t(2;8)(p23;p11) KAT6A/ASXL2

2013-11-01   Jean-Loup Huret  

1.Genetics, Dept Medical Information, University of Poitiers, CHU Poitiers Hospital, F-86021 Poitiers, France

Clinics and Pathology

Disease

Treatment-related myelodysplastic syndrome (t-MDS)

Epidemiology

Only one case to date, a 6-year old girl who have had a M2 acute myeloid leukemia (M2-AML) with a t(8;21)(q22;q22), treated with epipodophyllotoxin, 17 months before onset of a therapy related myelodysplasia. She died 14 months after diagnosis of the t-MDS (Imamura et al., 2003).

Genes Involved and Proteins

Gene name
ASXL2 (additional sex combs like 2, transcriptional regulator)
Location
2p23.3
Protein description
Polycomb-group (PcG) and trithorax-group (trxG) proteins regulate histone methylation to establish repressive and active chromatin configurations in Drosophila. Mutations in Asx (the homolog of ASXL2) enhance both Polycomb-group (PcG) and trithorax-group (trxG) mutant phenotypes (Baskind et al., 2009). ASXL2 is an enhancer of PcG activity. ASXL2 and the histone methyltansferase EZH2 (7q36) directly represses MYH7 (14q11) (Beta-Myosin Heavy Chain) (Lai et al., 2012). ASXL2 is implicated in prostate, breast, pancreatic cancers (review in Katoh, 2013). EPC1-ASXL2 fusion gene has been found in adult T-cell leukaemia/lymphoma with a t(2;10)(p23;p11) (Nakahata et al., 2009). EPC1 (10p11) is also a component of the histone acetyltransferase complex.
Gene name
KAT6A (MYST histone acetyltransferase (monocytic leukemia) 3
Location
8p11.21
Note
KAT6A is also known as MYST3, or MOZ.
Protein description
KAT6A is a histone acetyltransferase (HAT). KAT6A has intrinsic HAT activity; KAT6A also forms complexes with MEAF6 (1p34), ING5 (2q37), and BRPF1 (3p25) to acetylate histones H3. KAT6A is a transcriptional co-activator; it interacts with RUNX1 (21q22) and SPI1/PU.1 (11p11) to regulate the expression of haematopoietic-related genes; KAT6A and MLL (11q23), an histone methyltransferase, cooperate to regulate HOX genes, which are key genes in human cord blood CD34+ cells progenitors, and are critical for leukemogenesis. KAT6A is also an epigenetic regulator of haematopoiesis (reviews in Perez-Campo et al., 2013; Yang and Ullah, 2007).

Result of the Chromosomal Anomaly

Description

Exons 2-13 of ASXL2 are fused to exons 1-14 of the KAT6A (Katoh and Katoh, 2004).

Article Bibliography

Pubmed IDLast YearTitleAuthors
192707452009Functional conservation of Asxl2, a murine homolog for the Drosophila enhancer of trithorax and polycomb group gene Asx.Baskind HA et al
126191662003Rearrangement of the MOZ gene in pediatric therapy-related myelodysplastic syndrome with a novel chromosomal translocation t(2;8)(p23;p11).Imamura T et al
151386072004Identification and characterization of ASXL3 gene in silico.Katoh M et al
237360282013Functional and cancer genomics of ASXL family members.Katoh M et al
230465162012Maintenance of adult cardiac function requires the chromatin factor Asxl2.Lai HL et al
194847612009Alteration of enhancer of polycomb 1 at 10p11.2 is one of the genetic events leading to development of adult T-cell leukemia/lymphoma.Nakahata S et al
233470992013The MYSTerious MOZ, a histone acetyltransferase with a key role in haematopoiesis.Perez-Campo FM et al
176940822007MOZ and MORF, two large MYSTic HATs in normal and cancer stem cells.Yang XJ et al

Summary

Fusion gene

KAT6A/ASXL2 KAT6A (8p11.21) ASXL2 (2p23.3) M t(2;8)(p23;p11)|KAT6A/ASXL2 KAT6A (8p11.21) ASXL2 (2p23.3) TIC

Citation

Jean-Loup Huret

t(2;8)(p23;p11) KAT6A/ASXL2

Atlas Genet Cytogenet Oncol Haematol. 2013-11-01

Online version: http://atlasgeneticsoncology.org/haematological/1427/haematological-explorer/js/hgnc