According to research from the Sanford Burnham Medical Research Institute and published in the journal Nature Medicine, Down syndrome, a result of being born with three copies of chromosome 21 rather than two, causes over-expression of miR-155, which inhibits the expression of the SNX27 gene and results in synaptic dysfunction.
By increasing the expression of SNX27 in the hippocampus of mice with Down syndrome-like symptoms, researchers were able to reduce synaptic and cognitive deficits.
The SNX27 gene encodes for a diverse group of proteins involved in the processes of endocytosis and protein trafficking in cells, according to the Human Gene Compendium.
A lack of SNX27 expression in the hippocampus is associated with the type of cognitive deficit common to Down syndrome patients.
“In the brain, SNX27 keeps certain receptors on the cell surface—receptors that are necessary for neurons to fire properly,” said Dr. Huaxi Xu, Sanford-Burnham professor and senior author of the study, in a press release by the institute. “So, in Down syndrome, we believe lack of SNX27 is at least partly to blame for developmental and cognitive defects.”
While viable drugs and gene-therapies making use of this new research are still years away, this discovery is significant in that it provides a new pathway for pharmaceutical researchers to explore.
It is important to note that this research addresses only the cognitive deficits associated with Down syndrome and not the syndrome as a whole. But it does show that in the search for a potential treatment the solution might not be a single therapy “reversing” the syndrome, but rather a series of treatments that address the symptoms.
by William Tatum