del(20q) in myeloid malignancies

Identity

	del(20q) G- banding (left) - Courtesy Diane H. Norback, Eric B. Johnson, Sara Morrison-Delap Cytogenetics at theWaisman Center; R-banding (right) - top: Courtesy Jean-Luc Lai; bottom: Editor

Clinics and Pathology

Disease	a very large spectrum of hematological malignancies as myelodysplastic syndromes (MDS), acute non lymphocytic leukemias (ANLL), polycythemia vera, chronic neutrophilic leukemia
Phenotype / cell stem origin	as described in various types of hematological disorders, 20q- appears as a primary karyotypic abnormality occurring in a pluripotential hematopoietic stem cell; the pathogenic mechanism by which 20q- alters the hematopoietic stem cells in hematological disorders remains unknown; 20q- may confer a proliferative advantage to myeloid cells through deletion of a tumor suppressor gene
Epidemiology	an interstitial or terminal deletion of the long arm of chromosome 20 (20q-) has been described as the second most frequent sole clonal structural abnormality (5 %) behind t(9.22)
Prognosis	in MDS, 20q- alone is associated with a good prognosis regarding survival and potential for AML evolution, as defined by the International Prognostic Scoring System (IPSS) for MDS prognosis in de novo acute leukemia, a poor response to treatment and a reduced survival is observed in myeloproliferative disorders, the presence of 20q does not appear to adversely affect survival

Cytogenetics

Cytogenetics Morphological	the breakpoint on chromosome 20 is not constant; 20q- is frequently associated with other cytogenetic abnormalities as del(5q), trisomy 8, trisomy 21, deletions or translocations involving the long arm of chromosome 13; a newly described translocation t(11;20)(p15;q11) resulting in a NUP98- TOP1 fusion gene was described in therapy-related myelodysplastic syndrome (RAEB); t(11;20)(p15;q11) is a rare recurrent translocation reported in patients with MDS, ANLL and polycythemia vera
Cytogenetics Molecular	a small fragment (around 8 Mb), proximally flanked by D20S206 and distally by D20S119 and UT 654 was identified using FISH
Additional anomalies	del(5q), trisomy 8, deletions or translocations involving 13q and trisomy 21

Genes involved and Proteins

Note

genes remaining within this deleted region are topoisomerase 1 (TPO1-OMIN 126420), phospholipase C (PLC1), hepatocyte factor nuclear 4 (HNF4) and adenosine desaminase (ADA); recently, a new gene KRML transcriptional regulator was mapped in the smallest commonly deleted region in malignant myeloid leukemias

External links

Other database	del(20q) in myeloid malignancies	Mitelman database (CGAP - NCBI)

Bibliography

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Contributor(s)

Written	12-2000	Chrystèle Bilhou-Nabera

Citation

This paper should be referenced as such :

Bilhou-Nabera C . del(20q) in myeloid malignancies. Atlas Genet Cytogenet Oncol Haematol. December 2000 . URL : http://AtlasGeneticsOncology.org/Genes/del20qID1040.html

© Atlas of Genetics and Cytogenetics in Oncology and Haematology

indexed on : Wed Sep 24 21:05:51 2008

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