Subject(s)
Biomarkers, Tumor/genetics , Gene Deletion , Leukemia, Myeloid, Acute/genetics , Myelodysplastic Syndromes/genetics , Proto-Oncogene Proteins c-ets/genetics , Repressor Proteins/genetics , Adult , Aged , Aged, 80 and over , Chromosome Deletion , Chromosomes, Human, Pair 7/genetics , Humans , In Situ Hybridization, Fluorescence , Leukemia, Myeloid, Acute/pathology , Middle Aged , Myelodysplastic Syndromes/pathology , Prognosis , ETS Translocation Variant 6 ProteinABSTRACT
The low proliferation rate of myeloma cells in vitro can result in a normal cytogenetic karyotype with the abnormal cell population not being detected. Because plasma cell myeloma is a patchy disease, conventional FISH is also hampered by normal cell contamination. Identification of plasma cells by cytoplasmic immunoglobulin staining in combination with FISH (cIg FISH) can ensure that only the cells of interest are analyzed, and thus the results obtained are a more accurate reflection of the plasma cell population karyotype. Current literature suggests that probes for t(4;14), t(14;16), and del(17)(p13) should be used in routine diagnostic testing; however, this technique can be used for any probes of interest. In this chapter, we present the techniques and methods used in our laboratory for the detection of abnormalities in plasma cells by cIg staining in conjunction with FISH.
Subject(s)
Chromosome Aberrations , Cytoplasm/metabolism , Immunoglobulins/metabolism , In Situ Hybridization, Fluorescence/methods , Multiple Myeloma/genetics , Multiple Myeloma/pathology , Staining and Labeling/methods , HumansABSTRACT
Gene amplification in hematologic malignancies is uncommon. When karyotyping leukemia cells, gene amplification is generally seen as double-minute (dmin) chromosomes and homogeneously staining regions (hsr). One of the more commonly amplified regions is MYC at 8q24.21, but amplification of MLL at 11q23 and regions on 9p, 19q, and elsewhere on 11q have been reported. Increased copy number of these genes has been associated with poor prognosis. Over an 11-year period, we identified 31 cases of possible gene amplification, 27 of which had enough sample material for further investigations. A total of 17 cases had dmin only, 13 cases had hsr only, and 1 case had both dmin and hsr in the karyotype. Fluorescence in situ hybridization (FISH) analysis identified amplification of MYC in 12 cases, all on dmin, and amplification of MLL in eight cases, all on hsr. Regions other than MYC and MLL were amplified in eight cases and, using multicolor FISH and multicolor banding, we identified a number of novel regions of amplification: 13q11 approximately q12.1, 15q26.1 approximately q26.3, and 17q12. We also identified one case where two different chromosomal regions were simultaneously amplified in the same cell line.
Subject(s)
Gene Amplification , Genes, myc , In Situ Hybridization, Fluorescence , Leukemia, Myeloid/genetics , Myeloid-Lymphoid Leukemia Protein/genetics , Aged , Aged, 80 and over , Chromosome Banding , Female , Histone-Lysine N-Methyltransferase , Humans , Male , Middle Aged , Proto-Oncogene Proteins/genetics , Proto-Oncogene Proteins c-myc/geneticsABSTRACT
Two acute promyelocytic leukaemia patients, treated with all-trans retinoic acid and combination chemotherapy, acquired a deletion of 11q within 12 months of diagnosis. One patient died in relapse, with both t(15;17) and del(11q) cell lines co-existing. Patient 2 remains in remission with del(11q) in 70% metaphases, despite normal marrow morphology. No deletion of the MLL gene was identified in the latter patient. The early appearance of a del(11q) is unusual, particularly without morphological evidence of myelodysplasia. We hypothesize that the del(11q) was therapy-induced but the absence of other genetic lesions has resulted in no accompanying morphological changes.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Chromosomes, Human, Pair 11 , Leukemia, Promyelocytic, Acute/drug therapy , Leukemia, Promyelocytic, Acute/genetics , Tretinoin/therapeutic use , Chromosomes, Human, Pair 15 , Chromosomes, Human, Pair 17 , Gene Deletion , Humans , In Situ Hybridization, Fluorescence , Male , Middle Aged , Translocation, GeneticABSTRACT
The onset of accelerated phase or blast crisis of chronic myelocytic leukemia (CML) is usually associated with the acquisition of new chromosome abnormalities in addition to the t(9;22)(q34;q11) that is characteristic of the chronic phase CML. We describe the cytogenetic and molecular genetic findings in two cases of myelocytic blast crisis of CML, one occurring 6 months after commencing treatment with the ABL-specific tyrosine kinase inhibitor imatinib mesylate (STI571, Glivec, or Gleevec) and the second treated with imatinib mesylate for established blast crisis. In both cases, multiple secondary cytogenetic abnormalities were observed at transformation, with homogeneously staining regions that were shown to contain BCR/ABL amplification by fluorescence in situ hybridization appearing after imatinib mesylate administration. BCR/ABL amplification is emerging as an important mechanism of acquired resistance to imatinib mesylate.
