Cancer is a common disease. There are 5% to 10% hereditary connections obtained in cancer progression.
This indicates a history of cancer incidence in close relatives increases the risk of cancer of an individual.
Hereditary risk of cancer is occurred due to abnormal genetic mutation passes from one generation to the next generation in a family.
Cancer-affected parents can transfer abnormal genetic mutations to their offspring. Following are some cancers that can hereditary transfer from one generation to the next generation:
- Breast cancer.
- Colon cancer.
- Melanoma (a type of skin cancer).
- Ovarian cancer.
- Pancreatic cancer.
- Prostate cancer.
- Uterine cancer.
Genetic mutations and cancer
Uncontrolled growth of cells is clinically defined as cancer. Some of the genes are mutated because of DNA, the structural and functional units of cells are abnormally changed.
The genetic mutation leads to continuous cell proliferation without taking a break. Thus continuous cell proliferation leads to metastatic tumor formation and turns into cancer.
Genetic mutation can be either hereditary or acquired.
A hereditary gene mutation is transferred to the next generation either through the egg of the mother or sperm of the father of the offspring.
An acquired (somatic) mutation is obtained without involving a hereditary connection.
An acquired mutation passes on to any new cells that are created from that cell. An acquired mutation does not pass on from generation to generation.
The acquired mutation is more common than the hereditary mutation. Most cancers are caused by acquired mutations.
The hereditary mutation is usually inherited through tumor suppressor genes mutations. These are genes that slow down the cell division rate, repair DNA or instruct cells to die at the right time. Every human individual usually has two copies of most of the genes – one from each parent.
If off-spring inherits an abnormal gene copy then abnormal mutation scope increases.
However, one copy of the genetic mutation is not a big issue because another copy of the gene is working correctly.
But in case of both the copies of the gene are stop working (which is most common in acquired mutation), then the gene functioning completely lost.
In this condition, cells growth becomes uncontrolled and cancer occurs. Following gene mutations have increased risk of hereditary cancer development:
BRCA1 and BRCA2 Genetic Mutations
A woman with a BRCA (BReast CAncer) inherit genetic mutation has an increased risk of developing breast and ovarian cancer.
A man with a BRCA inherit genetic mutation has an increased risk of developing breast and prostate cancer.
The PTEN gene leads to Cowden Syndrome. A woman with Cowden Syndrome has a higher risk of breast and uterine cancer development.
The PTEN gene also increases thyroid cancer in both women and men.
Familial Adenomatous Polyposis
The APC gene mutation is caused this syndrome. These genetic mutations increase the risk of colorectal cancer. The soft tissue tumors and brain tumors also increase with such types of genetic mutations.
This is a rare genetic condition that occurs due to abnormal mutation of the TP53 gene that increases the risk of breast cancer, adrenal gland cancer, lung cancer, leukemia, brain tumors, and soft tissue sarcomas (tumors in fat, muscles, nerves, joints, blood vessels, bones or deep skin).
This condition is also called hereditary nonpolyposis colorectal cancer (HNPCC) that increases the risk of colorectal cancer. DNA of MLH1, MSH2, MSH6, or PMS2 is the gene that is abnormally mutated.
Mutation variation can also cause Muir Torre syndrome or Turcot syndrome that increases the risk of skin cancers or brain tumors, respectively.
Multiple Endocrine Neoplasia (MEN)
Two different genes are involved in two types of MEN syndrome. MEN1 is caused by a mutation in the MEN1 gene.
MEN2A and MEN2B are caused by mutations in the RET gene. All these mutations enhance the endocrine cancer risk.
Von Hippel-Lindau Disease
The VHL gene mutation causes abnormal blood vessels growth. This condition is known as hemangioblastomas or angiomas.
This condition increases the risk of kidney cancer and other cancers.
Diagnosis of hereditary cancer
Individuals who have a higher risk to develop hereditary cancer are recommended to consult with a genetic counselor.
A genetic counselor can advise the necessity of genetic testing after evaluating individual family history.
The blood or saliva sample of an individual is tested for genetic testing. Special laboratory testing can detect DNA abnormality.
This testing not only helps to detect the abnormal genetic mutation but also helps to reduce the risk of cancer attack. However, a genetic test does not always provide a yes or no result.
But consultation with a genetic counselor helps to decide the involved risk. Genetic testing is not recommended to children until or unless cancer screening requires for them after a certain age.