| Clinics and Pathology |
| Disease | T-cell Acute lymphoblastic leukemia (T-ALL) |
| Epidemiology | Rare. |
| Clinics | One case reported: The patient was a 7-years-old female with high white blood count with lymphoblasts positive for T-cell antigens; cerebrospinal fluid négative for malignant cells; superior mediastinal mass. |
| Prognosis | The patient attained a complete remission with standard chemotherapy but relapsed and died after 4 months of therapy. |
| Cytogenetics |
| Cytogenetics Morphological | The t(14 ;21)(q11.2 ;q22)was accompanied with del(6)(q21). Cryptic t(14 ;21) translocation cases may exist. |
| Genes involved and Proteins |
| Gene Name | TCRA |
| Location | 14q11.2 |
| Protein | T cell receptor |
| Gene Name | BHLHB1 |
| Location | 21q22 |
| Note | alias OLIG2 |
| Dna / Rna | This gene maps within a 9 to 12 Mb region of chromosome 21q22. |
| Protein | This gene was shown to possess a helix-loop-helix (bHLH) motif witch inhibits the E2A function in transfection assays. E2A is required for normal T-cell differentiation. |
| Result of the chromosomal anomaly |
| Note | Translocation of the BHLHB1 gene 130kb upstream of the TCRA enhancer. This translocation activates the BHLHB1 gene and produces high levels of BHLHB1 mRNA. Expression of HLHB1 inhibits E2A-mediated transcription activation in vitro. |
| Note | No fusion protein. |
| Oncogenesis | Several helix-loop-helix (HLH) proteins are proposed to function as transcriptionnal regulatory factors based on their ability to bind in vitro the E-box motif of transcriptional enhancers. The observation that ectopic BHLHB1 expression can onhibit E2A activity suggests that BHLHB1 exerts its leukemogenic effects through a functional inhibition of E2A. |
| External links |
| Other database | t(14 ;21)(q11;q22) | Mitelman database (CGAP - NCBI) | |
| Other database | t(14 ;21)(q11;q22) | CancerChromosomes (NCBI) |
| Bibliography |
| t(5;14)(q33-34;q11), a new recurring cytogenetic abnormality in childhood acute leukemia. |
| Whitlock JA, Raimondi SC, Harbott J, Morris SW, McCurley TL, Hansen-Hagge TE, Ludwig WD, Weimann G, Bartram CR |
| Leukemia : official journal of the Leukemia Society of America, Leukemia Research Fund, U.K. 1994 ; 8 (9) : 1539-1543. |
| PMID 8090032 |
| Cytogenetic abnormalities in adult acute lymphoblastic leukemia: correlations with hematologic findings outcome. A Collaborative Study of the Group Franˆßais de Cytogˆ©nˆ©tique Hˆ©matologique. |
| Blood. 1996 ; 87 (8) : 3135-3142. |
| PMID 8605327 |
| E2A deficiency leads to abnormalities in alphabeta T-cell development and to rapid development of T-cell lymphomas. |
| Bain G, Engel I, Robanus Maandag EC, te Riele HP, Voland JR, Sharp LL, Chun J, Huey B, Pinkel D, Murre C |
| Molecular and cellular biology. 1997 ; 17 (8) : 4782-4791. |
| PMID 9234734 |
| The t(14;21)(q11.2;q22) chromosomal translocation associated with T-cell acute lymphoblastic leukemia activates the BHLHB1 gene. |
| Wang J, Jani-Sait SN, Escalon EA, Carroll AJ, de Jong PJ, Kirsch IR, Aplan PD |
| Proceedings of the National Academy of Sciences of the United States of America. 2000 ; 97 (7) : 3497-3502. |
| PMID 10737801 |
| Contributor(s) |
| Written | 11-2004 | Jacques Boyer |
| Citation |
| This paper should be referenced as such : |
| Boyer J . t(14 ;21)(q11;q22). Atlas Genet Cytogenet Oncol Haematol. November 2004 . URL : http://AtlasGeneticsOncology.org/Genes/t1421q11q22ID1180.html |
| © Atlas of Genetics and Cytogenetics in Oncology and Haematology | indexed on : Wed Sep 24 21:07:35 2008 |
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