Volume 1 • Issue 3 • 1000114 J Leuk ISSN: 2329-6917 JLU, an open access journal Open Access Case Report Ang et al., J Leuk 2013, 1:3 DOI: 10.4172/2329-6917.1000114 *Corresponding author: Jennifer Dunlap, Department of Pathology, 3181 SW Sam Jackson Park Rd, Portland, OR 97239, USA, Tel: 503-560-4126; Fax: 503- 494-6787; E-mail: dunlapj@ohsu.edu Received April 02, 2013; Accepted May 17, 2013; Published May 20, 2013 Citation: Ang D, Fan G, Traer E, Kovacsovics T, Leeborg N, et al. (2013) Utility of Multiplex Mutation Analysis in the Diagnosis of Chronic Myelomonocytic Leukemia. J Leuk 1: 114. doi:10.4172/2329-6917.1000114 Copyright: © 2013 Ang D, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract Chronic myelomonocytic leukemia (CMML) is a myeloid neoplasm characterized by both myeloproliferative and myelodysplastic features in addition to persistent peripheral blood monocytosis (>1×10 9 /L) that is required for the diagnosis. Clonal cytogenetic abnormalities are identifed in only 20%-30% of CMML patients and it can be diagnostically challenging to exclude reactive monocytosis in some cases. Several gene mutations have recently been implicated in the pathogenesis of CMML that involve tyrosine kinase-signaling pathways, transcriptional regulation, metabolism, splicing, and epigenetic regulatory mechanisms. This study was designed to assess recurrent mutations in CMML using a multiplex mass spectrometry based approach, and to determine the utility of mutation screening in CMML, particularly in cytogenetically normal cases. The Oregon Health and Science University (OHSU) surgical pathology database was searched from 2010-2012 to identify consecutive CMML cases fulflling WHO diagnostic criteria. Cytogenetic analyses and molecular studies were performed on the diagnostic bone marrow specimens. DNA extracts were screened for point mutations using a multiplex PCR panel with mass-spectroscopy read out that covers 370 point mutations across 31 genes associated with leukemia. Of the 48 CMML cases identifed in the OHSU fles, 43 had available cytogenetic studies. Of these, 10/43 cases (23%) had cytogenetic abnormalities including: trisomy 8 (n=4), trisomy 21 (n=2), deletion 7q (n=1), del 13q (n=1), complex karyotype (n=1) and t (3;3) (n=1). Of the cases with cytogenetic data, 22 had available DNA for mutation analysis, and 11 of these genotyped cases (50%) had detectable mutations in the following genes: CBL (n=3), CKIT, JAK2, KRAS (n=2), NRAS (n=3) and NPM1. Nine cases with detected mutations had normal cytogenetics. Concomitant molecular and cytogenetic abnormalities were seen in 2 cases: one case with trisomy 8 and CBL C384Y and one case with trisomy 21 and JAK2 V617F. In the 22 cases with available cytogenetic and molecular data, performing routine multiplex molecular testing in addition to cytogenetic studies in CMML patients increased the detection of genetic abnormalities from 23% (5/22) to 64% (14/22), with frequent CBL and RAS mutations in our cohort. This study confrms that gene mutations are common events in CMML, and multiplex mutation analysis can be applied in the clinical setting to assist in diagnosis and may identify actionable mutations for targeted therapy. complex karyotype), and intermediate risk (all other single or double abnormalities) [6]. However, none of these cytogenetic fndings are specifc for CMML and the overall incidence of chromosomal abnormalities is approximately 20-30% [1]. A signifcant majority of CMML cases are diagnosed without a cytogenetic abnormality to support the diagnosis or allow risk stratifcation. Several gene mutations have recently been implicated in the pathogenesis of CMML and involve tyrosine kinase-signaling pathways, transcriptional regulation, epigenetic regulatory mechanisms, and genes involved in the splicing machinery [7-15,16]. In this study, we evaluated the frequency of cytogenetic abnormalities in CMML and report our single institution experience of mutational analysis with a multiplex mass spectrometry based approach. Keywords: Chronic myelomonocytic leukemia; Clonal cytogenetic abnormalities; Multiplex mutation analysis Introduction Chronic myelomonocytic leukemia (CMML) is a clonal hematopoietic stem cell disorder characterized by both myelodysplastic and myeloproliferative features and is defned by the presence of an absolute monocytosis (>1×10 9 L -1 ) according to the 2008 World Health Organization (WHO) classifcation [1]. CMML is subclassifed as CMML-1 with <10% bone marrow and ≤ 5% peripheral blasts, and CMML-2 with 10-19% bone marrow and/or 5-19% peripheral blasts or when Auer rods are identifed. Tis subdivision has been shown to confer a prognostically signifcant survival diference, with a median survival of 20 months for CMML-1 and 15 months for CMML-2 (p<0.005) [2-4]. Te same study showed an increased cumulative risk of evolution to AML in CMML-2 (p<0.001) [4]. Tere are recurring cytogenetic abnormalities reported in CMML which include: monosomy 7, trisomy 8, complex karyotype involving ≥ 3 abnormalities, trisomy 21, isochromosome 17, deletion 5q, and deletion 20q [5]. Such et al. [6] has previously shown cytogenetic abnormalities to be prognostic in CMML [6]. Based on their survival analysis, they defned three cytogenetic risk categories: low risk (normal karyotype and loss of Y chromosome as a single anomaly), high risk (trisomy 8 alone or with one additional abnormality, abnormalities of chromosome 7 alone or with one additional abnormality and Utility of Multiplex Mutation Analysis in the Diagnosis of Chronic Myelomonocytic Leukemia Daphne Ang 1 , Guang Fan 1 , Elie Traer 3 , Tibor Kovacsovics 3 , Nicky Leeborg 1 , Marc Loriaux 1 , Andrea Warrick 2 , Carol Beadling 2,3 , Susan Olson 2,4 , Ken Gatter 1 , Rita M. Braziel 1 , Christopher L. Corless 1,2 , Richard Press 1,2 and Jennifer Dunlap 1 * 1 Department of Pathology, Oregon Health & Science University 2 Knight Cancer Institute, Oregon Health & Science University 3 Division of Hematology and Medical Oncology, Oregon Health & Science University 4 Department of Molecular and Medical Genetics, Oregon Health & Science University Journal of Leukemia J o u r n a l o f L e u k e m i a ISSN: 2329-6917