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Immunoglobulin gene translocations in chronic lymphocytic leukemia: A report of 35 patients and review of the literature.

ABSTRACT: Chronic lymphocytic leukemia (CLL) represents the most common hematological malignancy in Western countries, with a highly heterogeneous clinical course and prognosis. Translocations involving the immunoglobulin (IG) genes are regularly identified. From 2000 to 2014, we identified an IG gene translocation in 18 of the 396 patients investigated at diagnosis (4.6%) and in 17 of the 275 analyzed during follow-up (6.2%). A total of 4 patients in whom the IG translocation was identified at follow-up did not carry the translocation at diagnosis. The IG heavy locus (IGH) was involved in 27 translocations (77.1%), the IG ? locus (IGK) in 1 (2.9%) and the IG ? locus (IGL) in 7 (20.0%). The chromosome band partners of the IG translocations were 18q21 in 16 cases (45.7%), 11q13 and 19q13 in 4 cases each (11.4% each), 8q24 in 3 cases (8.6%), 7q21 in 2 cases (5.7%), whereas 6 other bands were involved once (2.9% each). At present, 35 partner chromosomal bands have been described, but the partner gene has solely been identified in 10 translocations. CLL associated with IG gene translocations is characterized by atypical cell morphology, including plasmacytoid characteristics, and the propensity of being enriched in prolymphocytes. The IG heavy chain variable region (IGHV) mutational status varies between translocations, those with unmutated IGHV presumably involving cells at an earlier stage of B-cell lineage. All the partner genes thus far identified are involved in the control of cell proliferation and/or apoptosis. The translocated partner gene becomes transcriptionally deregulated as a consequence of its transposition into the IG locus. With the exception of t(14;18)(q32;q21) and its variants, prognosis appears to be poor for the other translocations. Therefore, searching for translocations involving not only IGH, but also IGL and IGK, by banding and molecular cytogenetics is required. Furthermore, it is important to identify the partner gene to ensure the patients receive the optimal treatment.

SUBMITTER: DE Braekeleer M

PROVIDER: S-EPMC4840758 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature

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Immunoglobulin gene translocations in chronic lymphocytic leukemia: A report of 35 patients and review of the literature.

DE Braekeleer Marc M Tous Corine C Guéganic Nadia N LE Bris Marie-Josée MJ Basinko Audrey A Morel Frédéric F Douet-Guilbert Nathalie N

Molecular and clinical oncology 20160226 5

Chronic lymphocytic leukemia (CLL) represents the most common hematological malignancy in Western countries, with a highly heterogeneous clinical course and prognosis. Translocations involving the immunoglobulin (IG) genes are regularly identified. From 2000 to 2014, we identified an IG gene translocation in 18 of the 396 patients investigated at diagnosis (4.6%) and in 17 of the 275 analyzed during follow-up (6.2%). A total of 4 patients in whom the IG translocation was identified at follow-up ...[more]

PMID: 27123263

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Project description:Immunoglobulin heavy chain translocations (IGH-t) have occasionally been reported in Chinese patients with chronic lymphocytic leukemia (CLL). The objective of the present study was to identify the clinicopathologic features of patients with IGH-t CLL and compare them with those of patients with non-IGH-t CLL. We performed fluorescence in situ hybridization (FISH) based on a routine CLL prognostic FISH panel using IGH, IGH-BCL2, BCL3, IGH-CMYC, and BCL6 FISH probes. Furthermore, we retrospectively evaluated the clinical features of 138 newly diagnosed CLL patients via chromosome banding analysis (CBA), FISH, and targeted next-generation sequencing. IGH-t was identified in 25 patients (18.1%). Patients with IGH-t CLL had lower flow scores than those with non-IGH-t CLL. The most frequent translocation was t(14;18) (10 patients), followed by t(14;19) (3 patients), and t(2;14)(p13;q32), t(7;14)(q21.2;q12), t(9;14)(p13;q32) (3 patients). The remaining nine patients included three with abnormal karyotypes without translocation involving 14q32, four with a normal karyotype, and two who failed CBA. The most frequently concomitant FISH-detected aberrations were 13q deletion, followed by +12 and TP53 deletion, while one case involved ATM deletion. Complex karyotypes were detected in five patients with IGH-t CLL, in whom all partner genes were non-BCL2. Available mutational information indicated that KMT2D mutation was the most frequent mutation among tested 70 patients, while TP53 mutation was the most frequent mutation in the IGH-t group. Moreover, the IGH-t group had higher FBXW7 (P=0.014) and ATM (P=0.004) mutations than the non-IGH-t group, and this difference was statistically significant. Our study demonstrates that IGH-t is not uncommon among Chinese CLL patients, and that its partner genes are multiple. The gene mutational profile of the IGH-t group was distinct from that of the non-IGH-t group, and the concomitant chromosomal abnormalities within the IGH-t CLL group differed. Thus, identification of IGH-t and its partner genes in CLL patients may help further refine risk stratification and strengthen the accurate management in CLL patients.

Dataset Information

Immunoglobulin gene translocations in chronic lymphocytic leukemia: A report of 35 patients and review of the literature.

Publications

Immunoglobulin gene translocations in chronic lymphocytic leukemia: A report of 35 patients and review of the literature.

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