CHEK2 1100delC — moderate breast cancer risk
A CHEK2 1100delC variant has been detected.
You have a CHEK2 gene change that meaningfully raises breast cancer risk, plus smaller increases in some other cancers.
Associated with a moderately increased lifetime risk of breast cancer (~25–30% for women), as well as somewhat elevated risks of colorectal, prostate, and other cancers. Enhanced screening is generally recommended.
If you were assigned female at birth, your lifetime breast cancer risk is around 25–30% — about double the population average. Risk of colorectal, prostate, and a few other cancers is also somewhat raised. Most guidelines recommend earlier and more frequent screening.
What this means
CHEK2 is a checkpoint kinase that helps coordinate DNA damage response. The 1100delC truncating variant produces a non-functional protein. The associated cancer risks are real but more moderate than BRCA1/2 — typically a 2× increase in breast cancer risk for female carriers, smaller increases for several other cancers. Screening recommendations exist (NCCN guidance in the US, similar protocols elsewhere) and meaningfully change outcomes.
CHEK2 is one of the proteins that pauses your cells when their DNA gets damaged, so the damage can be repaired before the cell divides. The 1100delC change produces a shortened, non-working version of the protein. The cancer risks are real but more moderate than those linked to BRCA1 or BRCA2 — roughly double the average breast cancer risk for women, with smaller bumps in colorectal, prostate, and a few other cancers. Screening guidelines exist and starting earlier and more often genuinely changes outcomes.
Caveats
- The risk increase is meaningful but less than BRCA1/2.
- Confirmation testing in a clinical laboratory is essential before acting.
- Cascade testing of first-degree relatives is appropriate.
- Genetic counselling is strongly recommended.
Populations
- Most common in Northern and Eastern European populations