Chromosome 14q32 translocations involving the immunoglobulin heavy chain locus in chronic lymphocytic leukaemia identify a disease subset with poor prognosis.

Immunophenotypic studies, fluorescence in situ hybridization (FISH) and conventional karyotyping were used to define the clinicobiological significance of 14q32 translocations involving the immunoglobulin gene locus (14q32/IGH) in 252 chronic lymphocytic leukaemia (CLL) patients. The following regions were studied: 13q14, centromere 12, 6q21; 11q22/ATM; 17p13/TP53, 14q32/IGH. Patients were classified as group 1 (favourable, i.e. 13q-single or normal), group 2 (intermediate risk, i.e. +12, 6q-, 1-2 anomalies), group 3 (unfavourable, i.e. 17p-, 11q-, complex karyotype), or group 4 (14q32/IGH translocation). Endpoints were treatment-free survival (TFS) and overall survival (OS). One hundred and ten patients were included in group 1, 99 in group 2, 25 in group 3 and 18 in group 4. 14q32/IGH translocation partners were identified in eight cases (BCL2 in five cases, BCL11A, CCND3 and CDK6 in one case each). group 4 showed shorter TFS versus groups 2 and 1 (25% patients treated at 2 months vs. 12 (P = 0.02) and 20 months (P = 0.002), respectively) and shorter OS (25% patients dead at 18 months versus 50 (P = 0.0003) and >60 months (P < 0.0001) respectively. The 14q32/IGH translocation maintained prognostic significance at multivariate analysis on TFS (P = 0.025) and OS (P < 0.001), along with advanced stage and CD38+. These findings show that the 14q32/IGH translocation predicts for an unfavourable outcome in CLL and that this cytogenetic subset might be included as a separate entity in a hierarchical cytogenetic classification of CLL.

Genetic diagnosis by comparative genomic hybridization in adult de novo acute myelocytic leukemia.

A total of 127 adult de novo acute myelocytic leukemia (AML) patients were analyzed by comparative genomic hybridization (CGH) at diagnosis. Conventional cytogenetic analysis (CCA) showed a normal karyotype in 45 cases and an abnormal karyotype in 56 cases; in the remaining cases, CCA either failed to yield sufficient metaphase cells (19/26) or was not done (7/26). Abnormal CGH profiles were identified in 39 patients (30.7%). DNA copy number losses (61%) were high compared to gains (39%), whereas partial chromosome changes (76%) were more common than whole chromosomes changes (24%). Recurrent losses were detected on chromosomes 7, 5q (comprising bands 5q15 to 5q33), 7q (7q32 approximately q36), 16q (16q13 approximately q21), and 17p, and gains were detected on chromosomes 8, 22, and 3q (comprising bands 3q26.1 approximately q27). Furthermore, distinct amplifications were identified in chromosome regions 21q, 13q12 approximately q13, and 13q21.1. No cryptic recurrent chromosomal imbalances were identified by CGH in cases with normal karyotypes. The concordance between CGH results and CCA was 72.5%. In the remaining cases, CGH gave additional information compared to CCA (20%) and partially failed to identify the alterations previously detected by CCA (7.5%). The majority of discrepancies arose from the limitations of the CGH technique, such as insensitivity to detect unbalanced chromosomal changes when occurring in a low proportion of cells. CGH increased the detection of unbalanced chromosomal alterations and allowed precise defining of partial or uncharacterized cytogenetical abnormalities. Application of the CGH technique is thus a useful complementary diagnostic tool for CCA in de novo AML cases with abnormal karyotypes or with unsuccessful cytogenetics.