The 21st chromosome is the smallest human chromosome, and only represents 1.5 percent of DNA in cells. Judging by the list of potential ailments attributed to flaws in this chromosome, it deals with humans development and neurological health.
From the karyotype shown in the assignment, you can clearly tell that there is an unusual case of there being three copies of the 21st chromosome. This of course leads to a genetic disorder called “down syndrome”. According to the National Down Syndrome Society (NDSS), “one in every 691 babies born in the United States is born with down syndrome, making it the most common genetic disorder.”
A person with this genetic defect tend to have delays in regards to physical growth, have a particular set of physical structures—particularly facial ones—, and have a moderate to severe intellectual impairment.
There are several physical structures that are typical of someone with down syndrome. As said on the wikipedia page concerning down syndrome, they are namely: “abnormally small chin, oblique eye fissures on the inner corner of the eyes, poor muscle tone, a flat nasal bridge, a protruding tongue due to small mouth, and an enlarged tongue.” They also tend to have a flat and wide face.
In regards to non-facial structures, they also commonly have a short and very flexible neck, extra space between the large toe and the second, short fingers, as well as a single crease in the palm (also known as a simian crease). Since they also have slower growth, they tend to have a short stature and bowed legs. The average height those suffering from down syndrome would be 5’1 for males and 4’9 for females.
The neurological effects of down syndrome have a very strong effect on cognitive ability. Those with down syndrome tend to have an I.Q. between 50-70 for for “mild” cases to 35-50...