• What is ASXL1?
  • ASXL1 in Myelodysplastic Syndromes
  • Clinical Trials


Additional sex combs like transcriptional regulator 1 (official symbol ASXL1) is a gene that codes for a chromatin-binding protein. Normal ASXL1 plays a role in embryonic development (Gene 2014). ASXL1 mutations are observed primarily in myelodysplastic syndromes, but they are also observed in colorectal and endometrial cancers (COSMIC).​

Related Pathways

Contributors: Stephen A. Strickland, M.D., MSCI, Annette S. Kim, M.D., Ph.D.

Suggested Citation: Strickland, S., A. Kim. 2015. ASXL1. My Cancer Genome https://www.padiracinnovation.org/content/disease/myelodysplastic-syndromes/asxl1/?tab=0 (Updated December 4).

Last Updated: December 4, 2015

ASXL1 in Myelodysplastic Syndromes

ASXL1 mutations occur in 15.8% of MDS (COSMIC). ASXL1 and EZH2 mutations—both genes that code for chromatin-modifying proteins—are most often observed in refractory cytopenia with multilineage dysplasia (RCMD) and refractory anemia with excess blasts (RAEB), two subtypes of MDS associated with higher risk (Cazzola, Della Porta, and Malcovati 2013). ASXL1 mutations, 70% of which are frameshift mutations (Thol et al. 2011), result in loss of ASXL1 expression, which ultimately results in loss of polycomb repressive complex 2 (PRC2)-mediated gene repression. PRC2 normally represses the expression of several leukemogenic genes. This loss promotes myeloid transformation and leukemogenesis (Abdel-Wahab et al. 2012).

ASXL1 mutations are a prognostic biomarker, associated with shorter overall survival (Bejar et al. 2011; NCCN 2014; Thol et al. 2011).

Contributors: Stephen A. Strickland, M.D., MSCI, Annette S. Kim, M.D., Ph.D.

Suggested Citation: Strickland, S., A. Kim. 2014. ASXL1 in Myelodysplastic Syndromes. My Cancer Genome https://www.padiracinnovation.org/content/disease/myelodysplastic-syndromes/asxl1/ (Updated September 30).

Last Updated: September 30, 2014

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