Comparing the genomes of specific cells from the womb lining in women with and without endometriosis, researchers found differences in patterns of DNA methylation, a chemical modification to the DNA that influences which genes are turned on and off.
'The data indicate that the proper interactions of hormones and DNA methylation are critical in normal uterine function,' said the study's lead author, Dr Sahar Houshdaran from the University of California, San Francisco. 'The changes in these interactions that we've seen could play a role in the infertility that often accompanies endometriosis.'
Endometriosis is a chronic disease which, according to Endometriosis UK, affects one in ten women in the UK. In endometriosis, cells that usually line the uterus grow elsewhere in the body, which can result in heavy and painful periods and infertility, among other symptoms. It can be difficult to diagnose and can currently only be definitively determined by a surgical procedure called a laparoscopy.
In this study, researchers compared DNA methylation patterns of endometrial stromal fibroblast cells, which regulate cells in the lining of the uterus, in women with early (stage I) or late (stage IV) endometriosis, and women without the disease. The researchers also looked at the effects on the methylation patterns in these cells after exposure to hormones that regulate the menstrual cycle: progesterone, estradiol (a form of oestrogen), or a combination of the two. They found that DNA methylation patterns were different in each of these conditions.
Because the patterns of methylation differed between the two stages of the disease they studied, the researchers concluded that these may be two distinct disease subtypes rather than progressive stages.
'The findings raise the possibility that differences in methylation patterns could one day be used to diagnose endometriosis and develop customised treatment plans for patients,' said Dr Stuart Moss, of the US National Institute of Child Health and Human Development, which funded the research.
The study was published in PLOS Genetics.