Have you ever wondered what it is exactly about the extra chromosome 21 that makes cognitive development in children with Down syndrome so challenging? Just this March researchers at the Sanford-Burnham Medical Research Institute published research that may have cracked the code on this one. The researchers have found that a protein called sorting nexin 27, or just SNX27, is reduced in the brains of humans with Down syndrome. SNX27 is a protein that directs important communication proteins to where they need to be inside brain cells. Essentially, if these communication proteins are not properly directed by SNX27, then the brain cells do not communicate as well, and learning and memory are impaired.
Chromosome 21 produces a regulating molecule called miR-155, and so the extra chromosome 21 produces an excess of this regulating molecule. Too much miR-155 indirectly over-regulates SNX27, causing a shortage in SNX27, and consequently, a deficit in cognitive development.
Fortunately, there is still some SNX27 protein in the brain cells of children with Down syndrome, and their brain cells can still communicate! The more any given brain cells communicate, the better those brain cells function together. Brain cells that have impaired communication need better input, and by better we mean more frequent, intense, and specific input. For four decades NACD has been basing its targeted intervention programs for Down syndrome children and adults off this science.
For more information on NACD programs for Down syndrome, please check us out here:
Wang, X., et al. (2013). Loss of sorting nexin 27 contributes to excitatory synaptic dysfunction by modulating glutamate receptor recycling in Down’s syndrome.
Nature Medicine. doi:10.1038/nm.3117