Researchers say they’ve found evidence that fathers can pass on genetic mutations via their X chromosome, which can increase the risk of ovarian cancer in their daughters.

Researchers from the Roswell Park Comprehensive Cancer Center in New York published their findings today in the PLOS Genetics medical journal.

The study authors said that from previous research, they knew some women were more likely to develop ovarian cancer if their sister had developed it, rather than if their mother had developed it.

This implied the risk may be from the father’s genetics.

To understand this risk, the researchers used the Familial Ovarian Cancer Registry, housed at the Roswell Park Cancer Institute in New York, to look for clues.

They wanted to know the risk facing women whose paternal grandmothers had developed ovarian cancer. In particular, the researchers wanted to see if the father’s genetics had increased the women’s cancer risk.

They were able to sequence portions of the X chromosome from 186 women with ovarian cancer.

From this analysis, they found evidence that a gene mutation on the X chromosome passed from mother to son to granddaughter might be the cause of an increased risk of ovarian cancer.

“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,” Dr. Kevin Eng, an assistant professor of oncology in Roswell Park’s Department of Biostatistics and Bioinformatics, said in a statement.

The researchers found that women with this gene mutation who developed cancer were diagnosed with the disease nearly seven years earlier than what would normally be expected.

While the BRCA gene mutation is known to increase the risk of breast and ovarian cancer, Eng said that this newly found gene mutation could also explain why some families are more likely to report multiple ovarian cancer cases, but not have the BRCA gene.

However, he said more research is needed to confirm their findings.

“What we have to do next is make sure we have the right gene by sequencing more families,” he said. “This finding has sparked a lot of discussion within our group about how to find these X-linked families. 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.”

Cancer-causing gene mutations

Dr. Avner Hershlag, chief of Northwell Health Fertility in New York, said this study shows how much we still have to learn about how genetics influence cancer risk.

“I think that the genes that so far have been discovered are just the tip of the iceberg,” Hershlag told Healthline. “There are many other genes that are yet to be discovered, and together that group of genes will compromise a much higher percentage of cancer [causes].”

Hershlag said the more information doctors can give patients about their cancer risk, the better they can treat them both before and after a cancer diagnosis.

“The diagnosis of a cancer gene is very important for the patient,” he said. “It means a lot in terms of how they manage the rest of their lives, and in terms of what kind of preventative or prophylactic monitoring they do.”

He explained that this research into cancer-causing gene mutations can also help a new generation before they’re even born.

He pointed out that fertility doctors can test embryos for certain genes in order to ensure that they’re not passed on to the next generation.

“We can diagnose any gene [mutation],” he said. “But if you haven’t identified a gene, we cannot help.”