Trisomy 21 And Down Syndrome

Trisomy 21 is a result of chromosome non-disjunction in one of the meiotic cell divisions. The non-disjunction event can occur in either parent, but more likely to occur in females. Congenital birth defects are difficult to treat but with the prevalence of Down Syndrome, numerous research projects are being carried out by Down Syndrome Research and Treatment Foundation (DSRTF). Some of the studies are as follows:

Trisomy 21, most commonly known as Down Syndrom is a congenital chromosomal condition in which an individual possesses a complete or partial duplicate of the twenty-first chromosome;whereas, the typical person has a total of 46 chromosomes, a person with Dien Syndrome has 47. This may not seem like a big deal, but this disorder results in varying degrees of mental

The increased risk of Down syndrome in 40 year old women is believed to be caused by errors which can crop up in the eggs’ genetic material as they age (Down-Syndrome Screening: A One-parent test for a Two-parent; The Atlantic 2017). Normally, there are 46 chromosomes in a cell; 23 from the egg and the

When a baby is conceived, the baby receives 23 chromosomes from each parent, equaling 46 chromosomes. Sometimes during this creation a sperm or egg cell can causes that cell to contain 24 chromosomes. When this abnormal cell is included in the conception of a baby, that baby will have 47 chromosomes. The extra chromosome causes Down syndrome. After fertilization; cells start to divide rapidly. Depending on how the cell divides determines what type of Down syndrome the child has. Mosaic Down syndrome is obtained when a cell divides abnormally, creating a string of cells with the extra chromosome. A child with Mosaic Down syndrome has both cells: the normal 46 chromosomes, and the Down syndrome 47 chromosomes. It is believed that babies with Mosaic Down syndrome experience mild symptoms of the disorder.

The likelihood of having a baby born with Down 's syndrome increases with the mother 's age:

In Down syndrome, a person most often inherits two copies of chromosome 21 from the mother and one chromosome 21 from the father for a total of three chromosomes 21. If a baby inherits the chromosome with the extra genes from chromosome 21, then the child will have Down syndrome. About 2% to 4% of people with Down syndrome inherit additional genes from chromosome 21, but not in every cell of the body. These individuals may, for example, have inherited extra genes from chromosome 21 in their bone marrow causing an abnormal increase rate of blood cell production which is the cause of Leukemia Cancer. (Schainman 36)

With any pregnancy the risk of a child having a chromosomal abnormality is increased the later the mother conceives. Women over the age of 35 have been shown to have a higher rate of children who were born with a chromosomal disease (The Gale Encyclopedia of Genetic Disorders, 2010, 98). Some chromosomal abnormalities are more common within this specific age group. They are Down Syndrome (trisomy 21),

     Mosaic Trisomy 21 happens when an egg or sperm come in with an extra copy of chromosome 21, then,

Down syndrome is a chromosomal disorder which occurs in 1 out of every 800 live births ((T. Crandell, C. Crandell & Vander Zanden, 2012, p.81). Most Down patients have a condition called trisomy 21, or 3 copies of the 21st chromosome. This results in an individual with 47 total chromosomes instead of 46 that are normal (Crandell et al., 2012, p.81). This extra chromosome alters typical human

There are over 400,000 individuals with Downs Syndrome: reminder that Down Syndrome is also called Trisomy 21, which is an extra x chromosome on the 22nd chromosome. Given the amount of individuals with Downs Syndrome, it is key that we acknowledge that statistic and foster ways in which we make these individuals lives, and overall quality of life better.

Low muscle tone. Small stature. Upward Slant to the eyes. Single deep crease across the center of the palm. These are a few common physical traits of individuals with Down syndrome. However, every person with Down syndrome is unique and portrays each characteristic at a different degree. Individuals with Down syndrome have an extra chromosome 21. The additional genetic material alters childhood development and causes characteristics associated with the disease. Non-invasive prenatal tests, known as NIPT, analyze the amount of chromosome 21 in the mother’s blood at 10 weeks pregnant. This eugenical testing leads to the extermination of those with Down syndrome. Not only have the abortions rates increased since

This means that babies with down syndrome have an extra chromosome, chromosome 47. Some symptoms of the disorder is physical features such as, flat facial profile, upward slant to eyes, small ears, protruding tongue, and your child will have low muscle tone. Other symptoms include, problems with hearing and vision, being cross eyed, having breathing problems, taking longer than normal to reach childhood milestones and take care of themselves, mild to moderate learning impairment, and growing at a slower rate.

In 1862, John Langdon Down, an English physician, first described those with Down’s Syndrome as “mongoloids” as he believed those with the condition appeared visually similar to people within the Blumenbach’s Mongolian race (Dr Ananya Mandal, 2014). However, in the 1970s, the term Down’s Syndrome replaced mongoloids as it was inaccurate (Dr Ananya Mandal, 2014). During the 20th Century, people with Down’s Syndrome were commonly seperated from society and sent to institutions (Dr Ananya Mandal, 2014). In addition, those with Down’s Syndrome were forcefully sterilized during the 20th Century in an attempt to rid them from the disease (Dr Ananya Mandal, 2014). In 1959, Jérôme Lejeune, a French Pediatrist, discovered that people with Down’s Syndrome have an extra 21st chromosome (Dr Ananya Mandal, 2014). This is where the term Trisomy 21 derrived from which is another name for Down’s Syndrome.

Trisomy 21 is caused by an error in cell division which is called nondisjunction. Nondisjunction results when the embryo gets three copies of chromosome 21 instead of two. This usually occurs at or prior to conception, a pair of 21st chromosomes in either the sperm or the eggs fails to separate. Since this occurs so early on, the extra chromosome is then replicated in every cell of the body. This type of Down syndrome accounts for 95% of cases (“What”). Translocation accounts for about 4% of cases. In this types the total number of chromosomes in the cells remain 46, but an additional full or partial copy of chromosome 21 attaches to another chromosome (usually 14). The presence of the extra full or partial chromosome 21 causes the characteristics of Down syndrome (“What”). Mosaicism or mosaic Down syndrome is a mixture of the two other types. It is characterized by a mixture of two types of cells, some containing the usual 46 chromosomes and some containing 47. The cells that do contain 47 chromosomes contain an extra chromosome 21. This type accounts for only 1% of all the cases of Down syndrome. Some research has shown that individuals with mosaic Down syndrome may have fewer characteristics of Down syndrome that those with other types

Trisomy 21, also known as nondisjunction, means that there is an extra copy of chromosome 21 in the cell and is the most common. Translocation occurs when there are two 21 chromosomes plus an extra piece of chromosome 21 that had attached itself to another chromosome during the division process. Those who have mosaic down syndrome contain an extra chromosome 21 in only some of their cells while others are unaffected. People with mosaic down syndrome tend to have milder physical features and intellectual abilities than those who have trisomy 21 and translocation down syndrome. According to Mark Selikowitz, maternal age is a significant factor in causing trisomy 21. When females are born, all the eggs that a woman will produce are already present. The eggs wait years, some longer than others to be released and it is during the wait period (some 20-40 years) that it is believed errors can occur. On the contrary, man’s sperm does not remain standing therefore less probability for error. Additionally, people with a family history of down syndrome and people who carry the genetic translocation are factors to consider whether the child would be at