JAK2 in Ph-like B-Acute Lymphoblastic Leukemia.

OBJECTIVES: The Janus Kinase 2 gene (JAK2) provides instructions for generating a protein that promotes the division and growth, or what is referred to as the proliferation, of cells. This generated protein relays signals in cells in order to promote cell growth, as well as help manage the count of white blood cells, red blood cells, and platelets that are generated within the bone marrow. Mutations and rearrangements of JAK2 are found in 3.5% of B-acute lymphoblastic leukemia (B-ALL) cases and in 18.9% of Down syndrome B-ALL patients, and are associated with a Ph-like ALL and a poor prognosis. However, there have been great challenges in understanding their role in this pathogenesis. In this review, we will discuss the most recent literature and trends associated with JAK2 mutations in patients with B-ALL.

Molecular Cytogenetic Characterization of a Structural Abnormal Chromosome 16 in a Patient with Acute Myeloid Leukemia Leading to Inversion Chromosome 16 with Concomitant 3'CBFB Deletion.

OBJECTIVES: Acute myeloid leukemia (AML) presents as a heterogeneous blood cancer characterized by the proliferation of immature myeloid cells. We present the case of an 18-year-old female with AML whose symptoms include marked leukocytosis, anemia, as well as thrombocytopenia with spontaneous cerebellar and intracerebral bleeds. The bone marrow biopsy is hypercellular and is expunged by sheets of blast cells with dispersed chromatin, prominent nucleoli, highly irregular nuclei, and moderate cytoplasm. Chromosome analysis reveals an abnormal karyotype with a derivative trisomy 8 and a derivative chromosome 16. The karyotype is described as 47,XX,+der(8)add(8)(q24.3),der(16) inv(16)(p13.1q22)del(16)(q22)[21]/46,XX[1]. DNA FISH analysis reveals abnormalities for RUNX1T1 (8q21.3) and CBFB (16q22) genes. These findings align with that of conventional cytogenetics. The National Comprehensive Cancer Network guidelines for AML state that CBFB gene rearrangements indicate that the patient falls under the favorable risk category. However, AML with core binding factor molecular aberrations is a heterogeneous group and thus the interaction with further cytogenetic abnormalities may result in further pathogenesis. Clinical correlation was suggested.

c-MYC Amplification in AML.

OBJECTIVES: Acute myeloid leukemia (AML) is a clonal disorder of myeloid lineage precursors. Identification of cytogenetic aberrations is essential for classification and risk stratification of AML, with many demonstrating unique associations with various clinicopathologic features. One such abnormality is MYC amplification, a rare occurrence identified in less than 1% of AML patients. MYC is most commonly amplified in the form of double minutes, but may also occur via ring and marker chromosomes or homogeneously staining regions. Amplification of MYC often involves various chromosomal aberrations, including trisomies 4 and 6 and aneusomy of the sex chromosomes. In many cases, the presence of MYC amplicons is also associated with other negative prognostic factors, including complex karyotype and advanced age. Although MYC has been extensively investigated as a therapeutic target in various cancers, there are few studies examining the clinical significance of MYC amplification in AML. In this review, we explore recurrent cytogenetic abnormalities and demographic characteristics associated with amplification of MYC in patients with AML and discuss their diagnostic and therapeutic implications.

A t(9;11)(p22;q23) Within the Context of a Complex Karyotype is Associated with a Poor Prognosis in a 19-Year-Old Patient with AML.

OBJECTIVES: A 19-year-old male with a history of irritable bowel syndrome presented with progressive fatigue, periorbital petechiae, and abdominal pain for 2-3 weeks. The peripheral blood smear showed leukocytosis and circulating blasts. Elevated PT, PTT, and FDP with normal fibrinogen were found in the DIC panel workup. Abdominal CT suggested splenomegaly. A bone marrow biopsy revealed sheets of monotonous agranular monoblasts nearly completely replaced the hematopoietic elements. Chromosome analysis depicted an abnormal male karyotype with a t(9;11)(p22;q23) in all metaphase cells examined. Four cells showed, in addition, two 8q isochromosomes. FISH analysis was utilized with the MYC (8q24.21) probe from Abbott and the KMT2A (11q23), those of which showed gain on MYC and evidence of KMT2A. These findings correlate with the concurrent conventional cytogenetic findings and were described as nuc ish(MYCx4~9)[182/200],(KMT2Ax2)(5'KMT2A sep 3'KMT2Ax1)[181/200]. Complex karyotypes are associated with poor prognosis. Although only a few pediatric cases exist in the literature, the presence of additional abnormalities put this finding as a poor prognostic marker in AML. Correlation with other clinical data was indicated.

ASXL1 Gene in AML.

OBJECTIVES: The ASXL1 (additional sex combs like 1) gene on 20q11 codifies the ASXL1 protein that belongs to protein complexes that play a role in gene expression and epigenetic regulation. ASXL1 is located near the DNMT3B gene and is part of a family of three genes (ASXL1, ASXL2, ASXL3) that are homologues to the Drosophila Asx gene. The ASXL1 gene contains a total of 14 exons and is expressed in the vast majority of hematopoietic cell types. While the specific job of ASXL1 in normal hematopoiesis and the involvement of mutated ASXL1 to the progression of hematopoietic malignancies have not yet been fully set forth, current data studies propose that ASXL1 is characterized as a tumor suppressor gene. Mutations in the ASXL1 gene are observed in myeloid malignancies usually associated with aggressiveness and poor clinical results and were reported first in the year 2009 in myelodysplastic syndromes (MDS). Nevertheless, ASXL1 gene mutations are also found in acute myeloid leukemia (AML) with normal karyotype as well as AML with myelodysplasia-related changes and AML with non-characteristic cytogenetic findings. Herein we examine the involvement of the ASXL1 gene in AML to address the importance of these ASXL1 mutations in the prognostic evaluation of AML.

FLT3 Gene Involvement in B-cell Acute Lymphoblastic Leukemia (B-ALL).

OBJECTIVES: The FMS-like tyrosine kinase 3 gene (FLT3) is a receptor tyrosine kinase expressed in early hematopoietic progenitors that play an important role in hematopoietic development. The signaling pathways that are stimulated by the FLT3 protein manage several crucial cellular processes including division, growth, and survival of cells, specifically of hematopoietic progenitor cells. Activating mutations of this gene have been highly discussed in myeloid malignancies, including myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). However, FLT3 mutations are also observed in around 5% of acute lymphoblastic leukemia (ALL) patients. These mutations were usually found to be one of the four types: internal tandem duplications, tyrosine kinase domain mutations, juxtamembrane insertion and deletion, and juxtamembrane point mutation. The presence of FLT3 mutations in pediatric B-ALL patient populations tend to be associated with relapse and poor prognosis. These mutations are also correlated with poor prognosis in adult B-ALL patients. Due to the rarity of FLT3 mutations in B-ALL patients, there have been many challenges in attempts to understand their role in pathogenesis. In this review, we will discuss the most recent literature and trends associated with FLT3 mutations in B-ALL patients in order to elucidate their cytogenetic, molecular, and clinical implications.