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Scientists Shut Down Extra Chromosome That Causes Down Syndrome in Isolated Cells (STUDY)
Summary: Researchers have taken a major first step in a possible "chromosome therapy" for Down syndrome by testing the concept of "shutting down" the extra chromosome responsible for the disorder in isolated cells. The discovery opens up new possibilities for future treatments, but it's controversial and could take several years to come to fruition.
By Joanne Van Zuidam | Posted: July 18, 2013
A U.S. research team has corrected the genetic fault that causes Down syndrome. The experiment — in isolated cells — silenced the extra chromosome responsible for the condition. While a treatment is still years away, this discovery brings hope for "chromosome therapy" for the genetic disorder.
In the study, published in the journal Nature, researchers took cells from people with Trisomy 21, as disorder is also called, and silenced the extra chromosome that causes the condition.
"This will accelerate our understanding of the cellular defects in Down 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 syndrome. But that is 10 years or more away. I don't want to get people's hopes up."
The genetic disorder arises when cells have an extra copy of chromosome 21.
As reported by the The Guardian, 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 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.
Lawrence's work shows that the gene can shut down other chromosomes too, a finding that paves the way for treating a range of other "trisomy" disorders, such as Edward syndrome and Patau syndrome, caused by extra copies of chromosomes 18 and 13 respectively.
The research team has already begun work in mice that silences the extra chromosome 21 in early-stage embryos. "That would correct the whole mouse, but it's not really practical in humans," said Lawrence.
What's more, chromosome therapy is controversial — to prevent Down syndrome, the "genome editing" would have to be performed on an embryo or fetus in the womb, and correct most, if not all, of the future child's cells. That science is far beyond what is possible, or allowed, today.
Photo credit: stock.xchng
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