t(8;12)(q24;q22)

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t(8;12)(q24;q22)

Clinics and Pathology

Disease	Chronic lymphocytic leukemia (CLL) in blastic transformation
Note	CLL was diagnosed after bone marrow recovery following intensive chemotherapy for acute lymphoblastic leukemia
Epidemiology	Only one case to date, 69-year-old female patient
Cytogenetics	The patient had a primary t(11;14)(q13;q32) in all lymphocytic/lymphoblastic cells. A subpopulation of cells carried in addition a t(8;12) (q24;q22) together with the loss of the normal chromosome 8 and homozygosity for the abnormal der(8). It is likely that the t(11;14) corresponded to the CLL, and the subclone with t(8;12) to the blast population
Genes	MYC was strongly expressed. The breakpoint on chromosome 8 mapped to the 3' end of the MYC locus
Prognosis	The patient died 5 months after initial blastic phase

Genes involved and Proteins

Gene Name	MYC
Location	8q24
Protein	Transcription factor binding to specific DNA sequences, upon dimerization to Max (Max can also form heterodimers with Mad as well as homodimers with itself). Myc/Max complexes activate transcription and promote cell proliferation and transformation. Mad/Max complexes, repress transcription.

Gene Name	BTG1
Location	12q22
Protein	B-cell translocation gene 1 (BTG1) is an anti-proliferative gene; it regulates cell growth and differentiation. BTG1 is strongly expressed in the G0/G1 phases of the cell cycle, and then down-regulated during the G1 phase. Overexpression of BTG1 results in a retardation of cell proliferation. Potentially high-affinity self-reactive B cells are eliminated through the interaction of membrane Ig (mIg) with self-antigens. Anti-IgM upregulates BTG1 and BTG2, resulting in growth inhibition. Engagement of mIg on the cells results in G1 arrest and eventual apoptosis.

External links

Other database	t(8;12)(q24;q22)	Mitelman database (CGAP - NCBI)
Other database	t(8;12)(q24;q22)	CancerChromosomes (NCBI)

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

Initial clonal acute lymphoblastic transformation of chronic lymphocytic leukemia with (11;14) and (8;12) chromosome translocations and acquired homozygosity.

Archimbaud E, Charrin C, Gentilhomme O, Rimokh R, Guyotat D, Fiere D, Germain D

Acta haematologica. 1988 ; 79 (3) : 168-173.

A chromosome 12 coding region is juxtaposed to the MYC protooncogene locus in a t(8;12)(q24;q22) translocation in a case of B-cell chronic lymphocytic leukemia.

Rimokh R, Rouault JP, Wahbi K, Gadoux M, Lafage M, Archimbaud E, Charrin C, Gentilhomme O, Germain D, Samarut J

Genes, chromosomes & cancer. 1991 ; 3 (1) : 24-36.

An anti-proliferative gene BTG1 regulates angiogenesis in vitro.

Iwai K, Hirata K, Ishida T, Takeuchi S, Hirase T, Rikitake Y, Kojima Y, Inoue N, Kawashima S, Yokoyama M

Biochemical and biophysical research communications. 2004 ; 316 (3) : 628-635.

Role for Btg1 and Btg2 in growth arrest of WEHI-231 cells through arginine methylation following membrane immunoglobulin engagement.

Hata K, Nishijima K, Mizuguchi J

Experimental cell research. 2007 ; 313 (11) : 2356-2366.

Contributor(s)

Written	10-2007	Jean-Loup Huret
		Jean Loup HURET, Genetics, Dept Medical Information, University of Poitiers; CHU Poitiers Hospital, F-86021 Poitiers, France

This paper should be referenced as such :

Huret JL . t(8;12)(q24;q22). Atlas Genet Cytogenet Oncol Haematol. October 2007 .
URL : http://AtlasGeneticsOncology.org/Anomalies/t0812q24q22ID2057.html

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