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ider(20q) in Myeloid Malignancies

Written2008-04Nathalie 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)

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ICD-Morpho 9861/3 AML with mutated NPM1; AML with mutated CEBPA; Acute myeloid leukaemia, NOS
ICD-Morpho 9989/3 Myelodysplastic syndrome, unclassifiable
Atlas_Id 1481
  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:
  • del(20q) detected by conventional cytogenetics and/or by FISH
  • 2 copies of ider(20q)
  • monosomy 7
  • complex karyotypes in acute myeloid leukemia
  • 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.
    PMID 16506189
    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.
    PMID 16157208
    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.
    PMID 16337864
    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.
    PMID 15642396


    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 :

    Translocations implicated (Data extracted from papers in the Atlas)

     ider(20q) in Myeloid Malignancies

    External links

    Mitelman databaseider(20q)
    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 articlesautomatic search in PubMed
    Last year articlesautomatic search in PubMed
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