Interstitial telomere repeats in translocations of hematopoietic disorders.

Cytogenetic and fluorescence in situ hybridization studies have shown the presence of telomeric repeats in translocation present in three patients with hematopoietic malignancies. One had jumping translocations, involving 1q12 and 2q, 16p, and 19q. These sequences were detected by FISH only in derivative chromosomes t(1;16) and t(1;19) in the first patient, and t(1;7) in the second. They were not seen in derivative t(1;2) and t(7;8), respectively. Interstitial telomeric sequences were observed in der(2)t(1;2) in about half of the metaphases in the third patient. The instability of interstitial telomeric DNA repeats in translocations is shown by the present findings. Moreover it supports the hypothesis that the presence of interstitial telomere repeats is not sufficient to make it functional.

Chromosomal analysis in multiple myeloma: cytogenetic evidence of two different diseases.

We report the cytogenetic results obtained in 81 multiple myeloma (MM) patients with abnormal karyotypes. Most karyotypes were complex with numerical and structural abnormalities but the analysis of chromosomal abnormalities allowed identification of two cytogenetic patterns depending on the chromosome number: a first hyperdiploid pattern (54%) with recurrent trisomies 3, 5, 7, 9, 11, 15 and 19 and a second pattern (46%) showing either pseudodiploid, hypodiploid or near-tetraploid karyotypes. Structural abnormalities were present in all but five hyperdiploid karyotypes, and frequently involved lymphoid breakpoints: immunoglobulin gene regions (36 cases) or chromosome 11q13 region (21 cases). Numerous other structural aberrations were detected; the most frequent involved chromosome 1 and chromosome 13. Structural abnormalities were significantly more frequent in the second hypodiploid group. When analyzing the results obtained in the 60 patients studied at the time of diagnosis, a prognostic correlation was found between the cytogenetic pattern and overall survival: hyperdiploid patients had a longer survival than patients belonging to the pseudo/hypo/near-tetraploid group (median survival 36.8 vs 18.2 months, P < 0.04). These results suggest that MM could correspond to two closely related diseases.

[Contribution of a hematologic cytogenetic laboratory to the diagnosis, classification and prognosis of various hematologic malignancies]. / Contribution d'un laboratoire de cytogénétique en hématologie, au diagnostic, à la classification et au pronostic de certaines hémopathies malignes.

The presence of an haematological cytogenetic laboratory into a clinical unit allowed to realize a close collaboration between clinicians and cytogeneticists, and to achieve a maximal exploitation of the results of the bone marrow cytogenetic studies in some haematological malignancies. It made it possible to perform sequential bone marrow karyotypes studies during the different phases of a disease: We could thus establish: The diagnostic value of cytogenetic findings for chronic myelocytic leukaemia, secondary acute leukaemia, but not for dysglobulinemias. The prognostic value of cytogenetic abnormalities in chronic myelocytic leukaemia where additional abnormalities to the Ph1 are a hallmark of blastic transformation; in primitive dysmyelopoiesis where they represent a bad prognostic factor; in dysglobulinemias, where they are a signal of terminal evolution. In all these diseases, only complex and multiple abnormalities have a prognostic significance pointing out the emergence of a malignant clone, where as rare and single abnormalities are of no significance. Nowadays, haematological cytogenetic must be bound to molecular biology.

Hypodiploidy is a major prognostic factor in multiple myeloma.

Conventional karyotypes performed before any treatment in 208 patients with multiple myeloma were reviewed by the Groupe Français de Cytogénétique Hématologique. A total of 138 patients displayed complex chromosomal abnormalities (CCAs). According to the chromosome number pattern, a first group of 75 patients had a hyperdiploid karyotype. A second group of 63 patients referred to as the hypodiploid group had either pseudodiploid, hypodiploid, or near-tetraploid karyotypes. Of 159 treated patients available for survival analysis, 116 had an abnormal karyotype. The comparison of overall survival (OS) between hyperdiploid and hypodiploid patients showed a highly significant difference (median OS 33.8 vs 12.6 months, respectively, P <.001). The presence of 14q32 rearrangements (36 of 116 patients) worsened the prognosis (median OS 17.6 vs 29.9 months, P <.02). The presence of chromosome 13q abnormalities (13qA, 63 patients) did not modify OS in CCA patients (median OS 20.6 vs 27.8 months, P <.59). However, taking into account the whole series including normal karyotypes, 13qA (63 of 159 patients) had a significant impact on OS (median 20.6 vs 37.1 months, P <.04). In the same way, the presence of a hypodiploid karyotype (52 of 159 patients) had a strong prognostic value (OS 12.8 vs 44.5 months, P <.000 01). A multivariate analysis including stage, beta2-microglobulin, bone marrow plasmocytosis, treatment type, 13qA, and hyperdiploidy and hypodiploidy showed that a hypodiploid karyotype was the first independent factor for OS (P <.001), followed by treatment approach. These results confirm that the chromosome number pattern of malignant plasma cells is a very powerful prognostic factor in newly diagnosed multiple myeloma patients.

Cytogenetic study in multiple myeloma at diagnosis: comparison of two techniques.

Cytogenetic studies in multiple myeloma (MM) have been disappointing due to the low mitotic index of plasma cells. Recently the detection of clonal chromosomal abnormalities at diagnosis seemed to be improved by addition of cytokines (IL-6 and GM-CSF) in the culture medium. We performed two parallel total bone marrow cells culture types in 33 stage I, II and III multiple myeloma patients at diagnosis: 3 d without any cytokine, and 4-7 days stimulated with IL-6 and GM-CSF. No clonal chromosomal abnormality was detected in the 12 stage I and II patients either in 3 d or in 4-7 d culture. In stage II patients, abnormalities were observed in 18/21 (85.7%) and in 8/18 (44.4%) in the 3 d culture and the 4-7 d stimulated cultures respectively. Our results suggest that in stage III multiple myeloma at diagnosis, 3 d culture without cytokine may be the better technique to detect clonal chromosomal abnormalities, and, before using cytokines as a reference condition, this 3 d unstimulated culture should be considered.