TORONTO — Two new studies suggest women with gene mutations known to raise the risk of breast and ovarian cancer may also have a greater chance of developing heart disease.

And one of the studies suggests a chemotherapy drug commonly used to treat breast cancer may aggravate the problem in some of these women.

The studies are by researchers at Toronto's St. Michael's Hospital, and are published in the journals Nature Communications and the Journal of Biological Chemistry.

Lead researcher Dr. Subodh Verma says the proteins made by the genes BRCA1 and BRCA2 are critical for repairing damage to cellular DNA.

Women with mutations on the genes don't have enough of the protein, and that may be why they develop breast and ovarian cancer.

Verma's team says their work in mice and in tissue from human hearts suggests the proteins are also crucial for repairing damage to the heart, and women with the mutated genes may be at increased risk of heart disease as a result.