Genetic 'Switch' May Help Turn Off Down's Syndrome Genes

Researchers believe that the insertion of one gene can help ward off the extra copy of chromosome 21 that causes Down's syndrome, according to a recent study.

This method could also help researchers learn about the cellular pathways behind the disorder's symptoms and how to approach new treatments.

"It's a strategy that can be applied in multiple ways, and I think can be useful right now," said Jeanne Lawrence, a cell biologist at the University of Massachusetts Medical School in Worcester, and the lead author of the study, via Scientific American.

Researchers worked on mimicking the natural process that prevents one of the two X chromosomes carried by all female mammals.

According to the study, the activation of the XIST gene, which both chromosomes carried, produces an RNA molecule that coats the surface of a chromosome and blocks other genes from expression.

For instance, when one copy of the XIST gene is activated, the X chromosome is silenced.

Lawrence and colleagues spliced the XIST gene into one of three copies of chromosome 21 in cells from a person with Down's syndrome. A genetic 'switch' was then inserted to activate the XIST by dosing the cells with antibiotic doxycycline.

This resulted in less expression of individual genes along chromosome 21 that are thought to cause problems relating to Down's syndrome.

"The idea of shutting off a whole chromosome is extremely interesting" in Down's syndrome research, said stem-cell researcher Nissim Benvenisty of Hebrew University in Jerusalem. 

Researchers believe that further studies involving the activation and deactivation of the XIST gene could help health expert's better understand Down's syndrome.

However, study authors show that disadvantages of turning off the XIST gene may not block all gene expression in the extra chromosome, and thus, could provide inaccurate results.

More information regarding the study can be found in the magazine Nature.