| Written | 2007-07 | Emmanuelle Clappier, Jean Soulier |
| Group Genome Rearrangements, Cancer, Hematology Laboratory APHP, INSERM U728, Paris 7 University, Institut Universitaire d_Hématologie, Hôpital Saint-Louis, Paris, France |
| Identity |
| ICD-Topo | C420,C421,C424 BLOOD, BONE MARROW, & HEMATOPOIETIC SYS |
| ICD-Morpho | 9837/3 T lymphoblastic leukaemia/lymphoma |
| Atlas_Id | 1465 |
 | |
| R-band analysis. Partial karyotype showing t(6;7)(q23;q34) | |
| Clinics and Pathology |
| Disease | T cell acute lymphoblastic leukemia (T-ALL). |
| Phenotype / cell stem origin | T cell precursor. |
| Epidemiology | Less than 5% among a series of non selected adult and pediatric T-ALLs (n = 3 out of 92). Six cases were described, all of them children, and 5 out of 6 being under 3 years old (1.1, 1.3, 1.8, 2.5, and 2.9 years old, respectively), which is very young for T-cell leukemia. The t(6;7) translocation could therefore be relatively common in this very low range of age. |
| Cytology | Lymphoblasts |
| Prognosis | The prognosis is yet to be evaluated. |
| Cytogenetics |
| Cytogenetics Morphological | t(6;7)(q23;q34) may be barely detectable by chromosome banding techniques alone. |
 | |
| Left: Whole chromosome painting of chromosomes 6 (green) and 7 (red). Right: Locus-specific break-apart FISH using 6q23 probes RP11-184J4 (red) and RP11-845K5 (green) showing translocation involving the 6q23 locus. | |
| Cytogenetics Molecular | Involvement of the TCRB locus and the MYB locus can be demonstrated using flanking FISH probes. |
| Genes involved and Proteins |
| Gene Name | TRB (T cell Receptor Beta) |
| Location | 7q34 |
| Protein | T-cell receptor beta chain |
| Gene Name | MYB (v-myb myeloblastosis viral oncogene homolog (avian)) |
| Location | 6q23.3 |
| Dna / Rna | Spans over 38 kb, 15 exons (and additionnal alternative exons), mRNA 3.3 kb. |
| Protein | v-myb myeloblastosis viral oncogene homolog. Transcription factor. 640 amino acids. |
| Gene Name | AHI1 (Abelson helper integration site 1) |
| Location | 6q23.3 |
| Dna / Rna | Spans over 214 kb, 28 exons (and additional alternative exons), mRNA 5.5 kb. |
| Protein | Jouberin (Abelson helper integration site 1 protein homolog) (AHI-1). 1196 amino acids including one SH3 domain and WD repeats. |
| Result of the chromosomal anomaly |
| Note | No fusion gene The t(6;7)(q23.3;q34) translocation results in juxtaposition of TRB regulatory sequences to the MYB-AHI1 locus. It results in deregulated expression of C-MYB, as demonstrated by skewed allelic expression. |
| Oncogenesis | C-MYB is a transcription factor involved in hematopoiesis. In T-cell differenciation, discrete threshold levels of MYB activity regulate transition through distinct stages, suggesting that a deregulated expression could disturb the maturation process and play a role in oncogenesis. A potential role of AHI1 deregulation as a cofactor has to be evaluated. Of note, the same locus at 6q23.3 is also involved in short tandem duplications of a about 230 kb genomic region which includes the C-MYB gene (about 10% T-ALL in children and adults). This somatic abnormality can be detected by array-CGH, genomic Q-PCR or fiber-FISH, but not or hardly by standard metaphasic or interphasic FISH. |
| 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 |
| The C-MYB locus is involved in chromosomal translocation and genomic duplications in human T-cell acute leukemia (T-ALL), the translocation defining a new T-ALL subtype in very young children. |
| Clappier E, Cuccuini W, Kalota A, Crinquette A, Cayuela JM, Dik WA, Langerak AW, Montpellier B, Nadel B, Walrafen P, Delattre O, Aurias A, Leblanc T, Dombret H, Gewirtz AM, Baruchel A, Sigaux F, Soulier J |
| Blood. 2007 ; 110 (4) : 1251-1261. |
| PMID 17452517 |
| Duplication of the MYB oncogene in T cell acute lymphoblastic leukemia. |
| Lahortiga I, De Keersmaecker K, Van Vlierberghe P, Graux C, Cauwelier B, Lambert F, Mentens N, Beverloo HB, Pieters R, Speleman F, Odero MD, Bauters M, Froyen G, Marynen P, Vandenberghe P, Wlodarska I, Meijerink JP, Cools J |
| Nature genetics. 2007 ; 39 (5) : 593-595. |
| PMID 17435759 |
| Analysis of balanced rearrangements of chromosome 6 in acute leukemia: clustered breakpoints in q22-q23 and possible involvement of c-MYB in a new recurrent translocation, t(6;7)(q23;q32 through 36). |
| Sinclair P, Harrison CJ, Jarosová M, Foroni L |
| Haematologica. 2005 ; 90 (5) : 602-611. |
| PMID 15921375 |
| Citation |
| This paper should be referenced as such : |
| Clappier, E ; Soulier, J |
| t(6;7)(q23;q34) |
| Atlas Genet Cytogenet Oncol Haematol. 2008;12(3):248-249. |
| Free journal version : [ pdf ] [ DOI ] |
| On line version : http://AtlasGeneticsOncology.org/Anomalies/t0607q23q34ID1465.html |
| Translocations implicated (Data extracted from papers in the Atlas) |
| t(6;7)(q23;q34) TRB/MYB and AHI1 | |
| External links |
| REVIEW articles | automatic search in PubMed |
| Last year articles | automatic search in PubMed |
| All articles | automatic search in PubMed |
| © Atlas of Genetics and Cytogenetics in Oncology and Haematology | indexed on : Tue Nov 6 14:03:09 CET 2018 |
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