Chromosome 18 is one of the 23 pairs of

chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...

s in

human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...

s. People normally have two copies of this chromosome. Chromosome 18 spans about 80 million

base pair A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA ...

s (the building material of DNA) and represents about 2.5 percent of the total DNA in cells.

Genes

Number of genes

The following are some of the gene count estimates of human chromosome 18. Because researchers use different approaches to

genome annotation DNA annotation or genome annotation is the process of identifying the locations of genes and all of the coding regions in a genome and determining what those genes do. An annotation (irrespective of the context) is a note added by way of explanati ...

their predictions of the

number of genes In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

on each chromosome varies (for technical details, see

gene prediction In computational biology, gene prediction or gene finding refers to the process of identifying the regions of genomic DNA that encode genes. This includes protein-coding genes as well as RNA genes, but may also include prediction of other functiona ...

). 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 18. For complete list, see the link in the infobox on the right.

Diseases and disorders

The following diseases are some of those related to genes on chromosome 18: *

Erythropoietic protoporphyria Erythropoietic protoporphyria (or commonly called EPP) is a form of porphyria, which varies in severity and can be very painful. It arises from a deficiency in the enzyme ferrochelatase, leading to abnormally high levels of protoporphyrin in the ...

Hereditary hemorrhagic telangiectasia Hereditary hemorrhagic telangiectasia (HHT), also known as Osler–Weber–Rendu disease and Osler–Weber–Rendu syndrome, is a rare autosomal dominant genetic disorder that leads to abnormal blood vessel formation in the skin, mucous membranes, ...

Niemann–Pick disease Niemann–Pick disease is a group of severe inherited metabolic disorders, in which sphingomyelin accumulates in lysosomes in cells (the lysosomes normally degrade material that comes from out of cells). These disorders involve the dysfunctional ...

type C *

Porphyria Porphyria is a group of liver disorders in which substances called porphyrins build up in the body, negatively affecting the skin or nervous system. The types that affect the nervous system are also known as acute porphyria, as symptoms are ra ...

Selective mutism Selective mutism (SM) is an anxiety disorder in which a person who is otherwise capable of speech becomes unable to speak when exposed to specific situations, specific places, or to specific people, one or multiple of which serving as triggers. ...

* Edwards syndrome (trisomy 18) *

Tetrasomy 18p Tetrasomy 18p is a genetic condition that is caused by the presence of an isochromosome composed of two copies of the short arm of chromosome 18 in addition to the two normal copies of the chromosome. It is characterized by multiple medical and ...

Monosomy 18p 18p- is a genetic condition caused by a deletion of all or part of the short arm (the p arm) of chromosome 18. It occurs in about 1 of every 50,000 births. Signs and symptoms 18p- causes a wide range of medical and developmental concerns. T ...

* Pitt–Hopkins syndrome 18q21 *

Distal 18q- Distal 18q- is a genetic condition caused by a deletion of genetic material within one of the two copies of chromosome 18. The deletion involves the distal section of 18q and typically extends to the tip of the long arm of chromosome 18. Presen ...

(distal deletion) * Proximal 18q- (proximal deletion)

Cytogenetic band

References

* * *

External links

Chromosome18.org

Chromosome18 Registry And Research Society in Europe.
* * {{DEFAULTSORT:Chromosome 18 (Human) Chromosomes (human) *