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t(6;20)(q15;q11.2) BACH2/BCL2L1

Written2012-10Thomas Burmeister
Charite, Med. Klinik fur Hamatologie, Onkologie und Tumorimmunologie, Hindenburgdamm 30, 12200 Berlin, Germany

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Identity

ICD-Topo C420,C421,C424 BLOOD, BONE MARROW, & HEMATOPOIETIC SYS
Atlas_Id 1614

Clinics and Pathology

Disease High-grade B-cell lymphoma
Note The chromosomal translocation t(6;20)(q15;q11.2) was detected in the cell line BLUE-1. This cell line was established from a bone marrow sample obtained from a patient with relapsed high-grade B-cell lymphoma, initially histologically classified as Burkitt lymphoma (Burmeister et al., 2006). The cell line also carries the Burkitt-typical t(8;14)(q24;q32) with MYC-IGHJ fusion. Further characterization of the t(6;20)(q15;q11.2) led to the identification of a chimeric BACH2-BCL2L1 fusion transcript, showing a fusion of the first non-coding BACH2 exon to the coding part of BCL2L1. The translocation thus effectively leads to an overexpression of BCL2L1.
Phenotype / cell stem origin The BLUE-1 cell line has the following immunophenotype: CD2-, cyCD3-, CD5-, CD7-, CD10+, CD19+, CD20-, cyCD22+, CD23-, cyIgM-, CD56-, CD33-, MPO-7-, CD34-, HLA-DR+, TdT-, CD52+.
Epidemiology The cell line BLUE-1 is the only known case.
Clinics The patient from whom the cell line was derived showed a very aggressive form of lymphoma. Despite intensive immunochemotherapy he relapsed, developed meningeal involvement and died 3 months after the cell line was established.
Cytology Cytomorphology and immunostaining of the BLUE-1 cells was compatible with the diagnosis of Burkitt lymphoma (Burmeister et al., 2006).

Cytogenetics

Cytogenetics Morphological The inital karyotype of BLUE-1 was the following: 46,XY,t(6;20)(q13;q11.2),t(8;14)(q24;q32).
After one year in continuous culture the karyotype had evolved: 53,XY,+6,t(6;20)(q15;q11.2),der(6)t(6;20)(q15;q11.2),t(8;14)(q24;q32),+13,+16,+20,+20,der(20)del(20)(p12.2p13.2)t(6;20)(q15;q11.2)t(6;11)(q16;p13),+der(20),+21 (Burmeister et al., 2006). The second +20 was later classified as third der(20).
 
  The evolved BLUE-1 karyotype shows one der(6)t(6;20)(q13;q11.2), one +6 and three der(20)t(6;20)(q15;q11.2) (one long der(20) and two short der(20)) in addition to the normal chromosome 20 (Burmeister et al., 2011).
Cytogenetics Molecular Molecular cytogenetics showed a MYC-IGH juxtaposition. The following BAC clones were used: WI2-1694H13 (8q24), RP11-815O20 and RP11-965B13 (IGH-Eμ). The t(6;20)(q15;q11.2) was characterized using the BAC clones RP11-21G12, RP1-154G14, RP1-45N11, RP1-104D1 (on chr 6) and RP3-324O17, RP5-857M17, RP11-243J16 and RP1-310O13 (on chr 20).

Genes involved and Proteins

Gene NameBACH2 (BTB and CNC homology 1, basic leucine zipper transcription factor 2)
Location 6q15
Dna / Rna Two different transcripts have been described, one 7-exon 9109 bp transcript and one 9-exon 9215 bp transcript. The coding last 4 exons are shared by both transcripts. Both transcripts encode an 841 aa protein.
Gene NameBCL2L1 (BCL2-like 1)
Location 20q11.21
Dna / Rna Two major BCL2L1 transcripts have been described: one long 2559 bp transcript BCL-XL resulting in the translation of a 233 aa protein and one short 2370 bp transcript BCL-XS, resulting in the translation of a 170 aa protein. The shorter transcript is generated by alternative splicing at the 3' end of BCL2L1 exon 2.

Result of the chromosomal anomaly

Hybrid gene
Note The translocation t(6;20)(q15;q11.2) was characterized using a sequential BAC clone mapping strategy. The BAC clones RP11-243J16 (on chr 20) and RP1-104D1 (on chr 6) covered the chromosomal breakpoint region. The chromosomal breakpoint was not identified but is likely located 5' of the first BCL2L1 exon and 3' of the first BACH2 exon.
Transcript RT-PCR showed a chimeric BACH2-BCL2 fusion transcript. The first non-coding BACH2 exon was fused to the second (partially coding) BCL2L1 exon. This led to an overexpression of BCL2L1 (BCL-XL).
  
Fusion Protein
Note Translation of the BACH2-BCL2L1 transcript resulted in a strong overexpression of BCL2L1 as detected by immunoblotting.
  

To be noted

Additional cases are needed to delineate the epidemiology of this rare entity:
you are welcome to submit a paper to our new Case Report section.

Bibliography

A novel sporadic Burkitt lymphoma cell line (BLUE-1) with a unique t(6;20)(q15;q11.2) rearrangement.
Burmeister T, Macleod RA, Reinhardt R, Mansmann V, Loddenkemper C, Marinets O, Drexler HG, Thiel E, Blau IW.
Leuk Res. 2006 Nov;30(11):1417-23. Epub 2006 May 11.
PMID 16697040
 
A BACH2-BCL2L1 fusion gene resulting from a t(6;20)(q15;q11.2) chromosomal translocation in the lymphoma cell line BLUE-1.
Turkmen S, Riehn M, Klopocki E, Molkentin M, Reinhardt R, Burmeister T.
Genes Chromosomes Cancer. 2011 Jun;50(6):389-96. doi: 10.1002/gcc.20863. Epub 2011 Mar 15.
PMID 21412927
 

Citation

This paper should be referenced as such :
Burmeister, T
t(6;20)(q15;q11.2) BACH2/BCL2L1
Atlas Genet Cytogenet Oncol Haematol. 2013;17(2):132-133.
Free journal version : [ pdf ]   [ DOI ]
On line version : http://AtlasGeneticsOncology.org/Anomalies/t0620q15q11ID1614.html


Translocations implicated (Data extracted from papers in the Atlas)

 t(6;20)(q15;q11.2) BACH2/BCL2L1

External links

arrayMap (UZH-SIB Zurich)BACH2 (6q15) BCL2L1 (20q11.21)

BACH2 (6q15) BCL2L1 (20q11.21)

BACH2 (6q15) BCL2L1 (20q11.21)

Mitelman databaset(6;20)(q15;q11.2) [Case List]    t(6;20)(q15;q11.2) [Association List] Mitelman database (CGAP - NCBI)
arrayMap[select an item]
 
Mitelman databaseBACH2/BCL2L1 [MCList]  BACH2 (6q15) BCL2L1 (20q11.21)
Mitelman databaseBACH2/BCL2L1 [MCList]  BACH2 (6q15) BCL2L1 (20q11.21)
TICdbBACH2/BCL2L1  BACH2 (6q15) BCL2L1 (20q11.21)
 
Disease databaset(6;20)(q15;q11.2) BACH2/BCL2L1
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