Detection of chromosome 20q deletions in bone marrow metaphases but not peripheral blood granulocytes in patients with myeloproliferative disorders or myelodysplastic syndromes

Myeloproliferative disorders and myelodysplastic syndromes arise in multipotent progenitors and may be associated with chromosomal deletions that can be detected in peripheral blood granulocytes. We present here seven patients with myeloproliferative disorders or myelodysplastic syndromes in whom a deletion of the long arm of chromosome 20 was detectable by G-banding and/or fluorescence in situ hybridization in most or all bone marrow metaphases. However, in each case, microsatellite polymerase chain reaction (PCR) using 15 primer pairs spanning the common deleted region on 20q showed that the deletion was absent from most peripheral blood granulocytes. The human androgen receptor clonality assay was used to show that the vast majority of peripheral blood granulocytes were clonal in all four female patients. This represents the first demonstration that the 20q deletion can arise as a second event in patients with pre-existing clonal granulopoiesis. Microsatellite PCR analysis of whole bone marrow from two patients was consistent with cytogenetic studies, a result that suggests that cytogenetic analysis was not merely selecting for a minor subclone of cells carrying the deletion. Furthermore, in one patient, the deletion was present in both erythroid and granulocyte/monocyte colonies. This implies that the absence of the deletion in most peripheral blood granulocytes did not reflect lineage restriction of the progenitors carrying the deletion but may instead result from other selective influences such as preferential retention/destruction within the bone marrow of granulocytes carrying the deletion.     

Can genome array screening replace FISH as a front‐line test in multiple myeloma?

Multiple myeloma (MM) is a malignant disorder characterized by neoplastic transformation of mature B cells in the bone marrow (BM), accompanied by complex genetic changes. The disease is heterogeneous at both the clinical and genomic levels. Molecular genetics and genomic investigations have demonstrated that disease evolution is associated with an accumulation of specific aberrations, mostly genome imbalances, which not only shed light on the disease pathogenesis but also allow risk assessment and treatment monitoring. We used a catalogue version of the Agilent 8x60K oligo‐array with immuno‐magnetically isolated CD138(+) cells from BM samples of 50 patients with myeloma to evaluate the merit of array comparative genomic hybridization (aCGH) as a diagnostic tool. We demonstrate the ability of aCGH to detect clonal imbalances to a level well below established clinically significant thresholds. aCGH, combined with target enrichment and complemented with tests for IGH rearrangements offers a cost neutral alternative to multiprobe fluorescence in situ hybridization screening. While we recognize the limitations of the standard version of the 8x60k array we demonstrate the value of aCGH as a first tier test in the diagnostic workup of MM. The array technology enables high‐risk disease stratification with the added benefit of providing whole genome data to assist in establishing clinically relevant predicative markers. © 2014 Wiley Periodicals, Inc.     

A new human B-cell non-Hodgkin's lymphoma cell line (Karpas 422) exhibiting both t (14;18) and t(4;11) chromosomal translocations

A unique B-cell non-Hodgkin's lymphoma (NHL) cell line (Karpas 422), bearing both t(14;18) and t(4;11) chromosomal translocations as well as several other chromosomal abnormalities, has been established from the pleural effusion of a patient with chemotherapy-resistant NHL. This cell line has the same karyotypic features as malignant cells from the patient. The major cell clone is characterized chromosomally by 46,XX t(2;10)(p23;q22.1), t(4;11)(q21.3; q23.1), t(14;18)(q32.1;q21.3), t(4;16)(q21.3;p13.1). Both phenotypically and genotypically, the cell line has features of a mature B-cell neoplasm with no evidence for commitment to other lineages. Rearrangements of the C-ETS-1 oncogene and N-CAM-1 and CD3 genes that map to 11q23 were not detected by conventional Southern analysis. BCL-2 was rearranged within the major breakpoint cluster. The K422 cell line has a unique karyotype; this is the first occasion that the t(4;11) translocation has been described in a t(14;18) lymphoma. The cell line will be of value in determining the molecular nature of the t(4;11) translocation.     

Comparative Genomic Hybridization: A Comparison with Molecular and Cytogenetic Analysis

Comparative genomic hybridization (CGH) is a powerful technique for detecting copy number changes throughout the genome. We describe the development of a versatile image analysis program for CGH studies. Several methods for the production of metaphases which give optimum hybridization signals have also been assessed. CGH analysis was performed on DNA samples from several different and clinically relevant specimens: amniotic fluid cells trisomic for a single chromosome, lymphoblastoid cell lines with abnormalities involving single chromosome bands, malignant cell lines and biopsy material from primary ovarian carcinomas. The results were compared with those derived from G-banding, chromosome painting, and molecular genetic techniques. Our data demonstrate that CGH was able to detect a wide range of quantitative genetic alterations including duplication or deletion of single chromosome bands. CGH analysis also indicated the presence of genetic abnormalities that were not detected by other cytogenetic or molecular approaches. Moreover, our CGH methodology allowed the ready comparison of CGH results from different tumors, a process which greatly facilitated identification of shared genetic changes.