| Written | 1999-06 | François Desangles |
| Laboratoire de Biologie, Hopital du Val de Grace, 75230 Paris, France |
| Identity |
| ICD-Topo | C420,C421,C424 BLOOD, BONE MARROW, & HEMATOPOIETIC SYS |
| ICD-Morpho | 9861/3 AML with mutated NPM1; AML with mutated CEBPA; Acute myeloid leukaemia, NOS |
| ICD-Morpho | 9920/3 Therapy-related myeloid neoplasms |
| ICD-Morpho | 9989/3 Myelodysplastic syndrome, unclassifiable |
| Atlas_Id | 1093 |
| Note | -7/del(7q) in childhood blood malignancies exhibits a specific pattern of pathogenesis; chromosome 7 anomalies are not rare in acute lymphocytic leukaemia (ALL); they occur in balanced translocations involving 7p15 or 7q34 in T lineage and 7q22 or 7q32 in B proliferations; monosomy 7 is present in 5 to 6 % of ALL, most often as a secondary anomaly of the t(9;22); the association t(9;22), -7 is present in 16 % of the Ph1+ ALL, i.e. in 3% of ALL as a whole; we will hereunder focuse on -7/del(7q) in adult myeloproliferations |
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| del(7q) Figure 1: Partial karyotypes with 7q deletions (A). Fluorescence in situ hybridization with Vysis D7S486 (7q31)/CEP 7 probe (Abbott moleculars, US) showing 2 green and 2 red signals on normal and one red signal in abnormal metaphases indicating 7q deletion of various sizes (C-H) – Courtesy Adriana Zamecnikova. Figure 2: del(7q) G- banding - Courtesy Jean-Luc Lai and Alain Vanderhaegen; Hybridization with Vysis D7S486 (7q31)/CEP 7 probe (Abbott moleculars, US) showing 1 green and 1 red signal confirming monosomy 7on metaphase and interphase cells – Courtesy Adriana Zamecnikova. | |
| Clinics and Pathology |
| Disease | myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML); they may occur de novo, or be secondary to an exposure to chemical mutagens or to chemotherapy treatments with alkylating agents; may probably also be secondary to immunosuppressive therapy for severe aplastic anemia |
| Phenotype / cell stem origin | |
| Epidemiology | -7 is the most frequent abnormality in secondary myeloid disorders, found in 51% of the cases in a series of 246 cases, while del(7q) was found in 7%, and a partial monosomy 7 as a result of an unbalanced translocation in 8% of cases; in contrast, -7/del(7q) is found in 10% of de novo myeloid disorders; the sex ratio is 1.5 male for 1 female; the proportion of adults with a -7 myeloid disorder grows dramatically after 60 years |
| Clinics | characterized by infectious susceptibility, quick aggravation, and treatment resistance |
| Prognosis | monosomy 7 is classified as a poor prognostic criterium by the International Prognostic Scoring System; the actuarial relapse rate at one year is 82 %, and the 7-yr actuarial event-free survival is 6 %; after an allogeneic bone marrow transplantation, -7 is predictive of an unfavorable outcome |
| Cytogenetics |
| Cytogenetics Morphological | deletion (7q) is always interstitial; cluster of breakpoints in 7q11 to 7q36, is a with two common minimal zones in q22 and in q32-34 |
| Cytogenetics Molecular | using loss of heterogygocity (LOH) studies and YAC libraries, a 2 to 3 Mb segment in 7q22 has been designated as the proximal common deleted area; the 7q33-34 zone is the consensual area for the distal deletion; LOH studies suggest that a specific mechanism, such as mitotic recombination in bone marrow stem cell leading to homozygosity in both granulocytes and lymphocytes, may be implicated |
| Additional anomalies | -5/del(5q), found in 40 to 60 % of the secondary MDS cases; trisomy 8 |
| Variants | the balanced translocation t(1;7)(q10;p10), and many unbalanced translocation, having for consequence a partial monosomy 7 of the 7q22 to 7q34 bands may, in a way, be considered as variants |
| Genes involved and Proteins |
| Note | -7/del(7q) is not only frequent in secondary MDS or AML, but also in leukemias occurring in individuals with constitutional syndromes including predisposition to myeloid disorders; these findings suggest the presence of a putative myeloid leukemia suppressor gene in the commonly deleted genomic segment 7q22 and even multiple genes in 7q22 -31.1 that are playing a role in leukemogenesis; candidate genes are : |
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| Citation |
| This paper should be referenced as such : |
| Desangles, F |
| -7/del(7q) in adults |
| Atlas Genet Cytogenet Oncol Haematol. 1999;3(3):139-140. |
| Free journal version : [ pdf ] [ DOI ] |
| On line version : http://AtlasGeneticsOncology.org/Anomalies/del7qID1093.html |
| Other genes implicated (Data extracted from papers in the Atlas) [ 7 ] |
| Genes | ABL1 | ASXL1 | BCR | DMTF1 | MECOM | FGFR1 | RARA |
| Translocations implicated (Data extracted from papers in the Atlas) |
| del(7q) in adults | |
| External links |
| REVIEW articles | automatic search in PubMed |
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| © Atlas of Genetics and Cytogenetics in Oncology and Haematology | indexed on : Fri Oct 12 18:19:21 CEST 2018 |
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