Breast cancer runs in families; however, genetic predisposition (such as being BRCA1 or BRCA2 mutation carriers) explains only a portion of this observation. Epigenetic changes (modifications in the genome that alter gene expression but do not affect the DNA sequence per se) have been shown to also play a role in breast cancer risk.

Researchers from the Columbia University Medical Center in New York have now examined whether a specific epigenetic modification (more specifically, methylation of the DNA) can be associated to breast cancer family history in unaffected women from high-risk breast cancer families. This important work suggests that the levels of DNA methylation in white blood cells from cancer-free women could be one of the factors playing a role in the clustering of breast cancer in families with extensive cancer histories within its members.