Many women are familiar with period pain - something that's thought to affect around 70 who have endometriosis, a gynaecological problem that affects around 170 million women worldwide, period pain can be far more serious.
"Endometriosis can be a painful and distressing condition that affects a significant number of women in their reproductive years," explains Dr Krina Zondervan of the University of Oxford. "Our study is a breakthrough because it provides the first strong evidence that variations in DNA make some women more likely to develop endometriosis."
Writing in the journal Nature Genetics Dr Zondervan and her team studied the genomes (genetic make-ups) of more than 5,500 women diagnosed with endometriosis and compared them with those of 10,000 healthy volunteers. What they discovered were two genetic variations - one on chromosome 1 and the other on chromosome 7 - that might signal a woman's risk of developing the condition.
In endometriosis cells that are similar to those lining the womb grow on other organs, such as the ovaries and bowel. Some women have minor symptoms and often go undiagnosed, but if you have severe symptoms it can have a devastating effect on your life.
Has a problem like endometriosis affected you?