Dear Dr. Roach: I am a healthy 63-year-old woman. My 29-year-old niece was just diagnosed with metastatic breast cancer. She discovered that she carries a mutation of her CHEK2 gene. Her father, who is my brother, also has the gene. Should I get tested for the gene and should my children be tested? What can you tell me about the CHEK2 gene?
Many genetic mutations have now been associated with breast and other cancers. Probably the best known are the BRCA1 and BRCA2 genes, but CHEK2 is one of many others that increase the risk of developing breast cancer.
CHEK2 is the gene that codes for an enzyme called checkpoint kinase 2, which helps repair DNA. If this enzyme is damaged, cancers are more likely to develop. The most severe mutation is called the 1100delC protein-truncated variant. Six per cent of women with this mutation will develop breast cancer by the age of 49, and 32% will have been diagnosed by the age of 80. Your niece was, sadly, very unlucky. This mutation also doubles the risk of colon cancer.
Women with this gene mutation should undergo more intensive screening for breast, ovarian and colon cancers. Men with this gene mutation, like your brother, are at risk for male breast cancer, as well as stomach, prostate, kidney and thyroid cancers.
Since your brother has the gene, you also had a 50% chance of having it at birth (your risk now is slightly less, since you haven’t had a CHEK2-associated cancer). It is worth talking to your doctor about a referral to a genetic counsellor to consider the consequences of testing for the gene. Knowing you have it is likely to affect how you get screened, and perhaps your childrens’ screening as well. There are treatments to reduce the risk of developing breast cancer in women with this gene mutation.
Dear Dr. Roach: Please tell us the scheme for naming the COVID variants. Why did we skip from the fourth Greek letter (delta) to the 15th (omicron)?
The World Health Agency carefully monitors the strains of coronavirus that are found throughout the world. In addition to the initial virus, variants being monitored (that’s an official category) by the Centers for Disease Control and Prevention include alpha, beta, gamma, epsilon, zeta, eta, iota, kappa, lambda and mu, while the variants of concern are delta and now omicron. The variant theta is no longer considered a “variant of interest.” “Nu” sounded too much like “new” and was thought to be confusing, while “Xi” is a common last name, and so both these letters were skipped, hence “omicron.” The most dangerous coronavirus variants would be called “variants of high consequence” due to ineffectiveness of vaccines, diagnostic tests or approved treatments. Fortunately, there aren’t any of those yet identified.
The more active coronavirus cases there are in the world, the greater the likelihood of more concerning variants being transmitted. That’s why a worldwide commitment to vaccines and other measures to reduce transmission are so important.
Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu