The term CHEK2 1100delC refers to a specific, inherited alteration in a person’s genetic code. Every individual has a gene known as CHEK2, which plays a role in how cells grow and divide. The “1100delC” part of the name describes the precise nature of the genetic variant; a small piece of DNA is missing, or deleted, from the gene.
This change is passed down from a parent to a child and is associated with a higher likelihood of developing certain types of cancer. Understanding this genetic finding is the first step for individuals and their families to consider proactive health measures.
The Role of the CHEK2 Gene
The CHEK2 gene functions as a tumor suppressor, acting as a checkpoint for cell division. Its primary job is to monitor the integrity of our DNA. In a healthy individual, when DNA damage occurs, the CHEK2 gene product, a protein, senses the error and temporarily halts the cell cycle. This pause provides a window of opportunity for other specialized proteins to repair the damage.
This process ensures that genetic errors are not passed on to new cells. If the DNA damage is too extensive to be fixed, the CHEK2 gene can initiate a process called apoptosis, or programmed cell death. This self-destruct mechanism prevents a potentially cancerous cell from multiplying and forming a tumor.
Cancer Risks Associated with the Mutation
The CHEK2 1100delC mutation is most strongly linked with an increased risk for breast cancer. Women with this specific variant have a lifetime breast cancer risk estimated to be between 20% and 30%, compared to the general population’s risk of about 12.5%. This risk is considered moderate—not as high as risks associated with BRCA1 or BRCA2 mutations, but significant enough to warrant specialized medical advice. The effect of the mutation can also be influenced by an individual’s family history of breast cancer.
Beyond breast cancer, this mutation has been associated with other malignancies. Research suggests that the CHEK2 1100delC variant may elevate the risk for developing prostate cancer in men. Some studies have also pointed to a potential link with thyroid cancer, though more research is needed to firmly establish this connection. Having this mutation does not guarantee that an individual will develop cancer, but it does increase the statistical probability over their lifetime.
Updated guidelines from the National Comprehensive Cancer Network (NCCN) in 2024 have shifted the perspective on colorectal cancer risk. Previously, CHEK2 mutations were thought to increase this risk, but current recommendations indicate no increased risk based on the mutation alone. Individuals with CHEK2 mutations are advised to consider their family history and other factors to understand their personal risk for colorectal cancer. A genetics expert can help interpret these risks based on personal and family health history.
Medical Management and Screening Guidelines
For individuals with a CHEK2 1100delC mutation, medical management focuses on enhanced surveillance to detect potential cancers early. National guidelines recommend that women with this mutation begin learning to be aware of changes in their breasts at age 25 and start annual clinical breast exams. Starting at age 40, or earlier depending on family history, yearly mammograms are advised. Additionally, discussion with a doctor about the benefits and risks of yearly breast MRIs should begin between ages 30 and 35.
Risk-reduction strategies should be considered in consultation with a healthcare provider. Medications such as tamoxifen, which can block the effects of estrogen, may be discussed as a way to lower breast cancer risk. Some individuals may also consider a risk-reducing mastectomy, a procedure that lowers breast cancer risk by approximately 90%. The decision is highly personal and based on family history and other factors, as this surgery has not been shown to improve survival.
For other cancer types, screening recommendations are guided by family history. For example, individuals with a strong family history of colorectal cancer may be advised to undergo colonoscopies at an earlier age or more frequently. Similarly, while the risk for prostate cancer may be elevated, specific screening protocols are still being researched. A personalized plan developed with a genetics expert is the best approach to managing these risks.
Inheritance and Family Implications
The CHEK2 1100delC mutation is inherited in an autosomal dominant pattern. This means that if a parent has the mutation, each of their children has a 50% chance of inheriting it, regardless of the child’s gender. It only takes one copy of the altered gene from either parent for the associated cancer risks to increase. This inheritance pattern makes family communication important.
Upon receiving a positive test result for this mutation, individuals are encouraged to share this information with their close blood relatives. Informing relatives provides them the opportunity to pursue their own genetic testing to clarify their status. This process of testing relatives after an initial family member is identified is known as cascade testing.
Understanding the familial nature of this mutation allows relatives to make informed decisions about their own health. If they are found to also carry the CHEK2 1100delC mutation, they can then take proactive steps, such as initiating enhanced cancer screenings. Genetic counseling is a valuable resource for families, helping them understand the test result’s implications and the cascade testing process.