TCN2

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What is the official name of the TCN2 gene?

The official name of this gene is “transcobalamin II.”

TCN2 is the gene's official symbol. The TCN2 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 TCN2 gene?

The TCN2 gene provides instructions for making a protein called transcobalamin (formerly known as transcobalamin II). This protein transports cobalamin (also known as vitamin B12) from the bloodstream to cells throughout the body. Cobalamin is obtained from the diet; this vitamin is found in animal products such as meat, eggs, and shellfish.

During digestion, cobalamin is transported through intestinal cells into the bloodstream. Transcobalamin attaches (binds) to cobalamin when it is released into the bloodstream and transports the vitamin to cells. The transcobalamin-cobalamin complex binds to a receptor on the cell surface, which allows the complex to enter the cell. Transcobalamin releases cobalamin when the complex enters the cell and transcobalamin is broken down.

Within cells, cobalamin helps certain enzymes carry out chemical reactions. Cobalamin plays a role in the processes that produce the building blocks of DNA (nucleotides) and break down various compounds such as fatty acids; these processes are needed for cell growth and division (proliferation) and cellular energy production. Cobalamin's role in these processes is particularly important in the formation of new blood cells and in the nervous system.

How are changes in the TCN2 gene related to health conditions?

transcobalamin deficiency - caused by mutations in the TCN2 gene: More than 20 mutations in the TCN2 gene have been found to cause transcobalamin deficiency. This condition impairs the transport of cobalamin from the bloodstream to cells throughout the body. Affected individuals have difficulty gaining weight and growing at the expected rate (failure to thrive), vomiting, diarrhea, a shortage of all types of blood cells, and neurological problems. Many TCN2 gene mutations lead to a complete or near-complete lack (deficiency) of transcobalamin. Other TCN2 gene mutations result in a transcobalamin protein that cannot bind to cobalamin or a protein that cannot bind to the receptor at the surface of cells. The resulting lack of cobalamin within cells interferes with the functioning of certain enzymes, which impacts many cell activities. As a result, a wide range of signs and symptoms characteristic of transcobalamin deficiency can develop.

Where is the TCN2 gene located?

Cytogenetic Location: 22q12.2

Molecular Location on chromosome 22: base pairs 30,607,082 to 30,627,059

The TCN2 gene is located on the long (q) arm of chromosome 22 at position 12.2.

More precisely, the TCN2 gene is located from base pair 30,607,082 to base pair 30,627,059 on chromosome 22.

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

Where can I find additional information about TCN2?

You and your healthcare professional may find the following resources about TCN2 helpful.

Educational resources - Information pages
Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline: Vitamin B12
Genetic Testing Registry - Repository of genetic test information (1 link)

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

PubMed - Recent literature
OMIM - Genetic disorder catalog
Research Resources - Tools for researchers (4 links)

What other names do people use for the TCN2 gene or gene products?

D22S676
D22S750
TC
TC2
TC-2
TCII
TC II
transcobalamin-2

See How are genetic conditions and genes named? in the Handbook.

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 TCN2?

acids ; cell ; cobalamin ; deficiency ; digestion ; DNA ; failure to thrive ; fatty acids ; gene ;nervous system ; neurological ; proliferation ; protein ; receptor ; vitamin B12

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

References (6 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.