HOPES that symptoms of Down鈥檚 syndrome could be reversed have been raised by the silencing of the extra chromosome that causes the condition.
at the University of Massachusetts Medical School in Worcester took skin cells from men with the condition and 鈥渞ewound鈥� them into an embryonic state.
People with Down鈥檚 have an extra copy of chromosome 21, altering the way they develop. Into this extra chromosome, her team inserted a copy of a gene called XIST. This gene has a silencing function and is normally found on the X chromosome, where it is needed to suppress one of the two X chromosomes in females.
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聯The XIST gene appeared to silence the extra chromosome found in people with Down鈥檚聰
With XIST activated, the extra chromosome 21 seemed silenced. These cells developed normally, and within two weeks had formed neural rosettes, clusters of cells that form the central nervous system. None had done so in untreated cells.
XIST activation also prevented the expression of an APP gene present on the extra chromosome that makes beta-amyloid 鈥� a protein linked to Alzheimer鈥檚 disease and which hastens the progression of Down鈥檚 syndrome ().
Intervening in a live embryo is not likely, though. 鈥淚 can鈥檛 see how it could be done in all relevant cells in an embryo at the time Down鈥檚 would be diagnosed,鈥� says Robin Lovell-Badge of London鈥檚 National Institute of Medical Research.
Victor Tybulewicz, also at the NIMR, thinks the therapy鈥檚 value will be in explaining what goes wrong. 鈥淚t can be used to switch off the chromosome at different times, to understand if some consequences could be reversed,鈥� he says.
Elizabeth Fisher at University College London says it might be possible to treat some symptoms by silencing the chromosome in certain areas of the body.
This article appeared in print under the headline 鈥淐ould symptoms of Down鈥檚 be reversed?鈥�
