What is Down Syndrome?
At an incidence of about 1 case per 800 live births, Down syndrome is the most common genetic development disorder. Down syndrome is caused by a trisomy of chromosome 21 (having three copies instead of two copies). This extra copy of chromosome 21 is a result of abnormal cell division of either the sperm or egg cell during development. Down syndrome can be detected 12 to 13 weeks into pregnancy and will cause several abnormalities in affected individuals throughout their developmental years. Down syndrome cannot be cured and symptoms will stay with individuals for the rest of their lives. However, support and treatment options can help affected individuals manage their condition so that they can live happy and fulfilling lives. [1,2,3]
Symptoms
Down syndrome individuals have very distinct physical features that include: a short neck, flattened face and nose, small mouth and ears, upward slanting eyes, and decreased muscle tone.
Other symptoms that aren't readily noticeable include cognitive and behavioral problems such as:
Slow learning
Delayed language and speech development
Impulsive behavior
Increased risk of other health issues (autism, heart/brain abnormalities, etc.)
[2,3]
Diagnosis and Treatment
Screening tests for Down syndrome are a routine part of prenatal care and are usually conducted near the end of the first trimester of pregnancy. A blood test that detects abnormal protein and hormone levels, and a nuchal translucency test that measures the area on the back of the baby's neck are used to estimate the baby's risk of having Down syndrome. Although a single, standard treatment for Down syndrome does not exist, personalized care that focuses on the affected individual's intellectual and physical needs can be implemented. Treatment options could include: speech therapy, physical therapy, and specialized education programs. [1] |
The DYRK1A Gene
Chromosome 21 contains over 200 genes, but there have been several candidate genes identified that play a role in the cognitive impairment that occurs in individuals with Down syndrome. One of these candidate genes is DYRK1A, which encodes for the dual-specificity tyrosine-(Y)-phosphorylation-regulated kinase 1A protein. DYRK1A has received increased attention because it has been associated with cognitive defects in other disorders such as Alzheimer's disease. Because of the extra copy of chromosome 21, DYRK1A is overexpressed in both the fetal and adult periods. DYRK1A plays a role in reduced neurogenesis and premature neuronal differentiation of neuroprogenitor cells, so the overexpression of this gene can lead to several developmental deficits. [1,2,3]
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References
1. Feki, A., & Hibaoui, Y. (2018). DYRK1A Protein, A Promising Therapeutic Target to Improve Cognitive Deficits in Down Syndrome. Brain sciences, 8(10), 187. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6210095/
2. Nguyen, Thu Lan et al. “Correction of cognitive deficits in mouse models of Down syndrome by a pharmacological inhibitor of DYRK1A.” Disease models & mechanisms vol. 11,9 dmm035634. 27 Sep. 2018. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5125364/?report=classic
3. Liu, Y., Lin, Z., Liu, M., Wang, H., & Sun, H. (2017). Overexpression of DYRK1A, a Down Syndrome Candidate gene, Impairs Primordial Germ Cells Maintenance and Migration in zebrafish. Scientific reports, 7(1), 15313. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5681638/
2. Nguyen, Thu Lan et al. “Correction of cognitive deficits in mouse models of Down syndrome by a pharmacological inhibitor of DYRK1A.” Disease models & mechanisms vol. 11,9 dmm035634. 27 Sep. 2018. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5125364/?report=classic
3. Liu, Y., Lin, Z., Liu, M., Wang, H., & Sun, H. (2017). Overexpression of DYRK1A, a Down Syndrome Candidate gene, Impairs Primordial Germ Cells Maintenance and Migration in zebrafish. Scientific reports, 7(1), 15313. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5681638/
Images
Header: https://www.daysoftheyear.com/days/world-down-syndrome-day/
Image 1: https://www.cdc.gov/ncbddd/birthdefects/images/birthdefects-downs-syndrome-500px.jpg
Image 2: https://d3tl80hy6t5toy.cloudfront.net/wp-content/uploads/sites/6/2016/03/23151126/bigstock-Downs-Syndrome-boy-having-spee-67726507-min.jpg
Image 3: https://ladeficienceintellectuelledanslemonde.com/wp-content/uploads/2018/01/GettyImages-685025123-e1516284525623.jpg
Image 4: https://www.ndss.org/
Image 1: https://www.cdc.gov/ncbddd/birthdefects/images/birthdefects-downs-syndrome-500px.jpg
Image 2: https://d3tl80hy6t5toy.cloudfront.net/wp-content/uploads/sites/6/2016/03/23151126/bigstock-Downs-Syndrome-boy-having-spee-67726507-min.jpg
Image 3: https://ladeficienceintellectuelledanslemonde.com/wp-content/uploads/2018/01/GettyImages-685025123-e1516284525623.jpg
Image 4: https://www.ndss.org/
This web page was produced as an assignment for Genetics 564, an undergraduate capstone course at UW-Madison.