t(8;12)(q24;q22) BTG1/MYC

2007-10-01   Jean-Loup Huret 

1.Genetics, Dept Medical Information, University of Poitiers, CHU Poitiers Hospital, F-86021 Poitiers, France

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 v-myc myelocytomatosis viral oncogene homolog (avian)
Location
8q24.21
Protein description
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 (BTG anti-proliferation factor 1)
Location
12q21.33
Protein description
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.

Bibliography

Pubmed IDLast YearTitleAuthors
31280401988Initial clonal acute lymphoblastic transformation of chronic lymphocytic leukemia with (11;14) and (8;12) chromosome translocations and acquired homozygosity.Archimbaud E et al
174662952007Role for Btg1 and Btg2 in growth arrest of WEHI-231 cells through arginine methylation following membrane immunoglobulin engagement.Hata K et al
150334462004An anti-proliferative gene BTG1 regulates angiogenesis in vitro.Iwai K et al
20699071991A 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 et al

Summary

Fusion gene

BTG1/MYC BTG1 (12q21.33) MYC (8q24.21) M|BTG1/MYC BTG1 (12q21.33) MYC (8q24.21) M t(8;12)(q24;q22)

Citation

Jean-Loup Huret

t(8;12)(q24;q22) BTG1/MYC

Atlas Genet Cytogenet Oncol Haematol. 2007-10-01

Online version: http://atlasgeneticsoncology.org/haematological/2057/t(8;12)(q24;q22)

External Links