The risk of a woman getting ovarian cancer has been known to be linked to whether or not her mother had the disease, through mutations in the BRCA genes. However not all cases can be explained this way.
By examining ovarian cancer risk in 189 women and their grandmothers from the Familial Ovarian Cancer Registry at the Roswell Park Cancer Institute in Buffalo, New York, researchers found that the risk of some cases of ovarian cancer was passed down via the X chromosome from the father's side. The study was published in PLOS Genetics.
'Our study may explain why we find families with multiple affected daughters: because a dad's chromosomes determine the sex of his children, all of his daughters have to carry the same X chromosome genes,' said Dr Kevin Eng, first author of the study.
'It's an all-or-none kind of pattern: a family with three daughters who all have ovarian cancer is more likely to be driven by inherited X mutations than by BRCA mutations,' he said.
The researchers then looked for which genes might be causing this association. They searched for changes in the genetic sequence of the X chromosomes of women with ovarian cancer but without a BRCA mutation, and found mutations in a gene called MAGEC3.
'What we have to do next, is make sure we have the right gene by sequencing more families,' said Dr Eng. 'This finding has sparked a lot of discussion within our group about how to find these X-linked families.'
These results could have implications for improving the screening and early detection of ovarian cancer. Dr Catherine Pickworth from Cancer Research UK told the BBC: 'This research suggests that some women's risk of ovarian cancer could be passed down through their father's family, as well as their mother's, due to newly discovered faulty genes. In future, this could help women with a family history of ovarian cancer better understand their risk of developing the disease. This is important because ovarian cancer is often diagnosed at a late stage when it's harder to treat.'