Chromosome 21
Second Chromosome Mapped and Sequenced
This spring, a German- and Japanese-led team of researchers reported that they had completed the mapping of the smallest human chromosome, number 21. This is the second human chromosome to have its DNA
completely deciphered as part of the research team effort funded by the Human Genome Project. Chromosome 22 was reported as fully mapped in December 1999.
Although chromosome 21 is the smallest human chromosome, it may lead to the development of treatment approaches for a multitude of disorders. This chromosome is associated with Down syndrome, leukemia, epilepsy, Lou Gehrig, Alzheimer and various auto-immune diseases.
The mapped sequence was published in the May 5, 2000 issue of the science journal Nature. This chromosome 21 genetic map will now be used to assist other researchers with their challenge to develop improved diagnostic test procedures, and new methods for curing and treating targeted disorders.
A very conspicuous feature of chromosome 21 is that it only contains 225 genes and 59 pseudogenes. Each of these 284 discernible genes are likely to be the controller of a specific protein in a human’s biochemical system.
The research team that mapped and sequenced chromosome 21 consisted of a panel of 62 scientists in Japan, Germany, France, Switzerland, United States of America, and Great Britain.
Their work shows that chromosome 21 contains more than 33 million base pairs of DNA. More exactly, they have sequenced 33,546,361 base pairs of DNA with a high degree of accuracy, predicted by the research team to be more than 99.7% complete and accurate.
The Arc Prevention News primarily focuses on issues aligned with the causal factors of mental retardation or related developmental disorders. It is considered by this editor that the successful mapping of chromosome 21 has the potential to become a valuable tool for investigating the cause of Down syndrome.
Individuals with Down syndrome very frequently are diagnosed to have a heart condition, quite often have developmental abnormalities, repeatedly are described to have dysmorphic features, are habitually reported to have early onset of Alzheimer’s disease, and over and over again have leukemia more frequently than the general public.
They often have problems with their immune system, and on average become involved with a lot of health problems that the average person never faces.
Chromosome 21 is one of the 46 human chromosomes which are made up of 22 pairs of autosomes and one pair of sex-determining X and Y chromosomes.
Down syndrome affects one in 700 live births and is a complex disorder that results when a person is born with an extra, third copy of chromosome 21.
Human Genome Project
http://www.ncbi.nlm.nih.gov/genome/seq
Nature Journal
http://www.nature.com/genomics/
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