disease (STGD), Best Macular Dystrophy (BMD), Usher Syndrome (USH), and other IRDs with undefined clinical diagnosis. Participants underwent a complete ophthalmologic examination followed by genetic counseling. A custom AmpliSeq™ panel of 72 IRD-related genes was designed for the analysis and tested using Ion semiconductor Next-Generation Sequencing (NGS). Potential disease-causing mutations were identified in 59.1% of probands, comprising mutations in 16 genes. The highest diagnostic yields were achieved for BMD, LCA, USH, and STGD patients, whereas RP confirmed its high genetic heterogeneity. Causative mutations were identified in 17.6% of probands with undefined diagnosis. Revision of the initial diagnosis was performed for 9.6% of genetically diagnosed patients. This study demonstrates that NGS represents a comprehensive cost-effective approach for IRDs molecular diagnosis. The identification of the genetic alterations underlying the phenotype enabled the clinicians to achieve a more accurate diagnosis. The results emphasize the importance of molecular diagnosis coupled with clinic information to unravel the extensive phenotypic heterogeneity of these diseases.

Summary Background Epidermolysis bullosa (EB) is caused by mutations in genes that encode proteins belonging to the epidermal–dermal junction assembly. Due to the extreme clinical/genetic heterogeneity of the disease, the current methods available for diagnosing EB involve immunohistochemistry of biopsy samples and transmission electron microscopy followed by single-candidate gene Sanger sequencing (SS), which are labour-intensive and expensive clinical pathways. Objectives According to the recently published recommendations for the diagnosis and treatment of EB, the assessment of the mutational landscape is now a fundamental step for developing a comprehensive diagnostic path. We aimed to develop a customized, cost-effective amplicon panel for the complete and accurate sequencing of all the pathogenic genes already identified in EB, and to minimize the processing time required for the execution of the test and to refine the analysis pipeline to achieve cost-effective results from the perspective of a routine laboratory set-up. Next-generation sequencing (NGS) via the parallel ultra-deep sequencing of many genes represents a proper method for reducing the processing time and costs of EB diagnostics. Materials and methods We developed an EB disease-comprehensive AmpliSeq panel to accomplish the NGS on an Ion Torrent Personal Genome Machine platform. The panel was performed on 10 patients with known genetic diagnoses and was then employed in eight family trios with unknown molecular footprints. Results The panel was successful in finding the causative mutations in all 10 patients with known mutations, fully confirming the SS data and providing proof of concept of the sensitivity, specificity and accuracy of this procedure. In addition to being consistent with the clinical diagnosis, it was also effective in the trios, identifying all of the variants, including ones that the SS missed or de novo mutations. Conclusions The NGS and AmpliSeq were shown to be an effective approach for the diagnosis of EB, resulting in a cost- and time-effective 72-h procedure.

RBM5, a regulator of alternative splicing of apoptotic genes, and its highly homologous RBM6 and RBM10 are RNA-binding proteins frequently deleted or mutated in lung cancer. We report that RBM5/6 and RBM10 antagonistically regulate the proliferative capacity of cancer cells and display distinct positional effects in alternative splicing regulation. We identify the Notch pathway regulator NUMB as a key target of these factors in the control of cell proliferation. NUMB alternative splicing, which is frequently altered in lung cancer, can regulate colony and xenograft tumor formation, and its modulation recapitulates or antagonizes the effects of RBM5, 6, and 10 in cell colony formation. RBM10 mutations identified in lung cancer cells disrupt NUMB splicing regulation to promote cell growth. Our results reveal a key genetic circuit in the control of cancer cell proliferation. E.B. was supported by a Marie Curie postdoctoral fellowship (FP7-PEOPLE-2009-IEF). Work in E.E.’s group is supported by Consolider RNAREG, BIO2011-23920, and FSI2011-035 from Sandra Ibarra/nFoundation. Work in J.V.’s lab is supported by Fundación Botín, AICR, Fundación Alicia Koplowitz, Consolider RNAREG, and Ministerio de Economía y Competitividad.

Background Ruxolitinib (RUX) is a JAK1 & JAK2 inhibitor that resulted in rapid and durable reductions in splenomegaly and improved disease-related symptoms and quality of life in patients (pts) with myelofibrosis (MF) compared with either placebo (COMFORT-I) or best available therapy (BAT; COMFORT-II). In addition, RUX-treated pts had longer overall survival (OS) compared with placebo and BAT. We recently reported that, among 879 primary MF pts receiving conventional BAT, those harboring a mutation in any one of EZH2, ASXL1, IDH1/2 and SRSF2 constituted an IPSS- and DIPSS-plus prognostic score–independent “high molecular risk” (HMR+) category associated with shorter OS and greater risk of leukemia compared with pts with no mutations (“low molecular risk”; LMR) (Vannucchi AM, et al. Leukemia. 2013). The aim of this study was to analyze the impact of mutational status on spleen volume reduction, anemia development, and OS in pts receiving RUX in the COMFORT II trial. Patients and methods In COMFORT-II, pts with primary or post–polycythemia vera/–essential thrombocythemia MF were randomized to receive RUX (n=146) or BAT (n=73). Mutations in 12 genes (JAK2, MPL, EZH2, ASXL1, TET2, IDH1/2, CBL, SRSF2, SOCS1, SOCS2, SOCS3, and SH2B3) were genotyped, in DNA derived from whole blood, at baseline in 166 pts (RUX n=120, BAT n=46). Analysis was performed by next-generation sequencing with the Ion Torrent PGM or Roche 454 platform. Sequencing data were analyzed with Nextgene software or Roche 454 Analysis software v2.6 with variant frequency cutoff adjusted to 5%. All mutations were confirmed at least twice. Missense, nonsense, and frameshift mutations only were considered; in the case of novel mutations, SNPs were excluded by database searching and by germline DNA genotyping when available. Development of anemia was defined as a drop of hemoglobin level by more than 1 g/dL from baseline to a value Results The frequency of mutations was: JAK2V617F 75.47%; MPLW515 7.74%; ASXL1 32.53%; TET2 10.69%; EZH2 7.24%; CBL 4.4%; SRSF2 3.01%; SH2B3 1.3%; IDH1-2 0.7%; SOCS1 0.65%; SOCS2 0.65%; SOCS3 0.0%, with no difference between RUX and BAT. Forty-six (38.3%) and 20 (43.5%) pts in the RUX and BAT groups, respectively, were classified as HMR+. We first determined whether an HMR+ status impacted the achievement of a ≥35% spleen volume reduction (primary study endpoint). The percentage of RUX treated pts achieving ≥35% spleen volume reduction was 36.3% (16/44) and 33.8% (21/62) at 24 wk and 30.7% (12/39) and 36.3% (20/55) at 48 wk in the HMR+ and LMR categories, respectively. Mean spleen volume reduction was also similar: -29.0% and -23.5% in HMR+ vs -29.9% and -30.6% in LMR pts at 24 and 48 wk. None of the other mutations analyzed correlated with spleen volume reduction in pts receiving RUX. We also found that an HMR+ status did not predict for the development of anemia associated with RUX administration: the percentage of anemic pts was 74% in the HMR+ group vs 72% in the LMR group. This was also independent of the presence of mutation in any one of the genes associated with JAK2/STAT signaling (JAK2, MPL, SH3B2, CBL, and SOCSs): anemic pts were 74% in mutated vs 72% in wild-type ones. The survival estimate at 114 wk of follow-up in BAT pts was 0.58 and 0.71 in HMR+ and LMR pts, confirming the negative impact of the mutational risk category. In the RUX arm, the survival estimate was 0.79 and 0.85 for HMR+ and LMR pts, indicating a benefit of RUX treatment in both groups. In the multivariate Cox model, a risk of death with RUX compared with BAT was reduced by 43% (HR=0.57, 95% CI: 0.30-1.08) and LMR patients had a reduction in risk compared with HMR+ by 38% (HR=0.62, 95% CI: 0.33-1.16; Figure). Conclusions The prognostic value of detrimental mutations comprising an HMR+ category in MF was maintained within this subset of COMFORT II patients. The results suggest that the negative impact of HMR+ status on survival in MF pts in COMFORT-II is halved by treatment with RUX compared with BAT and that the effect of RUX is similar in both the HMR+ and LMR groups; in addition, HMR+ status did not affect the likelihood of obtaining a ≥35% spleen volume reduction nor the risk of developing anemia under treatment. Disclosures: Stalbovskaya: Novartis Pharma AG: Employment, Equity Ownership. Squires:Novartis Pharma AG: Employment. Harrison:NOVARTIS: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding, Speakers Bureau; Sanofi: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau; YM Bioscience: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Celgene: Honoraria; Shire: Speakers Bureau; Sbio: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity’s Board of Directors or advisory committees. Vannucchi:NOVARTIS: Honoraria, Membership on an entity’s Board of Directors or advisory committees.

Background: We reported that mutations in ASXL1, EZH2, IDH1/2 and SRSF2 are negative prognostic variables for survival in primary myelofibrosis (PMF). Patients harboring any one of these mutations comprise IPSS and DIPSS-plus independent high molecular risk (HMR) category. Conversely, prognostic variables in secondary myelofibrosis (sMF), including post-polycythemia vera (PPV) and post-essential thrombocythemia (PET) MF are not defined. Aims: The aim was to evaluate the correlations of HMR mutational status with hematologic characteristics and clinical presentation, and the role for outcome predition, in PPV- and PET-MF. Methods: PPV- and PET-MF were diagnosed by IWG-MRT criteria; all pts provided informed consent. Previously published methods were used to screen mutations involving JAK2,MPL, CALR, EZH2, ASXL1, IDH1/2 and SRSF2. The prognostic value of the molecular variables with regard to OS was estimated by the Kaplan-Meier method and Cox regression. Results: A series of 200 sMF pts from 3 Italian centres was collected: 108 were PPV-MF (54%), 92 PET-MF (46%). PPV-MF cohort: Median age was 65y. Median follow up from PPV-MF diagnosis 4.7y (0.2-25.9y) and median time from PV to PPV-MF 10y (1.08-30.7y). Death occurred in 34 pts (31.8%), 7 pts (6.5%) developed leukemia. Median OS from PPV-MF diagnosis was 9.5y (7.1-11.9y). Frequency of mutations was: JAK2V617F 100% (median allele burden 77%, range 23-100), ASXL1 17.8%, EZH2 3.7%, IDH 5.6%, SRSF2 1%; 29 patients (26.9%) were classified as HMR cases. Hematologic characteristics: median leucocytes 13.0x109/L, hemoglobin 13.3g/dL, platelets 328x109/L, blasts ≥1% 23.4%. Constitutional symptoms in 45.8%, splenomegaly 94.1% (43.3% >10cm from LCM), pruritus 49%; median percentage of BM cellularity was 90% (25-100%) and grade 3 fibrosis in 16.8%. Overall 73 patients were evaluable for karyotype and abnormalities were detected in 42.5%. We did not find significant correlations between individual mutations or HMR category and hematologic and clinical characteristics. PET-MF cohort: Median age was 63.6y. Median follow up from the PET diagnosis 3.3y (0.2-14.5y), median time from ET to PET-MF 11.8y (0.9-30.6y). Death occurred in 30 pts (32.6%), 11 pts (12.0%) developed leukemia. Median OS from PET-MF diagnosis was 9.2y (4.9-13.6y). Frequency of mutations was: JAK2V617F 48.9% (median allele burden 49%, range 0-100), CALR 40.2%, MPL 4.3% and triple negativity (TN) 6.5%; ASXL1 29.3%, EZH2 6.5%, IDH 1.1%, SRSF2 3.3%; 33 pts (35.9%) were HMR. Hematologic characteristics: median leucokytes 8.0x109/L, hemoglobin 10.9 g/dL, platelets 375x109/L, blasts ≥1% 26.4%. Constitutional symptoms 35.4% of pts, splenomegaly 82% (18.2% >10cm from LCM), pruritus i31%; median percentage of BM cellularity was 70% (15-90%) and grade 3 fibrosis was found in 31.7%. Overall 56 patients were evaluable for karyotype and abnormalities were detected in 25.0%. By correlating hematologic and clinical characteristics with unique mutations and HMR category, we found that HMR mutated pts presented greater leukocytosis (P=0.04) and higher JAK2V617F allele burden (P=0.017) than pts in the low-molecular risk –LMR- category (ie, wild-type for ASXL1, EZH2, SRSF2, IDH1/2). Comparison of PPV-MF and PET-MF: a comparison of hematologic and clinical characteristics according to the diagnosis sMF disclosed that PPV-MF pts presented more frequently splenomegaly (P=0.008; for >10cm from LCM P Univariate analysis disclosed significant correlations between shortened survival and mutated ASXL1 (P=0.02, HR 2.2 95% CI, 1.02-4.8) or EZH2 (P=0.05, HR 5.0 95% CI, 1.0-40.7) in PPV-MF. A HMR category was associated with reduced survival in PPV-MF: median survival 6.1y versus 9.5yr LMR (HR 1.07, 95%CI 1.0-4.4; P=0.04). In PET-MF survival was 4.8y in HMR versus 10.9y in LMR (HR1.6, 95%CI 0.8-3.4; P=0.2). Conclusion: We conclude that a HMR status is associated with shorter survival in sMF, but the overal impact is narrower than in primary MF, even though the rate of mutations is similar (Table1). Disclosures No relevant conflicts of interest to declare.

BACKGROUND. In primary myelofibrosis (PMF), survival from time of diagnosis is predicted by the international prognostic scoring system (IPSS), and from time of referral, by the dynamic IPSS (DIPSS) or DIPSS-plus. JAK2/CALR/MPL mutational status and presence and number of other prognostically-relevant mutations (ASXL1, SRSF2, EZH2, IDH1/2) provide IPSS/DIPSS-plus independent prognostic information. The objective in the current study was to revise IPSS, by including mutation-relevant prognostic information. METHODS. The study included 986 PMF patients divided into learning (n=588) and validation (n=398) cohorts. Previously published methods were used to screen for mutations involving JAK2,MPL, CALR, EZH2, ASXL1, IDH1/2 and SRSF2. The clinical variables assessed were those previously identified as being prognostically-relevant by IPSS or DIPSS-plus. The prognostic model (MIPSS) was developed through a stepwise selection process, based on a z-test of the regression coefficients, and its relative quality was measured by means of the Akaike information criterion. RESULTS. In the Italian learning cohort (n=588),median follow-up was 3.6years (95% CI, 0.03-30.8) for alive patients and 196 (33.3%) deaths and 67 leukemic transformations were documented. IPSS risk distribution was low in 26%, intermediate-1 in 30%, intermediate-2 in 24% and high in 20%. Mutational frequencies were approximately 63% for JAK2, 20% CALR, 6% MPL, 7% EZH2, 22% ASXL1, 2.5% IDH1/2 and 9% SRSF2. Constitutional symptoms were recorded in 28.6% of patients, splenomegaly 75% (18% >10cm from LCM) and grade 3 fibrosis 21%. Overall 252 patients were evaluable for karyotype and abnormalities were detected in 35%, including 9.5% unfavorable. Univariate analysis identified the following risk factors for inferior survival: age >60 years, constitutional symptoms, hemoglobin 25x109/L, platelets 10cm, grade 3 fibrosis, unfavorable karyotype, triple-negativity for JAK2, MPL and CALR (TN), JAK2 or MPL mutation, and mutations in ASXL1, SRSF2, EZH2 or IDH1/2. In multivariable analysis, age >60 years, constitutional symptoms, hemoglobin In the Mayo Clinic validation cohort (n=398), median age 63 years; males 64%,median follow-up for alive patients was 7.5 years and 271 (68%) deaths and 51 (13%) leukemic transformations were documented. DIPSS-plus risk distribution was low in 13%, intermediate-1 18%, intermediate-2 37% and high 32%. Mutational frequencies were approximately 51% for JAK2, 30% CALR, 7.5% MPL, 5% EZH2, 36% ASXL1, 5.6% IDH1/2 and 13% SRSF2. MIPSS performed equally well in this cohort, as illustrated in figure 1B, which includes number of patients in each risk category with their median survival and HR and 95% CI values. Leukemia-free survival in the Mayo cohort was also predicted by high (p CONCLUSIONS. MIPSS addresses the mutation-relevant prognostic information gap in IPSS and performs equally well in the setting of patients seen at time of diagnosis or referral. Karyotype carries MIPSS-independent prognostic value that is recognized in an alternative GIPSS prognostic model (see accompanying ASH 2014 abstract), which complements MIPSS. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

The discovery of the JAK2V617F mutation in 2005 [Kralovics R, N Engl J Med 2005] represented a major breakthrough in the understanding of the molecular pathogenesis of Philadelphia chromosome negative chronic myeloproliferative neoplasms (MPN). Nevertheless several observations suggest that the JAK2V617F mutation may not be the disease funding mutation, at least in most instances. Therefore, a great deal of effort is ongoing with the aim to identifying novel genetic lesions contributing to the disease pathogenesis. The two major theoretical and technical drawbacks to the identification of new somatic mutations are represented, respectively, by the huge number of genes potentially involved in tumorigenesis of MPN and by the availability of a “pure” germline control DNA. Buccal swabs and saliva have been generally considered as readily available sources of DNA of non-hematopoietic origin, but detection of the JAK2V617F mutation in at least some of these samples indeed suggested the presence of myeloid cell contamination [Levine RL, Cancer Cell 2005]. So, in order to discover novel mutations in MPN using upfront technologies based on next-generation sequencing (NGS) we designed a “cancer exome” capture panel of 2000 unique genes and microRNAs. This panel was used to capture libraries generated from genomic DNA extracted from granulocytes and in vitro expanded CD3+ T-lymphocytes as germline control, in a cohort of 20 MPN patients. These captured libraries were than massively sequenced using the Roche 454 FLX platform. DNA samples had been collected at the diagnosis of PV in 9 subjects and PMF in 6 subjects, while the remaining 5 DNA samples were from 5 of the 9 PV patients at the time they evolved to post-PV myelofibrosis. After extensive bioinformatics analysis and multiple control adjustments, we finally produced a list of 171 novel “true” somatic mutations occurring in genes and microRNAs coding regions of those MPN samples; some of these mutations have been already described in MPN, whereas novel variants represent the vast majority. Despite patients harbored different numbers of somatic mutations, spanning from four to twenty-one variants, only 22 genes appear recurrently mutated. It is worth of notice the acquisition of additional mutations and/or the occurrence of loss of some mutations at the time of disease evolution from PV to a post-PV Myelofibrosis in the five patients for whom samples were available at both disease phases. Some of them, either acquired (NTRK1, PRDM2, BRCA2 and BARD1) or lost (APC, CARS, MLL3 and FAT2) had been found also in another PV or PMF sample. To test the recurrence of these mutations, we screened a different cohort of 189 patients composed by PMF (91 samples), PV (50 patients) and post-PV Myelofibrosis (48 samples) by Ion AmpliSeq technology on an Ion Torrent PGM platform. Deep amplicon sequencing of granulocytes DNA achieved a sample median of 1000-fold coverage. Excluding JAK2, MPL, IDH2, ASXL1 known variants, for 7 genes (SCRIB, MIR662, BARD1, TCF12, FAT4, DAP3, NRAS) we demonstrated in MPN a global mutation frequency greater than the 3%. Whereas some new variants need functional validation to prove causal mechanisms, some other mutations have a well-known pathogenic role in solid cancers but here are described for the first time in MPN. Disclosures: No relevant conflicts of interest to declare.

The Ewing sarcoma protein EWS is an RNA and DNA binding protein implicated in transcription, pre-mRNA splicing, and DNA damage response. Using CLIP-seq, we identified EWS RNA binding sites in exonic regions near 5′ splice sites. A prominent target was exon 6 of the FAS/CD95 receptor, which is alternatively spliced to generate isoforms with opposing activities in programmed cell death. Depletion and overexpression experiments showed that EWS promotes exon 6 inclusion and consequently the synthesis of the proapoptotic FAS/CD95 isoform, whereas an EWS-FLI1 fusion protein characteristic of Ewing sarcomas shows decreased activity. Biochemical analyses revealed that EWS binding promotes the recruitment of U1snRNP and U2AF65 to the splice sites flanking exon 6 and therefore exon definition. Consistent with a role for EWS in the regulation of programmed cell death, cells depleted of EWS show decreased sensitivity to FAS-induced apoptosis, and elevated EWS expression enhances apoptosis in EWS-haploinsufficient Ewing sarcoma cells. M.P.P. was supported by a fellowship from the HFSP. This project was supported by Fundación Botín, Fundación Sandra Ibarra (FSI2013), the European Union Sixth Framework Programme under grant agreement Nr. LSHG-CT-2005-518238-V (EURASNET), the Spanish Ministry of Economy and Competitiveness (grant no. CSD2009-00080, Consolider RNAREG/BFU2011-29583 / BIO2011-23920), and AIRC (Grant MFAG 11658). We also acknowledge support of the Spanish Ministry of Economy and Competitiveness, “Centro de Excelencia Severo Ochoa 2013-2017” (SEV-2012-0208)