A new study published in the journal Translational Medicine has indicated how endometriosis, a chronic condition that affects women's reproductive organs, causes infertility.
Between 30% and 50% of endometriosis patients are infertile but the precise mechanism of this issue has remained mysterious until now.
The team of South Korean and US researchers studied samples from 21 women who are infertile as a result of endometriosis and found that the inner lining of their uteruses (endometrium) was low in an enzyme, HDAC3.
HDAC3 assists in gene regulation and expression — and when there is a deficiency in this enzyme, the genetic processes needed to support pregnancy in the uterus are disturbed.
When the researchers generated mice with low HDAC3, they found that the mice experienced implantation failure (a fertilised egg failed to implant in the uterine wall).
To successfully begin pregnancy, the fertilised egg must successfully implant in the endometrium and this lining must also structurally change to support the pregnancy (in a process known as decidualization). Mice with low levels of HDAC3 did not show successful completion of either of these processes.
Endometriosis occurs when the cells that line the uterus begin to grow in other parts of the body; this typically occurs in the pelvic canal but can also happen in the tissues and organs outside of this region.
Endometriosis can cause pelvic pain, irregular bleeding during periods, bloating, bowel problems, exhaustion, mood swings, and vaginal muscle spasms.
The authors said that determining the HDAC3 mechanism for fertility opens up a pathway for possible intervention in patients with endometriosis struggling to become pregnant.
Dr Joseph Sgroi, an obstetrician and fertility specialist from the federal council of Royal Australia and New Zealand College of Obstetricians and Gynaecologists, told BuzzFeed News that the research indicates epigenetic medicine could be used to treat infertility in endometriosis patients in the future.
Epigenetic medicine treats disease by switching on or switching off particular genes that regulate functional processes in the body.
Sgroi says that epigenetic research indicates a pathway in research for "future medical therapies that will help women in terms of endometriosis and improving their fertility rates" as well as potentially developing a medical therapy to replace the laparoscopy surgeries required to remove the endometriosis growth from the body.
Sgroi also notes that the study adds to the understanding of implantation in general, whether someone has endometriosis or not, as knowledge of the conditions of the uterus lining required for successful pregnancy is limited.
"Whilst for IVF we're quite apt at being able to select a good-quality embryo, we're not yet able to determine what are the requirements for implantation. To a certain degree we have some knowledge — but not a lot," he said.
It's estimated that 700,000 Australian women have endometriosis — although that figure is thought to be a low estimate due to the number of women with less obvious symptoms of the condition that would not present to clinics.