Chromosome 5

src: public.ornl.gov

Chromosome 5 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 5 spans about 181 million base pairs (the building blocks of DNA) and represents almost 6% of the total DNA in cells. Chromosome 5 is the 5th largest human chromosome, yet has one of the lowest gene densities. This is partially explained by numerous gene-poor regions that display a remarkable degree of non-coding and syntenic conservation with non-mammalian vertebrates, suggesting they are functionally constrained.

Because chromosome 5 is responsible for many forms of growth and development (cell divisions) changes may cause cancers. One example would be acute myeloid leukemia (AML).

Video Chromosome 5

Genes

Number of genes

The following are some of the gene count estimates of human chromosome 5. Because researchers use different approaches to genome annotation their predictions of the number of genes on each chromosome varies (for technical details, see gene prediction). Among various projects, the collaborative consensus coding sequence project (CCDS) takes an extremely conservative strategy. So CCDS's gene number prediction represents a lower bound on the total number of human protein-coding genes.

Gene list

The following is a partial list of genes on human chromosome 5. For complete list, see the link in the infobox on the right.

Maps Chromosome 5

Diseases and disorders

The following are some of the diseases related to genes located on chromosome 5:

src: pulpbits.net

Chromosomal conditions

The following conditions are caused by changes in the structure or number of copies of chromosome 5:

• Cri-du-chat syndrome is caused by a deletion of the end of the short (p) arm of chromosome 5. This chromosomal change is written as 5p-. The signs and symptoms of cri-du-chat syndrome are probably related to the loss of multiple genes in this region. Researchers have not identified all of these genes or determined how their loss leads to the features of the disorder. They have discovered, however, that a larger deletion tends to result in more severe mental retardation and developmental delays in people with cri-du-chat syndrome.

Researchers have defined narrow regions of the short arm of chromosome 5 that are associated with particular features of cri-du-chat syndrome. A specific region designated 5p15.3 is associated with a cat-like cry, and a nearby region called 5p15.2 is associated with mental retardation, small head (microcephaly), and distinctive facial features.

• Familial Adenomatous Polyposis is caused by a deletion of the APC tumor suppressor gene on the long (q) arm of chromosome 5. This chromosomal change results in thousands of colonic polyps which gives the patient a 100% risk of colon cancer if total colectomy is not done.
• Chromosome 5q deletion syndrome is caused by the deletion of the q arm (long arm) of chromosome 5. This deletion has been linked to several blood related disorders including Myelodysplastic syndrome and Erythroblastopenia. This is a different condition than Cri-du-chat which was mentioned above.
• Other changes in the number or structure of chromosome 5 can have a variety of effects, including delayed growth and development, distinctive facial features, birth defects, and other medical problems. Changes to chromosome 5 include an extra segment of the short (p) or long (q) arm of the chromosome in each cell (partial trisomy 5p or 5q), a missing segment of the long arm of the chromosome in each cell (partial monosomy 5q), and a circular structure called ring chromosome 5. A ring chromosome occurs when both ends of a broken chromosome are reunited.

src: www.nature.com

Cytogenetic band

src: circgenetics.ahajournals.org

References

src: slideplayer.com

Further reading

src: www.researchgate.net

External links

• National Institutes of Health. "Chromosome 5". Genetics Home Reference. Retrieved 2017-05-06. 
• "Chromosome 5". Human Genome Project Information Archive 1990-2003. Retrieved 2017-05-06. 

Source of article : Wikipedia