CHEK2

CHEK2 is the official symbol for the human gene CHK2 checkpoint homolog. It is located on the long (q) arm of chromosome 22.

Function
The protein coded by this gene is CHK2. This protein prevents the cell from dividing or growing too fast. Thus, the gene is a tumor suppressor gene, because prevents tumors from becoming malignant.

DNA can be damaged by e.g.: CHEK2 responds to genetic damage by producing its protein CHK2, which in turn interacts with other proteins, for example p53. As a result, the cell either stops the cell cycle and therefore its proliferation until the damage is repaired, or it self-destructs (apoptosis). Otherwise, the damage or mutation could make the cell a cancer-cell, developing a tumor.
 * UV-light from the sun
 * other kinds of radiation
 * toxic chemicals
 * exchange of genetic material between chromosomes

Related conditions
A mutation in CHEK2 gene results in decreased DNA-repair, or inability of the cell to undergo apoptosis when it ought to have done so. Thus, a mutation leads to an increased susceptibility to cancer. The following conditions are examples of such cancers.

Breast cancer
A deletion-mutation at position 1100 of the CHEK2 gene is associated with an increased risk of breast cancer, particularly in the European population. The mutation changes the form of the CHK2 protein, making it short and nonfunctional.

Li-Fraumeni syndrome
Most cases of Li-Fraumeni syndrome is caused by a mutation in the TP53 gene. However, this condition has also been identified as a result of CHEK2-mutations in several families.