From researchers at U os Mass, the extra 21st chromosome in human cells of Down syndrome was made inactive.
Clinical trials are now underway whose goal is to improve cognition in those with Down syndrome.
Of importance is the fact that the gene that codes for amyloid-beta peptide (which accumulates in excess in the brains of patients with Alzheimer's disease) is located on the 21st chromosome. Those with Down syndrome produce 50 % more of this protein and are at great risk for developing Alzheimer's disease by their early 40's.
Regarding technique, researchers employed the RNA gene that normally inactivates one of a female's X chromosomes called XIST. The team employed zinc finger nuclease technology (a method of editing the genome) to place it into one copy of the 21st chromosome. The receiving chromosome was in an induced pluripotent stem cell derived from fibroblast cells from a patient with Down syndrome.
Nature 2013;E-pub 2013 July 17