del(20q) in myeloid malignancies

2000-12-01 Chrystè Bilhou-Nabera Affiliation

Clinics and Pathology

Disease

a very large spectrum of hematological malignancies as myelodysplastic syndromes (MDS), acute myeloid leukemias (AML), polycythemia vera, chronic neutrophilic leukemia

Phenotype stem cell 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, AML 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 (TOP1-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

Bibliography

Pubmed ID	Last Year	Title	Authors
10556215	1999	The t(11;20)(p15;q11) chromosomal translocation associated with therapy-related myelodysplastic syndrome results in an NUP98-TOP1 fusion.	Ahuja HG et al
8289501	1994	The prognostic significance of deletion of the long arm of chromosome 20 in myeloid disorders.	Campbell LJ et al
9058730	1997	International scoring system for evaluating prognosis in myelodysplastic syndromes.	Greenberg P et al
8929482	1996	Hematologic disorders associated with deletions of chromosome 20q: a clinicopathologic study of 107 patients.	Kurtin PJ et al
10444328	1999	Human KRML (MAFB): cDNA cloning, genomic structure, and evaluation as a candidate tumor suppressor gene in myeloid leukemias.	Wang PW et al
9491317	1998	Refinement of the commonly deleted segment in myeloid leukemias with a del(20q).	Wang PW et al

Summary

del(20q) Fluorescence in situ hybridization using XL del(20q) probe (Metasystems, Germany) and Vysis LSI D20S108/20q12 probe showing 2 signals on normal A,B) and 1 signal on metaphase with deletion of 20q12 and/or 20qter (red signal) u2013 Courtesy Adriana Zamecnikova. Partial karyotypes with 20q deletions (D): G- banding Left: u2013 Courtesy Adriana Zamecnikova; Center- Courtesy Diane H. Norback, Eric B. Johnson, Sara Morrison-Delap UW Cytogenetic Services; Right: R-banding - Courtesy Hossein Mossafa (top), Jean-Luc Lai (middle), (bottom) Jean Loup Huret.

Citation

Chrystè Bilhou-Nabera

del(20q) in myeloid malignancies

Atlas Genet Cytogenet Oncol Haematol. 2000-12-01

Online version: http://atlasgeneticsoncology.org/haematological/1040/del(20q)-in-myeloid-malignancies