Researchers from the Genetic Epidemiology Unit, at the University of Cambridge and UCL, found that women's ovarian cancer risk was increased by a fifth if one chromosome carried the variant DNA. Approximately 40 per cent of women in the UK carry one copy.
The study analysed 8,800 women with ovarian cancer and 12,500 without the disease across the UK.
The risk of developing ovarian cancer was increased by 40 per cent for women carrying the variant genetic coding on both chromosomes.
Ovarian cancer is the fifth most common cancer in women in the UK with 130 women diagnosed every week.
Dr Lesley Walker, director of cancer information at Cancer Research UK, said: 'This research could lead to new approaches to treat or prevent the disease.'
Professor Dr Paul Pharoah, who led the study, said that the hunt is on to find the rest of the genes that make up the risk.
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