|Written||2008-04||Nathalie Douet-Guilbert, Jean-Luc Laï, Joris Andrieux, Audrey Basinko, Marie-Josée Le Bris, Frédéric Morel, Marc De Braekeleer|
|Laboratoire d'Histologie, d'Embryologie et de Cytogénétique, Université de Bretagne Occidentale, Faculté de Médecine et des Sciences de la Santé, UMR-S613, Brest F-29200, France (NDG, AB, MJLB, FM, MDB); INSERM U613, Brest F-29200, France (NDG, FM, MDB); Laboratoire de Génétique Médical, Hopital Jeanne de Flandre, CHRU de Lille, France (JLL, JA)|
|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||9989/3 Myelodysplastic syndrome, unclassifiable|
|Partial karyotypes for ider(20q) in G-banding (left) and R-banding (right).|
|Clinics and Pathology|
|Disease||Myelodysplastic syndrome (21 cases), Acute Myeloid Leukemia (5 cases), Chronic Myelomonocytic Leukemia (1 case).|
|Phenotype / cell stem origin|| Thrombopenia (90%) with anemia (60%).|
Dysplastic changes in bone marrow: dyserythropoeisis associated with dysgranulopoieisis and/or dysmegakaryocytopoeisis.
|Epidemiology|| The frequency of ider(20q) is estimated at 0.49% in myelodysplastic syndrome and 0.26% in acute myeloid leukemia according to one study.|
They are found in older patients (average age: 68 years; range: 38-91).
|Prognosis||Prognosis of patients with ider(20q) seems to be poor compared to patients with del(20q), but it is unclear due to the small number of cases.|
|Cytogenetics Morphological|| A monosomy of chromosome 20 with small metacentric marker chromosome: 46,XX or XY,-20,+mar is most likely an isoderivative of chromosome 20.|
The ider(20)(q10)del(20)(q11q13) is a variant of del(20)(q11q13).
| Ideograms of normal chromosome 20, of del(20q), of ider(20q) and commonly deleted regions (CDR1, CDR2) and commonly retained regions (CRR1 et CRR2).|
The ider(20q) is described as a secondary event, signing a clonal evolution of deletion 20q positive cells.
The formation of ider(20q) results from loss of the short arm of chromosome 20 and duplication of the deleted long arm of chromosome 20.
|Cytogenetics Molecular|| The ider(20q) is monocentric or dicentric.|
The proximal breakpoints are consistently located in 20q11.21 band. The distal breakpoints span from band 20q13.13 to band 20q13.33.
The commonly deleted region include the short arm of chromosome 20 and a large region on the long arm of chromosome 20 spanning from 20q11.21 to 20q13.13.
A commonly proximal retained region (from centromere to 20q11.21) and commonly distal retained region (from 20q13.33 to telomere 20qter) of the long arm of chromosome 20 were determined. These retained regions are duplicated.
|FISH with subtelomeric probes 20p (Green signal) and 20q (Red signals). The ider(20q) contains two red signals and no green signal.|
|Additional anomalies|| Additional anomalies in decreasing frequency: |
|Genes involved and Proteins|
|Note||To explain specific phenotype, loss of tumor suppressor genes in deleted region ( ADA, L3MBTL ) and gene dosage effect of genes located on the retained region of chromosome 20 are suggested.|
|FISH studies identify the i(20q-) anomaly as a der(20)del(20)(q11q13)idic(20)(p11).|
|Li T, Xue Y, Wu Y, Pan J.|
|Genes Chromosomes Cancer 2006; 45(6):536-539.|
|Isochromosome of a deleted 20q may be a relatively common abnormality in myeloid malignancies.|
|Ligon AH, DeAngelo DJ, Atkins L, Dal Cin P.|
|Cancer Genet Cytogenet 2005; 162(1):89-91.|
|A comparison of two contrasting recurrent isochromosomes 20 found in myelodysplastic syndromes suggests that retention of proximal 20q is a significant factor in myeloid malignancies.|
|Mackinnon RN, Campbell LJ.|
|Cancer Genet Cytogenet 2005; 163(2):176-179.|
|Isochromosome of a deleted 20q: a rare but recurrent chromosome abnormality in myelodysplastic syndromes.|
|Saunders K, Czepulkowski B, Sivalingam R, Hayes JPLA, Aldouri M, Sekhar M et al.|
|Cancer Genet Cytogenet 2005; 156:154-157.|
|This paper should be referenced as such :|
|Douet-Guilbert, N ; Lai, JL ; Andrieux, J ; Basinko, A ; Le, Bris MJ ; Morel, F ; De, Braekeleer M|
|ider(20q) in Myeloid Malignancies|
|Atlas Genet Cytogenet Oncol Haematol. 2009;13(4):297-299.|
|Free journal version : [ pdf ] [ DOI ]|
|On line version : http://AtlasGeneticsOncology.org/Anomalies/ider20qMMID1481.html|
|Translocations implicated (Data extracted from papers in the Atlas)|
|ider(20q) in Myeloid Malignancies|
|Mitelman database||ider(20q) [Case List] ider(20q) [Transloc-MCList] in [Fusion-MCList]|
|arrayMap (UZH-SIB Zurich)||Topo ( C42) Morph ( 9861/3) - [auto + random 100 samples .. if exist ] [tabulated segments]|
|arrayMap (UZH-SIB Zurich)||Topo ( C42) Morph ( 9989/3) - [auto + random 100 samples .. if exist ] [tabulated segments]|
|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 : Wed Jan 10 17:18:25 CET 2018|
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