The breasts are hormonally-regulated tissues that undergo a series of growth and development cycles throughout life. Breast cancer, the uncontrolled proliferation of cells within the breast, is a progressive and devastating disease that can be fatal. A number of factors contribute to the development of breast cancer, which includes both genetic and environmental factors. Hereditary testing for common genetic mutations allows for genetic screening to identify patients at high risk for developing breast cancer.
BRCA1/2 Testing
BRCA1 and BRCA2 are two related genes strongly linked to the development of breast cancer, says the National Human Genome Research Institute. Under normal conditions, BRCA1/2 act as tumor suppressors--they function to activate DNA damage responses in cells with genetic mutations, allowing the cell to correct its DNA. In cancer, BRCA1 and BRCA2 become inactive, so the cell does not correct its DNA, and instead develops the genetic mutations that allow for cancer progression.
Patients who have inherited a mutant copy of either BRCA1 or 2 have a significantly increased risk of developing breast cancer. A genetic test can identify mutations in either gene, and patients who test positive for BRCA1 or BRCA2 mutation can take preventative measures to protect against breast cancer.
CDH1 Testing
Inherited mutations to the CDH1 gene predispose some individuals to cancer, so CDH1 testing may prove effective to test for inherited breast cancer. CDH1 codes for a protein called E-cadherin, a protein that functions to regulate cell-cell contacts and adhesion. Cell adhesion is important in tumor metastases, since cancer cells gain the ability to break away from the tumor to invade neighboring tissue, leading to metastasis. Cell-cell contacts are also important for regulating the growth of normal breast cells, and dysregulation of contacts can contribute to cancer development.
Inherited mutations to CDH1 have an association with the development of a type of breast cancer that affects the lobules, to develop lobular carcinoma, according to the Genetics Home Reference. Inherited genetic mutations can occur within the CDH1 gene itself, or within regions of the DNA that regulate CDH1 activity. Genetic testing to check for mutations to CDH1 and its regulatory regions identifies patients with a predisposition to inherited lobular carcinoma of the breast.
PTEN Testing
Genetic testing for mutations to the gene PTEN may also identify individuals at risk of developing breast cancer. PTEN is a tumor suppressor gene, which belongs to a large class of proteins called phosphatases. PTEN works to turn off cell survival pathways to allow for cell death when necessary. Mutations to PTEN may allow cells to evade cell death, an essential step mediating breast tumor progression.
The Genetics Home Reference reports that inherited mutations to PTEN are correlated with Cowden syndrome, which can cause breast cancer. Although rare, PTEN testing may provide a hereditary test for breast cancer for patients with a family history of breast tumors or Cowden syndrome.
