Two genes that appear linked to an aggressive form of ovarian cancer have been identified by U.S. researchers.

The two genes have mutations that appear connected to ovarian clear cells carcinoma, a form of the disease that is frequently resistant to treatment, say researchers at the Johns Hopkins Kimmel Cancer Center. The study was published Wednesday in Science Express.

The scientists identified an average of 20 mutated genes in each case of ovarian clear cell cancer after examining 18,000 genes found in ovarian tumours.

The two genes found to be most common were ARID1A, which normally keeps tumours in check, and PPP2R1A, a gene that helps convert normal cells into cancer cells.

ARID1A mutations were found in 57 per cent of the tumours and PPP2R1A mutations were found in 7.1 per cent.

These two genes had not been previously linked to ovarian cancer, the authors say. Now that the genes have been implicated in the onset of the disease, the discovery could open the door to new treatments.

"They may provide opportunities for developing new biomarkers and therapies that target those genes," Nickolas Papadopoulos, an associate professor of oncology and director of Translational Genetics at the Ludwig Center for Cancer Genetics & Therapeutics at the Kimmel centre in Baltimore, Md., said in a news release.

Ovarian clear cell cancer accounts for about six per cent of ovarian cancers. It often affects women who are younger — age 55 versus age 65 — and is more likely to affect Asian women. The disease usually has a poorer prognosis than other ovarian cancers.

An estimated 2,600 new cases of ovarian cancer will be diagnosed in Canada in 2010, according to the Canadian Cancer Society.