What is Down syndrome? What are the causes? Is there a treatment?
What is Down syndrome?
Down syndrome is caused when a human has 47 chromosomes instead of the usual 46 chromosomes, and it can lead to physical and mental disabilities. Around 1 in 700 people in the United States are born with Down syndrome, making it the most common genetic disorder. The syndrome results in an extra 21st chromosome and is caused by abnormal cell division. Another name for Down syndrome is trisomy 21, referring to the extra chromosome. This is called nondisjunction, which happens during anaphase 1 or anaphase 2 in meiosis 1 or 2. When the chromosomes do not separate correctly, some cells will have additional chromosomes. There are three types of Down syndrome: trisomy 21, mosaic Down syndrome, and translocation Down syndrome. In trisomy 21, an abnormal cell division causes 95% of the syndrome during the development of gametes, the sperm or the egg cell. As a result, a person will have three copies of chromosome 21. Mosaic Down syndrome occurs when a few cells have an extra copy of chromosome 21, which happens after fertilization. In comparison, Translocation Down syndrome occurs when a portion of chromosome 21 is attached to another chromosome.
What does Down syndrome cause?
There are many physical changes that Down syndrome can cause. It may result in a flatter face, short neck, small features, weaker muscles, and a height below average. Most people with Down syndrome only have specific physical features and no other congenital disabilities. However, these features, including hearing loss, obesity, leukemia, ear infections, and heart defects, are still possible. Mental disorders can include impulsive behavior, poor judgment, and slower learning abilities. Risk factors that will increase the chances of Down syndrome are age, carriers, and already having a child with Down syndrome. As a woman gets over the age of 35 and carries a baby, they are more likely to have a child with Down syndrome. However, the statistics are different. Down syndrome usually appears in children born from parents younger than 35 years old because they tend to have more children. The syndrome is not a sex-linked disorder, and therefore both men and women can be passed down. If a man is a carrier and the woman has Down syndrome, there is a 50% chance of their children having the disorder. If a family already has kids with Down syndrome, it is highly likely they will have another kid with Down syndrome, as it runs in their genetic information. The life expectancy of people affected with Down syndrome has increased tremendously over the past century, as people with Down syndrome are now expected to live to the average age of 50 to 60 years old.
What are the treatments?
Unfortunately, there is currently no definitive treatment or prevention of Down syndrome. However, there are ways parents can test to determine the chances of their children being born with the disorder. There are two different types of tests to identify Down syndrome: screening test and diagnostic test. A screening test can only let a woman and her healthcare provider know if their child has a high risk of developing Down syndrome. The screening test is the safer test but does not provide an exact diagnostic, meaning it can be wrong. The test includes a blood test and an ultrasound. To determine the risk, doctors would look at the amount of fluid behind the baby’s neck. The diagnostic test can determine if the baby has Down syndrome. It would be performed after a screening test, if positive, and would look at the changes in chromosomes. An example is the chorionic villus sampling, which examines the material from the placenta. After a baby is born, doctors can also test for Down syndrome, and they would do a blood test, karyotype, to determine the result. Even though patients with Down syndrome can not be treated, there are many ways that they are supported. Multiple services and organizations will help improve their physical and intellectual skills, as well as skills of speech. There are federal laws requiring states to help families with Down syndrome with therapy programs. Moreover, many public and private schools offer special needs classes which teach at a slower pace.
Thank you for reading!
Written by: Amber Truong
Sources:
“Down Syndrome.” Healthline, the Healthline Editorial Team, www.healthline.com/health/down-syndrome. Accessed 26 Apr. 2021.
“Facts about Down Syndrome | CDC.” Centers for Disease Control and Prevention, www.cdc.gov/ncbddd/birthdefects/downsyndrome.html. Accessed 26 Apr. 2021.
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