Silencing the BRCA1 gene spells trouble
By Nathan Seppa
Since 1994, scientists have known that having a mutated version of the BRCA1 gene greatly heightens a person’s risk of breast cancer. Healthy BRCA1 encodes a cancer-suppressing protein that aids in DNA repair. Scientists have noted a scarcity of the protein in women who have breast cancer but don’t have a family history of the disease or the BRCA1 mutation.
Researchers now report that some of these breast cancer patients nevertheless have an incapacitated BRCA1. Although the gene itself remains intact, a nearby stretch of DNA that switches on the gene has become impaired. The culprit is hypermethylation, a state in which too many methyl groups—hydrocarbon fragments—latch onto a specific DNA region. In some breast cancer patients, hypermethylation disables the control, or promoter, region for BRCA1 and silences the gene such that it can’t direct production of its protein.