Bad heredity: Xnumx genes that can lead to cancer
'10.04.2021'
Source: Jana delphi
How to understand that you urgently need a genetic test, and prevent the disease.
Since scientists have deciphered the structure of DNA and the rapid development of molecular biology, much has become known about why people develop cancer. A normal cell turns into a tumor cell when certain mutations occur in it. First of all, this concerns genes that regulate the growth and reproduction of cells responsible for “repairing” damaged DNA, writes Jana delphi.
A person acquires many of these mutations throughout his life. Most often, this becomes the cause of cancer. But some “wrong” genes can be inherited from parents.
Breast and ovarian cancer
Breast cancer is one of the most common female cancers. According to some reports, such a malignant tumor will be diagnosed in every twentieth woman during her lifetime. In 5% of cases, the cause is a mutation in the BRCA1 and BRCA2 genes. Normally, they are responsible for repairing damaged DNA.
Mutations BRCA1 and BRCA2 increase the risk of breast cancer by 80%, ovarian cancer by 20-40%. Men with a mutation in the BRCA1 gene have an increased risk of prostate cancer, with a mutation in BRCA2, breast cancer. The male carrier is not likely to become ill, but can transmit the defective gene to her daughter.
The most famous carrier of the BRCA mutation is Angelina Jolie. Breast cancer killed her mother, aunt and grandmother. Upon learning that she inherited the defective genes, the actress decided not to wait for the sad outcome. She agreed to two preventive operations: removal of the mammary glands and ovaries.
Hereditary non-polypous colon cancer (Lynch syndrome)
Colon cancer is among the ten most common cancer diseases. In Russia, it is in fifth place among men and fourth in women. About 3% of malignant tumors develop in people with Lynch syndrome. It occurs due to a mutation in one of the genes of the MMR group responsible for the restoration of damaged DNA.
The disease is inherited according to an autosomal dominant principle, that is, a mutant gene will show its full potential, even if the second gene received from another parent is normal. At the same time, the risk of getting colon cancer is from 80 to 90%. Typically, a tumor occurs at a young age - up to 50 years. At the same time, malignant neoplasms can occur in the stomach, small intestine, uterus, ovaries, renal pelvis, bile ducts, brain, and skin.
Family adenomatous polyposis
Like Lynch’s syndrome, this disease is associated with a dominant gene, so it occurs even if the child received a normal gene from one of the parents. Mutation occurs in the APC gene that regulates cell growth.
By the age of 35, almost all people with familial adenomatous polyposis develop 100 or more polyps in the intestine - growths on the mucous membrane. They quickly turn into malignant tumors. If you do nothing, death from cancer by age 40 is almost guaranteed. The only reliable preventive measure is surgery to remove the colon as soon as the diagnosis is made. Most often, polyps do not manifest themselves before cancer develops. Sometimes they cause blood in the stool.
There is a milder form of the disease when the polyps are smaller than 100, and they appear at a later age. The diagnosis can be established using endoscopic examination of the colon - colonoscopy.
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Lee Fraumeni Syndrome
One of the most important genes that prevent the development of malignant tumors is TP53. It encodes the p45 protein, which is often referred to as the "guardian of the genome." When mutations occur in a cell and it becomes “wrong,” p53 “orders” it to “commit suicide”, starts the process of programmed cell death - apoptosis.
If a child is born with a mutation in such an important gene, he is at a very high risk of various malignant tumors: cancer of the kidneys, adrenal cortex, brain, breast, colon, pancreas, leukemia, melanoma, sarcoma (tumors from connective tissue). Oncological diseases in such people usually develop in childhood or at a young age. The risks of getting sick during life are 85%. Unfortunately, there are no special screening programs that can be used to identify people with the TP53 mutation at an early age. Therefore, prevention is very difficult.
Multiple endocrine neoplasia
This disease occurs when a mutation occurs in the RET gene, which controls the growth, reproduction and development of cells. The main danger of such a genetic defect is a high risk of medullary thyroid cancer. The probability of developing a malignant tumor during life is from 90 to 100%.
Depending on what kind of disorder occurred in the RET gene, thyroid cancer can develop at different ages. Sometimes doctors recommend removing the thyroid gland in early childhood.
Medullary thyroid cancer is a relatively rare cancer, so if diagnosed, this should be the reason for genetic analysis.
When urgently need to check?
The fact that certain malignant tumors are inherited is indicated by some signs:
- The same malignant tumors were diagnosed in many relatives. You should especially be wary if this is a rare type of cancer.
- Family members are diagnosed with cancer at a young age. Most oncological diseases are the lot of older people, because mutations accumulate throughout life. If a person has “wrong” genes from birth, they will most likely manifest themselves much earlier.
- If a person is diagnosed with two or more malignant tumors at once. For example, a woman with a breast and ovarian tumor is more likely to carry the defective BRCA gene.
- If tumors have arisen simultaneously in two paired organs, for example, in both lungs or mammary glands.
