API2/MALT1 translocation, t(11;18) (q21;q21) In gastric MALT lymphoma 1/3 or less of cases have been reported to carry the t(11;18) API2-MALT1 translocation. This translocation is usually indicative of unresponsiveness to Helicobacter pylori eradication and is present in advanced disease states.
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CEBPA mutations CCAAT/enhancer binding protein α (CEBP/α) is a leucine zipper transcription factor with a pivotal role in myeloid differentiation. Mutations in the CEBPA gene have been described in approximately 10% of patients with AML, in particular those with intermediate-risk karyotypes. They can occur across the whole gene but cluster in two main hotspots. AML with mutated CEBPA
NPM1 mutation The NPM1 mutation or its immunohistochemical surrogate (cytoplasmic nucleophosmin) appears to be restricted to AML and is usually expressed in the whole leukemic population. In patients with acute myeloid leukemia (AML) and intermediate-risk cytogenetics, nucleophosmin-1 (NPM1) mutation status and internal tandem duplication of FLT3 gene (FLT3-ITD) can assist in predicting a patient’s risk of relapse
FLT3 mutations Mutations in the fms-like tyrosine kinase-3 gene (FLT3) gene are common in AML and are present in approximately 30% of diagnoses. The most common abnormality in FLT3 (23-34%) are internal tandem duplication (FLT3-ITD). FLT3-ITD encodes an abnormal protein that induces dimerization and constitutive activation of STAT5, JAK2 and MAPK pathways leading to increased
IGH/FGFR3 translocation, t(4;14)(p16;q32) The t(4;14) translocation is associated with upregulation of the fibroblast growth factor receptor 3 (FGFR3) and the myeloma SET domain protein. This reciprocal translocation is a common alteration in multiple myeloma (MM) not often detected by classic cytogenetics, because of the telomeric location of the regions involved. Patients with t(4;14) demonstrate an
Loss of ATM gene, del(11q22.3) The protein kinase ATM (Ataxia-Telangiectasia Mutated) gene located in 11q22.3 is frequently deleted in cases of CLL. The ATM gene is an important checkpoint gene involved in cell damage management. Its function is to assess the level of DNA damage that the cell has received and attempt to repair the DNA
IGH/MYC translocation, t(8;14) Translocation t(8;14)(q24;q32), IGH-MYC, is the cytogenetic hallmark of Burkitt’s lymphoma, but also found in rare occasions, in cases of B-cell lymphoma or chronic lymphocytic leukemia (CLL). This translocation results in a fusion gene that deregulates and overexpressee MYC. FISH is very useful in understanding these complex chromosomal abnormalities and their relationship to other
IGH rearrangements, (14q32) There are a number of stereotypical translocations involved in IGH (14q32) rearrangements associated with lymphoblastic leukemias. In B-ALL, IGH is most notably involved in rearrangements involving the cMYC oncogene as a result of the t(8;14) translocation. However, less common rearrangements of the IGH gene are most often seen in T-ALL, but can also be found in B-ALL (0.1% of the
TCF3-PBX1 fusion gene, t(1;19) t(1;19)(q23;p13) translocation event between the TCF3 locus (19p13.3) and PBX1 locus (1q23) which produces the chimeric gene TCF3-PBX1, is present in most type L1 and type L2 ALLs and exceptionally in ALL- L3. The translocation occurs in approximately 5% of childhood ALL and while this chromosomal anomaly usually was associated with poor prognosis, nowadays associates with
ABL-BCR translocation, t(9;22) The t(9;22)(q34;q11.2) translocation fuses ABL proto-oncogene on chromosome 9 with the BCR (breakpoint cluster region) region located on chromosome 22, leading to the formation of the Philadelphia chromosome (Ph) and the formation of two hybrid genes. The first gene is BCR-ABL (major), located on the long arm of chromosome 22 or chromosome
