Gene Mutations In Acute Myeloid Leukemia Research Articles

Common Driver Mutations in AML: Biological Impact, Clinical Considerations, and Treatment Strategies.

Next-generation sequencing of samples from patients with acute myeloid leukemia (AML) has revealed several driver gene mutations in adult AML. However, unlike other cancers, AML is defined by relatively few mutations per patient, with a median of 4-5 depending on subtype. In this review, we will discuss the most common driver genes found in patients with AML and focus on the most clinically relevant ones that impact treatment strategies. The most common driver gene mutations in AML occur in NPM1 and FLT3, accounting for ~30% each. There are now targeted therapies being tested or already approved for these driver genes. Menin inhibitors, a novel targeted therapy that blocks the function of the menin protein, are in clinical trials for NPM1 driver gene mutant AML after relapse. A number of FLT3 inhibitors are now approved for FLT3 driver gene mutant AML in combination with chemotherapy in the frontline and also as single agent in relapse. Although mutations in IDH1/2 and TP53 only occur in around 10-20% of patients with AML each, they can affect the treatment strategy due to their association with prognosis and availability of targeted agents. While the impact of other driver gene mutations in AML is recognized, there is a lack of data on the actionable impact of those mutations.

PB1792: NGS VS PCR FOR THE DETECTION OF NPM1 GENE MUTATIONS IN ACUTE MYELOID LEUKEMIA.

Background:NPM1 gene mutations are found in 30% of acute myeloid leukemia (AML) cases. It is a reliable marker for the evaluation of therapy outcome and minimal residual disease (MRD) monitoring. The most often mutations are 4bp insertions in exon 12, affecting 2 functionally important tryptophan residues (W288 and W290) in the C-terminal region of nucleophosmin and causing a frameshift. As a result, a leucine-rich motif (L-xxx-V-xx-V-x-L) is formed, which is a signal sequence for protein export from the nucleus to the cytoplasm. Commonly NPM1 gene mutations are detected by fragment analysis (FA) of PCR fragment of 12 exon for the presence of 4bp insert. Alternatively, allele-specific polymerase chain reaction (AS-PCR) to detect inserts belonging to the A, B, or D type (representing up to 90% of all inserts) is used. However, about 10% remaining cases are non-standard inserts and intron polymorphisms that require more precise evaluation. Aims: Evaluation of diverse approaches for efficient NPM1 gene mutation analysis and their robustness for the diagnostics. Methods: The study included 80 DNA samples from AML patients admitted to the National Research Center for Hematology in 2019-2021 that were positive for NPM1 gene mutations detected by FA performed with the Nanophor-5 genetic analyzer (Synthol, Russia). The type of insert was assessed by AC-PCR. Samples in doubt were evaluated by targeted next-generation sequencing (NGS) on MySeq (Illumina, USA). Results: In 62 out of 80 samples, the type of insert (A, B, or D) was reliably determined by AS-PCR. In 9 cases type of insert was not detected. In further 9 cases, amplification ΔCt between wild-type and mutant allele was out of reliable range. These 18 samples were examined by NGS, and 2 out of 18 showed an intron deletion, which, presumably, does not affect the function of the protein, but leads to the appearance of an additional peak on FA. In 16 out of 18 samples, non-standard inserts were detected (Table 1). Type A inserts were found in 48 out of 78 cases (61.5%), type B - in 2 out of 78 (4.5%), and type D - 15.4% (12 out of 78). We have detected atypical inserts in 16 out of 78 cases (20.5%), which is more than reported in the literature. 14 out of 16 atypical inserts result in a leucine-rich motif, as do standard inserts. In 4 out of 16 cases, one of the 2 functionally important tryptophan residues was retained (W280), therefore possibly conserving nuclear localization signal. The effect of partial preservation of the nucleolar localization of nucleophosmin on prognosis in AML has not been studied yet. Image:Summary/Conclusion: FA is still a golden standard for screening NPM1 gene mutations in AML. AS-PCR could be effectively used for monitoring cases with standard inserts. However, NGS greatly facilitates non-standard inserts identification, appropriate allele-specific primers design for MRD analysis, and avoiding false-positive FA results for cases with intron localization of the insert.

Research Advance of Gene Mutation and Targeted Drug Therapy in Childhood Acute Myeloid Leukemia --Review

The clinical therapeutic regimen for acute myeloid leukemia (AML) is not significantly different between adults and children, which is mostly based on IA (idarubicin and cytosine arabinoside) induction chemotherapy. With the rapid development of sequencing technique, people's understandings towards the molecular and biological abnormalities of AML are increasing, diverse AML gene mutation-based targeted drugs have been rapidly developed and applied. In this review, several commonly gene mutations in AML (such as FLT3, NPM1 and C/EBPA) was described, and the therapeutic effects and differences of targeted drugs that used in clinical treatment or had been reported (like tyrosine kinase inhibitor, IDH1 mutation inhibitor and epigenetic modification inhibitor) in child and adult AML patients were summrized.

PF247 CONSEQUENCES OF NRAS MUTATIONS IN PATIENTS WITH ACUTE MYELOID LEUKEMIA

Background:Acute myeloid leukemia (AML) is a malignancy with a high prevalence of NRAS mutations. Transforming point mutations, located dominantly at hotspot codons 12, 13 and 61 of NRAS gene, occur in 11 to 22% of patients. Mutations in NRAS gene stimulate signalling activity of RAS pathway, resulting in an increased cellular proliferation and reduced apoptosis. Prognostic significance of NRAS gene mutations in AML patients remains controversial.Aims:The aim of our work was to analyze the association of NRAS gene mutations in AML with patient characteristics and outcomes.Methods:A total of 297 consecutive AML (non‐acute promyelocyte leukemia) patients (median age 53 years; range 19–70) with curative therapy were analyzed by next generation sequencing (NGS) using ClearSeq AML panel (Agilent Technologies) on MiSeq and NextSeq (Illumina). The NRAS mutations detected by NGS with variant allele frequency (VAF) ≥1.0% were verified by NRAS StripAssay (ViennaLab). Only mutations scored as positive by both methods were included in further analyses. Overall survival (OS) was analyzed by log‐rank (Mantel‐Cox) test. The comparative statistical analyses were evaluated by t‐test and Fisher's exact test.Results:In total, 84 mutations were identified in 66/297 (22.2%) analyzed AML patients. Fifteen patients (22.7%) were carriers of multiple gene mutations (range 1–3 mutations per patient). The mutations were most frequently found in the codon G12 (44/84 mutations, 52.4%), the most frequent gene mutations were: G12D (26/84; 31.0% mutations), G13D (15/84; 17.9%) and G12S (14/84; 16.7%). Furthermore, rare mutation G60E was identified in one patient. The median VAF of NRAS mutations was 7.0% (range 1.0–53.4%). Frequency of co‐mutation with FLT3‐TKD reached statistical significance (p = 0.025) and a trend for co‐mutation with NPM1 (p = 0.082) and DNMT3A (p = 0.091). A trend for mutual exclusivity was observed for FLT3‐ITD mutations with allelic ratio above 0.5 (p = 0.063). Occurrence of NRAS mutations was associated with younger age (median 48 vs. 54 years, respectively, p = 0.012), and a trend towards higher white blood cell count (median 41.0 vs. 14.2, respectively, p = 0.069). There was no association with OS, blast percentage in BM or sex. The presence of multiple NRAS mutations was not associated with analyzed characteristics nor patient outcomes.Summary/Conclusion:Our study showed NRAS gene mutations detected by two independent methods in more than one fifth of AML patients with curative therapy. Most of them have low VAF, therefore suggesting their later occurrence during leukemogenesis and limited proliferative potential. Although approximately 5% of AML patients harbor multiple NRAS mutations, we were not able to identify the difference between patients with one or more NRAS mutations.Supported by Ministry of Health of the Czech Republic, grant nr. 15–25809A, project FNBr. 65269705 and project MUNI/A/1105/2018. All rights reserved.

Gene mutations in acute myeloid leukemia.

Acute myeloid leukemia (AML) is a heterogeneous disease, the onset of which involves a variety of chromosomal abnormalities and gene mutations. In recent years, the use of next-generation sequencers has facilitated intensive exploration of gene mutations resulting in the discovery of many AML-related gene mutations, and in clarifying the clonal evolution process of relapse. Epigenetic regulatory gene mutations have occurred in pre-leukemic cells with normal differentiation potential, and the acquisition of numerous genetic mutations was found to be strongly associated with AML onset, with further co-mutations contributing to clonal diversity and leading to the generation of treatment-resistant clones. As a result of these fruitful findings, the gene mutations of AML are becoming useful as not only prognostic factors but also the targets of molecular medicines such as FLT3 and IDH inhibitors. Most notably, several guidelines have proposed a prognostic classification that groups FLT3ITD, NPM1 mutation, and CEBPA mutation together under conventional chromosomal aberrations. This review outlines recent findings pertaining to the gene mutations in AML.

Clonal Evolution in NPM1 Mutated Acute Myeloid Leukemia (AML)

Background: Mutations in the nucleophosmin (NPM1) gene represent one of the most common gene mutations in AML, and are considered a founder event in the pathogenesis of AML. Recently, we gained novel insights into clonal architecture and clonal evolution in 53 NPM1 mutated (NPM1mut) AML patients (pts). Here, we showed the highest stability for DNMT3A mutations (DNMT3Amut) suggesting that these mutations represent an early event in leukemogenesis as well as an increase in genomic complexity.Aims: To validate our previous results on clonal evolution in a larger cohort of NPM1mut AML pts and to define relapse specific mutation patterns.Methods: Paired samples at diagnosis and relapse from 129 NPM1mut AML pts were assessed for additional mutations by comprehensive mutation analysis (FLT3-ITD, FLT3-TKD, DNMT3A, IDH1/2, NRAS, ASXL1, TP53, MLL-PTD). In addition, 11 AML cases with loss of NPM1mut at the time of relapse and 12 cases with persisting NPM1mut were subjected to whole exome sequencing (WES).Results: At diagnosis, the incidence of concurrent gene mutations was as follows: FLT3-ITDmut 32% (40/126), FLT3-TKDmut 19% (22/118), DNMT3Amut 69% (78/113), NRASmut 19% (22/117), IDH1mut 21% (26/123) and IDH2mut 19% (22/118). None of the pts analyzed exhibited a TP53 (n=53), MLL-PTD (n=63) or ASXL1 (n=59) mutation. At relapse, a significant shift in the genetic pattern was found in 74 pts (57%). FLT3-ITDmut was lost in 10 pts and newly acquired in 24 pts,16 pts lost FLT3-TKDmut. DNMT3Amut was lost in 2 pts and gained in 1 pt. NRASmut was lost in 12 pts and gained in 4 pts. IDH1mut was lost in 3 pts and acquired in 4 pts, while IDH2mut was lost in 2 pts and gained in only one pt. ASXL1mut and TP53mut were gained in 2 and 1 pts, respectively; gain of MLL -PTDmut (n=4) was restricted to pts with loss of NPM1mut at the time of relapse. Based on these findings we calculated the following stabilities: FLT3-ITDmut 75%, FLT3-TKDmut 27%, DNMT3Amut 97%, NRASmut 45%, IDH1mut 88% and IDH2mut 91%, respectively. In total, 11 pts (9%) lost NPM1mut at relapse while DNMT3Amut was present in 9/11 pts at diagnosis and remained stable at relapse; 4/11 pts gained MLL-PTDmut, one pt ASXL1mut and 3 pts acquired RUNX1mut.By WES we observed a persistence of mutations known to be involved in clonal hematopoiesis, such as DNMT3A and TET2 mutations. These were usually seen during all analyzed time points (diagnosis, remission and relapse). In addition, we found distinct mutational patterns at the time of relapse compared to the time of diagnosis. For example, relapse- and diagnosis-specific mutations in NPM1mut loss cases were significantly enriched for different signaling pathways.Conclusions: 74 (57%) of 129 NPM1mut AML pts showed clonal evolution at the time of relapse. DNMT3Amut demonstrated the highest stability (97%) confirming our previous findings that DNMT3Amut constitutes an early event which persists in preleukemic hematopoietic stem cells. High-resolution sequencing of selected cases is ongoing and will further unravel the clonal hierarchy in NPM1mut AML.Those authors equally contributed to work: SKS, SC, LB and KD. DisclosuresHeuser:Karyopharm: Research Funding.

Pathology Consultation on Gene Mutations in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a rapidly fatal disease without the use of aggressive chemotherapy regimens. Cytogenetic and molecular studies are commonly used to classify types of AML based on prognosis, as well as to determine therapeutic regimens. Although there are several AML classifications determined by particular translocations, cytogenetically normal AML represents a molecularly, as well as clinically, heterogeneous group of diseases. Laboratory evaluation of AML will become increasingly important as new mutations with both prognostic and therapeutic implications are being recognized. Moreover, because many patients with AML are being treated more effectively, these mutations may become increasingly useful as markers of minimal residual disease, which can be interpreted in an individualized approach. Current laboratory studies of gene mutations in AML include analysis of NPM1, FLT3, CEBPA, and KIT. In addition to these genes, many other genes are emerging as potentially useful in determining patients' prognosis, therapy, and disease course. This article briefly reviews the current most clinically relevant gene mutations and their clinical and immunophenotypic features, prognostic information, and methods used for detection.

The Impact of Molecular Genetic in Acute Myeloid Leukemias

The discovery and application of advanced molecular techniques, such as gene and microRNA expression profiling, whole genome and exome sequencing and methylation assays, allowed for the identification of recurrent molecular abnormalities in acute myeloid leukemia (AML) that have revolutionized our understanding of the genetic landscape of the disease. Moreover, these modalities have emerged as valuable tools that permit a more comprehensive and detailed molecular characterization of AML, helping in the prediction of prognosis, particularly within the context of cytogenetically normal AML (CN-AML). This review will discuss the major techniques and platforms that have been used to identify novel recurrent gene mutations in AML and briefly describe how these discoveries have impacted on outcome prediction.

The Use of Molecular Genetics to Refine Prognosis in Acute Myeloid Leukemia

The discovery and application of advanced molecular techniques, such as gene and microRNA expression profiling, whole genome and exome sequencing, proteomic analysis and methylation assays, have allowed for the identification of recurrent molecular abnormalities in acute myeloid leukemia (AML) that have revolutionized our understanding of the genetic landscape of the disease. These modalities have emerged as valuable tools that permit a more comprehensive and detailed molecular characterization of AML. Many of these molecular abnormalities have been shown to predict prognosis, particularly within the context of cytogenetically normal AML. This review will discuss the major techniques and platforms that have been used to identify novel recurrent gene mutations in AML and briefly describe how these discoveries have impacted on outcome prediction.

U2AF1 Mutations in Chinese Patients with Acute Myeloid Leukemia and Myelodysplastic Syndrome

Somatic mutations of U2AF1 gene have recently been identified in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). In this study, we analyzed the frequency and clinical impact of U2AF1 mutations in a cohort of 452 Chinese patients with myeloid neoplasms. Mutations in U2AF1 were found in 2.5% (7/275) of AML and 6.3% (6/96) of MDS patients, but in none of 81 CML. All mutations were heterozygous missense mutations affecting codon S34 or Q157. There was no significant association of U2AF1 mutation with blood parameters, FAB subtypes, karyotypes and other gene mutations in AML. The overall survival (OS) of AML patients with U2AF1 mutation (median 3 months) was shorter than those without mutation (median 7 months) (P = 0.035). No difference in the OS was observed between MDS patients with and without U2AF1 mutations. Our data show that U2AF1 mutation is a recurrent event at a low frequency in AML and MDS.

Gene Mutations in Paired Initial Presentation and Relapse Samples From Acute Myeloid Leukemia Patients,

Abstract 3592 Introductions:Gene mutationswere found in acute myeloid leukemia (AML) and their importance has been noted. Flt3, NPM1 and CEBPA were detected in “intermediate cytogenetic risk” group, and are becoming possible to distinguish subsets of patients with different outcomes. Moreover, several groups have reported that these mutations would be useful for not only predictive markers, but also minimal residual disease (MRD) markers in AML. Several recent studiesprovided compelling evidence that mutations in epigenetics modifying genes contribute to AML pathogenesis. DNMT3a mutations were common (about 20% frequency) in de novo AML and associated with poor prognosis. Furthermore, mutations of IDH1/2 and TET2 that also seem to be collaborating on DNA methylation modifying are detected, too.To clarify the importance and dynamics of these mutations in clinical course, we examined Flt3, NPM1, CEBPA, DNMT3a and IDH1/2 gene mutations in paired samples at initial presentation and relapse of AML patients. Materials and Methods:We analyzed the samples from adultpatients with de novo AML diagnosed at Nippon Medical School Hospital from 2000 to 2010. Mutation analyses were performed for Flt3 ITD by PCR amplification, Flt3 TKD by PCR-RFLP, and NPM1, CEBPA, IDH1/2 and DNMT3a mutations by direct sequence. Results:The 31 AML patients were enrolled. In chromosomal analysis at initial presentation, 19 with normal karyotype (NK-) AML, 2 with trisomy8, 4 with 11q23 associated, 1 with monosomy7, 2 with complex karyotypes and 3 with non-specific aberrations were observed. 15 cases were comparable for paired samples at diagnosis and relapse. 13 of them (86.7%) showed additional chromosomal aberrations at relapse.Gene mutations were detected more frequently in cytogenetic intermediate risk group (83.3%) than poor risk group (0%). There were 11 patients with Flt3 ITD at initial presentation, but 3 of them had no detectable mutation at relapse. Flt3 TKD were found in 3 patients at initial presentation, but all of them were lost at relapse. Among 12 patients with NPM1 mutation at initial presentation, 3 of them lost their mutation at relapse. CEBPA mutation was detected in only one paired sample at diagnosis and relapse. DNMT3a mutations were detected in 8 patients both at initial presentation and relapse. IDH2 mutations were detected in two patients at initial presentation, but 1 of them was lost at relapse. In summary, of the 37 gene mutations at initial presentation, 10 gene mutations were lost at relapse, and only 1 acquired gene mutation was detected at relapse. Flt3 ITD, NPM1, DNMT3a and IDH2 mutations frequently coexisted with another mutation. Discussion:This study is the first report of consecutive analyses on the major gene mutations in AML. Newly acquired gene mutations at relapse are rare compared to frequent additional chromosomal aberrations at relapse.Flt3 ITD mutations at initial presentation were detected also at relapse. This finding indicates that Flt3 ITD are responsible for relapse and refractoriness. On the other hand, all 3 cases with Flt3 TKD lost the mutation at relapse, suggesting that Flt3 TKD mutation does not contribute to their relapse.Some of Flt3 ITD, Flt3 TKD and NPM1 mutations could not be detected at relapse, indicating that these mutations should be used carefully for MRD marker. DNMT3a mutations were detected both at diagnosis and relapse in all 8 cases. This finding suggests that DNMT3a mutations might be a useful MRD marker. Disclosures:No relevant conflicts of interest to declare.

Current findings for recurring mutations in acute myeloid leukemia

The development of acute myeloid leukemia (AML) is a multistep process that requires at least two genetic abnormalities for the development of the disease. The identification of genetic mutations in AML has greatly advanced our understanding of leukemogenesis. Recently, the use of novel technologies, such as massively parallel DNA sequencing or high-resolution single-nucleotide polymorphism arrays, has allowed the identification of several novel recurrent gene mutations in AML. The aim of this review is to summarize the current findings for the identification of these gene mutations (Dnmt, TET2, IDH1/2, NPM1, ASXL1, etc.), most of which are frequently found in cytogenetically normal AML. The cooperative interactions of these molecular aberrations and their interactions with class I/II mutations are presented. The prognostic and predictive significances of these aberrations are also reviewed.

High-Resolution Comparative Genomic Hybridization of Mirna Genes In Therapy-Related AML Identifies a Somatic Deletion of MiR-223

AbstractAbstract 2759MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression and diverse cellular processes. Expression profiling of miRNAs has identified dysregulated miRNAs in many cancers, including acute myeloid leukemia (AML). However, the mechanism for altered miRNA gene expression and the frequency of miRNA gene mutations in AML is largely unknown. We performed next-generation sequencing and high-resolution comparative genomic hybridization (CGH) to determine the frequency of miRNA gene mutations in 30 patients with therapy-related AML (t-AML). The sequencing is completed, and final analysis is underway. Herein, we report the results of the CGH. We designed custom CGH arrays for all 835 miRNA genes in miRBase (version 14) and 44 genes involved in miRNA processing. Average probe spacing was 30 bp for miRNA genes and 80 bp for miRNA processing genes and 10 kb flanking regions were interrogated for all genes. In each case, genomic DNA from leukemic blasts was compared with DNA from a skin biopsy from that patient. The median age of the 30 patients with t-AML was 49.2 years (25-77) with M:F ratio 13:17. The mean blast % was 81% (31-100). Consistent with previous reports, many of these patients had an abnormal karyotype with abnormalities of chromosome 5 and 7, 13% and 17% respectively. As expected, CGH analysis confirmed copy number alterations already identified by cytogenetics. In addition, we identified a single t-AML sample (from a male patient) that carried a small (435 kb) hemizygous deletion of miR-223 on chromosome × that was not apparent by cytogenetics. Quantitative PCR of genomic DNA confirmed the loss of the miR-223 gene, and real time RT-PCR demonstrated loss of miR-223 expression. Of note, miR-223 has been implicated in the regulation of granulopoiesis, and mice lacking miR-223 display a myeloproliferative phenotype (Johnnidis, Nature 2008). We screened an additional 27 AML patients for miR-223 expression and identified 3 other samples with miR-223 expression 2 standard deviations below the normal (based on CD34+ cells from healthy donors). No copy number alterations in miR-223 were detected in these patients, suggesting epigenetic silencing of miR-223. Consistent with this possibility, one of these patients carried a t(8;21), which has been shown to epigenetically silence miR-223 (Fazi, Cancer Cell 2007). The mechanism by which miR-223 is silenced in the other two AML samples is under investigation. In summary, cytogenetically silent deletions of miRNA genes are uncommon in t-AML. Loss of miR-223 expression can occur through somatic mutation or epigenetic silencing and is likely to contribute to leukemic transformation in a subset of patients with AML. Disclosures:No relevant conflicts of interest to declare.

Next Generation Sequencing Based Identification of Translocations In Clinical Acute Myeloid Leukemia Specimens

AbstractAbstract 581 Introduction:Acute Myeloid Leukemia (AML) is currently subclassified based on the presence of recurrent cytogenetic abnormalities. The 2008 WHO guidelines recognize seven such translocation events: t(8;21)(q22;q22), inv(16)(p13.1;q22), t(15;17)(q22;q12), t(9;11)(p22;q23), t(6;9)(p23;q34), inv(3)(q21q26.2), t(1;22)(p13;q13). Current clinical methods for the detection of translocations rely on low-resolution techniques such as conventional cytogenetics or fluorescence in-situ hybridization (FISH). Although FISH offers higher resolution compared with conventional cytogenetics, FISH is unable to detect novel translocation partners since break-apart probes detect only gene rearrangements of the target loci; this limitation is particularly problematic for genes known to undergo rearrangement with numerous partners, including the mixed myeloid leukemia gene (MLL) on 11q23 that is disrupted in up to 12% of AMLs and has over 80 known translocation partners. Here we describe a novel method based on hybrid capture enrichment, next generation sequencing, and bioinformatic analysis for identifying prognostically-significant translocations and gene mutations in AML. Methods:Biotinylated RNA capture probes were designed to 2X tile across introns and exons of all currently known genes implicated in AML risk assessment (table 1) for a total target region of 1.0Mb. Approximately 5μ g of patient genomic DNA, extracted from bone marrow samples of patients with AML and known recurrent cytogenetic abnormalities, was ligated with Illumina sequencing adapters, hybridized to the capture probes and enriched by the application of streptavidin-coated magnetic beads. Captured DNA was then eluted, amplified, and sequenced on an Illumina GAII genome analyzer using 60bp paired-end reads. The resulting paired-end reads were then aligned using MAQ to gene regions targeted by the capture probes. Aligned data were then used to identify chimeric single-end reads representing actual translocation boundaries via the SLOPE software package. These putative translocation sites were then validated by examining sequence pairs in which each of the two reads mapped near the chimeric sequence to construct contigs spanning the translocation boundaries. The contigs were aligned to build37 of the human genome to determine the identity and location of translocation partners. Results:As a proof of principle, we extracted DNA from the bone marrow of a patient with AML and a t(9:11) translocation detected by conventional cytogenetics. Approximately 18% of the sequence reads (9,302,232 reads) mapped to the regions targeted by the capture probes, with an average coverage of 1,100 fold. Without a priori knowledge of the actual translocation breakpoint, we identified a single MLLT3-MLL translocation (ch9:20345470-20345657; ch11:118,354,278-118,354,440 involving intron 9 of MLL and intron 7 of MLLT3). There was no evidence of mutations in other relevant genes targeted by the capture probes, including FLT3, NPM1, or CEBPA. Conclusion:We present a novel method for detection of prognostically-significant translocations in clinical AML specimens with single-base resolution, regardless of the translocation partner. While molecular methods such as inverse PCR, ligation-mediated PCR, and panhandle PCR are also capable of identifying translocations with single-base resolution, they are technically complex, time consuming, and generally not well-suited to clinical laboratory applications. By combining numerous capture probes spanning all currently known genes implicated in AML risk assessment in a single assay, the method has the capability of replacing multiple test methodologies including FISH, PCR, and Sanger sequencing. Compared with clinical full-genome sequencing, our targeted approach offers decreased cost, quicker turn-around time, and much simplified bioinformatic analysis. Furthermore, given the high sequence coverage, it will be possible to multiplex samples from different patients in a single assay, further reducing the cost of testing.Table 1Targeted Capture RegionsGenes involved in translocationsLocationMutated GenesLocationRUNX112q22.12CEBPA19q13.1CBFB16p13.1NPMN5q35RARA17q12c-kit4q11MLL11q23FLT313q12NUP2149q34GATA1Xp11.23EVI13q26.2NOTCH19q32MKL122q13KRAS12p12.1ABL9q11.2IDH12q33IL35q31LMO211p13E2A19p13.3TAL11p32 Disclosures:Armstrong:Cofactor Genomics: Employment.