By: Catherine Buren
There are a quarter of a million people in the world living with Down Syndrome. Down Syndrome (DS) is the most common chromosomal disorder that affects the immune system, behavior, craniofacial and skeletal structure, and overall growth and development. DS, also known as trisomy 21, is caused by the presence of a full or partial copy of a third chromosome 21. Recent studies on mouse models have indicated that inhibiting a single gene may be the answer to restoring cognitive function in people affected by Down Syndrome.
An example of a DS karyotype. A trisomy of the 21st chromosome can be seen in the lower left corner. (Source: www2.palomar.edu)
The Background
Current advancements in the treatment of Down Syndrome patients explain the role of the gene Dyrk1a in the cognition deficits expressed in Down syndrome (DS) and Alzheimer’s disease (AD). DS has been tied to AD because of the statistic that more than half of all DS people will develop AD, and a significant number of DS people will die because of this neuro- degenerative condition. In one study, 70% of patients who died during the 5.5-year period during which data was being collected had dementia. It has been shown that disabling a gene in the brain, Dyrk1a, allows scientists to “correct recognition memory deficits in three DS mouse models with increasing genetic complexity... all expressing an extra copy of Dyrk1a” {2}.
The Research
Overexpressed Dyrk1a genes accumulate in the cytoplasm and at the
synapse. Treatment of the three DS models with a genetic inhibitor of Dyrk1a leads to neurotypical function of the gene and corrects the lack of cognitive ability observed in individuals with DS. Brain activity has also been studied, and it was discovered that the brain was more active and productive after therapy with the Dyrk1a inhibitor. These promising results encourage the development of Dyrk1a inhibitors as hopeful pharmaceutical candidates to treat cognitive deficits associated with DS and AD {2}. Therefore, a simple gene therapy may be all that is needed to save people from the progressive neurodegeneration associated with AD and increase the life expectancy of DS people.
An example of a DS Ts65Dn mouse being observed in a variety of behavioral tests to analyze cognitive function. (Source: https://journals.plos.org/plosone/article/figure?id=10.1371/journal.pone.0147733.g001)
Sources:
{1} Alzheimer's Disease in People with Down Syndrome. (n.d.). Retrieved from https://www.nia.nih.gov/health/alzheimers-disease-people-down-syndrom e
{2} “Correction of cognitive deficits in mouse models of Down syndrome by a pharmacological inhibitor of DYRK1A” (Nguyen, et al.)
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