Contribution of multiparameter genetic analysis to the detection of genetic alterations in hematologic neoplasia. An evaluation of combining G-band analysis, spectral karyotyping, and multiplex reverse-transcription polymerase chain reaction (multiplex RT-PCR).

We investigated 150 acute myeloid leukemia (AML) patients and 48 acute lymphoblastic leukemia (ALL) patients by multiplex RT-PCR to 7evaluate the adjuvant diagnostic effect, vis-à-vis G-banding and spectral karyotyping (SKY), and the potentials of this method for providing means for monitoring residual disease by real-time quantitative RT-PCR. An abnormal G-banded karyotype was found in 57% of AML and 68% of ALL cases. Ninety-six patients were investigated by SKY in parallel which extended or confirmed the G-banding finding in 94/96 cases. In patients with an abnormal G-banded karyotype, classification of chromosomes involved in structural aberrations by SKY was possible in 98% of the cases and SKY extended the G-banded karyotype in 34% of cases. In 32 cases, an mRNA hybrid was detected by PCR. These cases constitute 16% of the cases investigated at diagnosis (AML: 11% and ALL: 31%). In 13 of these cases, we detected an mRNA hybrid the equivalent of which was not found by G-banding or SKY (AML: 4% and ALL: 13%). By including multiplex RT-PCR, we were able to detect abnormalities in 62% of the investigated patients as opposed to 59% by G-banding. Genetic techniques complement each other and selection of relevant and targeted primer kits for the multiplex RT-PCR assay is recommended.

Recurrent genomic imbalances in B-cell splenic marginal-zone lymphoma revealed by comparative genomic hybridization.

The cytogenetics of splenic marginal zone lymphoma (SMZL) is less well characterized than the cytogenetics of other non-Hodgkin B-cell lymphomas. The aim of this study was to address this issue by identifying characteristic copy number imbalances in SMZL, for which purpose we analyzed 20 SMZL cases by comparative genomic hybridization (CGH), adding chromosome banding and fluorescence in situ hybridization (FISH) in some cases. CGH identified copy number imbalances in 70% of the cases. Imbalances were recurrently observed for chromosomes 3 (20%), 6 (20%), 7 (25%), 12 (20%), and 14 (10%). The minimally involved regions of these chromosomes were gains of 3q25 approximately qter and 12q13 approximately q15, and loss of 6q23, 7q31, and 14q22 approximately q24. A compilation of our data with data from 3 previous SMZL CGH studies revealed a significant heterogeneity between the studies. Eleven imbalances were recurrently observed in the compiled data set, as opposed to only 5 in our data set. The most frequently observed imbalances in the 73 SMZL cases of the compiled data set were gains of 3q (27%) and 12q (15%), and loss of 7q (18%). Our data suggest that SMZL constitute a genetically heterogeneous disease where gain of 3q25 and loss of 7q31 are the most likely imbalances to be involved in the pathogenesis of the disease.