Scientists Shut Down Chromosome Responsible for Down Syndrome

International   |   Steven Ertelt   |   Jul 17, 2013   |   5:45PM   |   Washington, DC

Scientists say they have been able to turn off the chromosome responsible for Down Syndrome. This stunning achievement raises the prospect that someday a therapy could be developed to prevent or reverse the disorder.

Down Syndrome is a condition that subjects 90 percent of unborn children diagnosed with it to abortion. What if doctors could someday treat unborn children before birth with a drug or therapy that could reverse the disorder? What kind of impact would that have on the incidence of abortion? How would society look if the numbers of people with Down Syndrome took an even more drastic decline?

The Guardian newspaper has more on the development:

In an elegant series of experiments, US researchers took cells from people with DS and silenced the extra chromosome that causes the condition. A treatment based on the work remains a distant hope, but scientists in the field said the feat was the first major step towards a “chromosome therapy” for Down’s syndrome.

“This is a real technical breakthrough. It opens up whole new avenues of research,” said Elizabeth Fisher, professor of neurogenetics at UCL, who was not involved in the study. “This is really the first sniff we’ve had of anything to do with gene therapy for Down’s syndrome.”

Though a full treatment is still many years off, the work will drive the search for therapies that improve common symptoms of DS, from immune and gastrointestinal problems, to childhood leukaemia and early-onset dementia.

“This will accelerate our understanding of the cellular defects in Down’s syndrome and whether they can be treated with certain drugs,” said Jeanne Lawrence, who led the team at the University of Massachusetts.

“The long-range possibility – and it’s an uncertain possibility – is a chromosome therapy for Down’s syndrome. But that is 10 years or more away. I don’t want to get people’s hopes up.”

In a healthy person, almost every cell in the body carries 23 pairs of chromosomes, which hold nearly all of the genes needed for human life. But glitches in the early embryo can sometimes leave babies with too many chromosomes. Down’s syndrome arises when cells have an extra copy of chromosome 21.

Lawrence’s team used “genome editing”, a procedure that allows DNA to be cut and pasted, to drop a gene called XIST into the extra chromosome in cells taken from people with Down’s syndrome.

Once in place, the gene caused a buildup of a version of a molecule called RNA, which coated the extra chromosome and ultimately shut it down.