Endometriosis affects an estimated 6-10 per cent of all women in their reproductive years, at an estimated 170 million women worldwide. It is characterised by the growth of cells similar to those lining the womb on organs in the pelvis, such as the ovaries and bowel. These deposits can cause inflammation and adhesions, and result in pelvic pain as well as infertility in some women.
Why the deposits arise in the first place, and thrive outside the womb, is as yet largely unknown and so this new study by researchers from the International Endogene Consortium which compared the genomes of over 5,500 women surgically diagnosed with the disease from the UK, Australia and the US, and compared them with almost 10,000 healthy volunteers., could be of vital importance. They identified two new genetic variants that increase the risk of developing the disease, particularly moderate-severe stages.
Endometriosis may only cause minor symptoms and go undiagnosed in some women, but in more severe cases debilitating symptoms arise that can have a profound effect on the woman’s life. The only reliable diagnosis is with a pelvic laparoscopy and this one of the reasons why many women can go undiagnosed, or for several years of symptoms to pass before it is identified. Current treatments are usually limited to surgery and hormonal drugs that have numerous side-effects, though natural bio-identical hormones have been successfully used to treat the condition in some cases.
Dr Krina Zondervan, a Wellcome Trust Research Career Development Fellow at the University of Oxford and the study’s Principal Investigator said: “We’ve known for some time that endometriosis is heritable, but until now we have been unable to find any robust genetic variants that influence a woman’s risk of developing the disease. Our study is a breakthrough because it provides the first strong evidence that variations in DNA make some women more likely to develop endometriosis. We now need to understand the effect of these variations on cells and molecules in the body.”
The first is a variant on chromosome 7 believed to be involved in regulating nearby genes, probably those involved in the development of the womb and its lining. The second variant was found on chromosome 1, close to the gene WNT4. This is important for hormone metabolism and the development of the female reproductive tract, especially the ovaries, making it an important biological candidate for involvement in endometriosis.
The results of this study will help towards developing less invasive methods of diagnosis and more effective treatments for endometriosis.