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TERC

TERC

Reviewed March 2014

What is the official name of the TERC gene?

The official name of this gene is “telomerase RNA component.”

TERC is the gene's official symbol. The TERC gene is also known by other names, listed below.

Read more about gene names and symbols on the About page.

What is the normal function of the TERC gene?

The TERC gene provides instructions for making one component of an enzyme called telomerase. Telomerase maintains structures called telomeres, which are composed of repeated segments of DNA found at the ends of chromosomes. Telomeres protect chromosomes from abnormally sticking together or breaking down (degrading). In most cells, telomeres become progressively shorter as the cell divides. After a certain number of cell divisions, the telomeres become so short that they trigger the cell to stop dividing or to self-destruct (undergo apoptosis). Telomerase counteracts the shortening of telomeres by adding small repeated segments of DNA to the ends of chromosomes each time the cell divides.

In most types of cells, telomerase is either undetectable or active at very low levels. However, telomerase is highly active in cells that divide rapidly, such as cells that line the lungs and gastrointestinal tract, cells in bone marrow, and cells of the developing fetus. Telomerase allows these cells to divide many times without becoming damaged or undergoing apoptosis. Telomerase is also abnormally active in cancer cells, which grow and divide without control or order.

The telomerase enzyme consists of two major components that work together. The component produced from the TERC gene is known as hTR. The hTR component is an RNA molecule, a chemical cousin of DNA. It provides a template for creating the repeated sequence of DNA that telomerase adds to the ends of chromosomes. The other major component of telomerase, which is produced from a gene called TERT, is known as hTERT. The function of hTERT is to add the new DNA segment to chromosome ends.

Does the TERC gene share characteristics with other genes?

The TERC gene belongs to a family of genes called small miscellaneous ncRNAs (small miscellaneous ncRNAs).

A gene family is a group of genes that share important characteristics. Classifying individual genes into families helps researchers describe how genes are related to each other. For more information, see What are gene families? in the Handbook.

How are changes in the TERC gene related to health conditions?

dyskeratosis congenita - caused by mutations in the TERC gene

At least 11 mutations in the TERC gene have been identified in people with dyskeratosis congenita. This disorder is characterized by changes in skin coloring (pigmentation), white patches inside the mouth (oral leukoplakia), and abnormally formed fingernails and toenails (nail dystrophy). People with dyskeratosis congenita have an increased risk of developing several life-threatening conditions, including cancer and a progressive lung disease called pulmonary fibrosis. Many affected individuals also develop a serious condition called aplastic anemia, also known as bone marrow failure, which occurs when the bone marrow does not produce enough new blood cells.

Some of the TERC gene mutations that cause dyskeratosis congenita result in an absent or unstable hTR molecule; others change the way hTR interacts with hTERT or other components of the telomerase enzyme.

TERC gene mutations lead to telomerase dysfunction, impaired maintenance of telomeres, and reduced telomere length. Cells that divide rapidly are especially vulnerable to the effects of shortened telomeres. As a result, people with dyskeratosis congenita may experience a variety of problems affecting quickly dividing cells in the body such as cells of the nail beds, hair follicles, skin, lining of the mouth (oral mucosa), and bone marrow.

Breakage and instability of chromosomes resulting from inadequate telomere maintenance may lead to genetic changes that allow cells to divide in an uncontrolled way, resulting in the development of cancer in some people with dyskeratosis congenita.

idiopathic pulmonary fibrosis - increased risk from variations of the TERC gene

Several mutations in the TERC gene have been identified in people with the progressive lung disease idiopathic pulmonary fibrosis. Mutations in this gene have been found in cases that run in families (familial pulmonary fibrosis) and, less commonly, in isolated (sporadic) cases. Some individuals with idiopathic pulmonary fibrosis due to TERC gene mutations have family members with other features of dyskeratosis congenita (described above), such as aplastic anemia or cancer.

Mutations in the TERC gene reduce or eliminate the function of telomerase, which allows telomeres to become abnormally short as cells divide. The shortened telomeres likely trigger cells that divide rapidly, such as cells that line the inside of the lungs, to stop dividing or to die prematurely. However, researchers are unsure how shortened telomeres contribute to the progressive scarring and lung damage characteristic of idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis is a complex disease that is probably caused by a combination of genetic and environmental factors. Studies suggest that many affected people with TERC gene mutations may have also been exposed to environmental risk factors, such as cigarette smoke or certain kinds of dust or fumes. It is possible that mutations in the TERC gene increase a person's risk of developing idiopathic pulmonary fibrosis, and then exposure to certain environmental factors can trigger the disease.

other disorders - caused by mutations in the TERC gene

TERC gene mutations have also been found in people with isolated aplastic anemia, a form of bone marrow failure that occurs without the other physical features of dyskeratosis congenita. Researchers suggest that mutations affecting different parts of the telomerase enzyme may account for the absence of these features. Some believe that isolated aplastic anemia caused by TERC gene mutations may actually represent a late-onset form of dyskeratosis congenita in which physical features such as nail dystrophy are mild and may not be noticeable.

Where is the TERC gene located?

Cytogenetic Location: 3q26

Molecular Location on chromosome 3: base pairs 169,764,609 to 169,765,059

The TERC gene is located on the long (q) arm of chromosome 3 at position 26.

The TERC gene is located on the long (q) arm of chromosome 3 at position 26.

More precisely, the TERC gene is located from base pair 169,764,609 to base pair 169,765,059 on chromosome 3.

See How do geneticists indicate the location of a gene? in the Handbook.

Where can I find additional information about TERC?

You and your healthcare professional may find the following resources about TERC helpful.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What other names do people use for the TERC gene or gene products?

  • hTERC
  • hTR
  • SCARNA19
  • small Cajal body-specific RNA 19
  • telomerase RNA
  • telomerase RNA component gene
  • TR
  • TRC3

Where can I find general information about genes?

The Handbook provides basic information about genetics in clear language.

These links provide additional genetics resources that may be useful.

What glossary definitions help with understanding TERC?

anemia ; aplastic anemia ; apoptosis ; bone marrow ; cancer ; cell ; chromosome ; DNA ; enzyme ; familial ; fetus ; fibrosis ; gastrointestinal ; gene ; idiopathic ; leukoplakia ; molecule ; mucosa ; pigmentation ; pulmonary ; risk factors ; RNA ; sporadic ; telomere ; template

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.

See also Understanding Medical Terminology.

References (14 links)

 

The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.

 
Reviewed: March 2014
Published: October 20, 2014