Loss of the Epigenetically Inactivated-X-Chromosome (Barr Body) a Potential Biomarker for Breast Cancer Development

Background: Attention has recently reawakened to loss of the epigenetically inactive-X chromosome ‘‘Barr body’’ as a key prevalent event in development of breast cancer and other malignancies. This study was aimed to investigate the incidence of Barr body loss as well as the expression levels of XIST, X-inactivespecific-transcript, in a set of Iraqi breast cancer patients.

Method: Eighty peripheral blood samples were collected from 60 patients diagnosed with breast cancer and 20 healthy age-matched controls for Barr body blood smears screening and XIST qPCR gene expression analysis.

Results: The results showed significant reduction in Barr body count (percentage mean) in breast cancer patients in comparison with controls (0.15 vs. 0.56,P = 1.14 *10^-21). Also, Barr body count was able to discriminate between breast cancer patients and their healthy controls. The XIST gene expression was also down regulated in the vast majority (95%, 57/60) of studied breast cancer patients, suggesting a potential key role for this gene in the development of breast cancer.

Conclusion: This study produced results which corroborate findings from a great deal of the previous work and showed strong association between loss of Barr body and down regulation of XIST in breast cancer patients. In addition, Barr body and XIST expression could be investigated further for their utility as an early screening or diagnostic method especially in high risk individuals for breast cancer and possibly for other malignancies.