Chromosome 18 (human)
Encyclopedia
Chromosome 18 is one of the 23 pairs of chromosome
s in human
s. People normally have two copies of this chromosome. Chromosome 18 spans about 85 million base pair
s (the building material of DNA
) and represents about 2.5 percent of the total DNA in cells
.
Identifying gene
s on each chromosome is an active area of genetic research. Because researchers use different approaches to predict the number of genes on each chromosome, the estimated number of genes varies. Chromosome 18 likely contains between 300 and 400 genes.
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Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
s in human
Human
Humans are the only living species in the Homo genus...
s. People normally have two copies of this chromosome. Chromosome 18 spans about 85 million base pair
Base pair
In molecular biology and genetics, the linking between two nitrogenous bases on opposite complementary DNA or certain types of RNA strands that are connected via hydrogen bonds is called a base pair...
s (the building material of DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
) and represents about 2.5 percent of the total DNA in cells
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
.
Identifying gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
s on each chromosome is an active area of genetic research. Because researchers use different approaches to predict the number of genes on each chromosome, the estimated number of genes varies. Chromosome 18 likely contains between 300 and 400 genes.
Genes
The following are some of the genes located on chromosome 18:- FECH: ferrochelatase (protoporphyria)
- NPC1NPC1Niemann-Pick disease, type C1 also known as NPC1 is a protein which in humans is encoded by the NPC1 gene.NPC1 was identified as the gene that when mutated, results in Niemann-Pick disease, type C...
: Niemann-Pick disease, type C1 - SMAD4: SMAD, mothers against DPP homolog 4 (Drosophila)
- KC6KC6KC6 is a novel gene located on chromosome 18 at p12.3. It was discovered by Rabinowitz et al. in a study whose aims were finding genes expressed in human cornea and increasing the knowledge of molecular changes in keratoconus. It lies adjacent to the PIK3C3 gene. Its function is unknown so far...
: Keratoconus gene 6, discovery reported in 2005;
Diseases & disorders
The following diseases are some of those related to genes on chromosome 18:- erythropoietic protoporphyriaErythropoietic protoporphyriaErythropoietic protoporphyria is a relatively mild form of porphyria, although very painful, which arises from a deficiency in the enzyme ferrochelatase, leading to abnormally high levels of protoporphyrin in the tissue...
- hereditary hemorrhagic telangiectasiaHereditary hemorrhagic telangiectasiaHereditary hemorrhagic telangiectasia , also known as Osler-Weber-Rendu disease and Osler-Weber-Rendu syndrome, is a genetic disorder that leads to abnormal blood vessel formation in the skin, mucous membranes, and often in organs such as the lungs, liver and brain.It may lead to nosebleeds, acute...
- Niemann-Pick diseaseNiemann-Pick diseaseNiemann–Pick disease refers to a group of fatal inherited metabolic disorders that are included in the larger family of lysosomal storage diseases .-Signs and symptoms:Symptoms are related to the organs in which they accumulate...
Type C - porphyriaPorphyriaPorphyrias are a group of inherited or acquired disorders of certain enzymes in the heme bio-synthetic pathway . They are broadly classified as acute porphyrias and cutaneous porphyrias, based on the site of the overproduction and accumulation of the porphyrins...
- Selective MutismSelective mutismSelective mutism is an anxiety disorder in which a person, most often a child, who is normally capable of speech is unable to speak in given situations, or to specific people...
- Edwards syndrome (Trisomy 18)Edwards syndromeTrisomy 18 is a genetic disorder caused by the presence of all or part of an extra 18th chromosome. It is named after John H. Edwards, who first described the syndrome in 1960...
- Tetrasomy 18pTetrasomy 18pTetrasomy 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. It is characterized by multiple medical and developmental concerns.- Genetic Basis :...
- Monosomy 18pMonosomy 18p18p- is a genetic condition caused by a deletion of all or part of the short arm of chromosome 18. It occurs in about 1 of every 40,000 births.-Nomenclature:The preferred terminology for this condition is 18p-...
- Pitt Hopkins Syndrome 18q21Pitt-Hopkins syndromePitt-Hopkins syndrome is a genetic disorder characterized by mental retardation, wide mouth and distinctive facial features, and intermittent hyperventilation followed by apnea...
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