A new study of the genetics of endometriosis may prove to be a turning point in how the disease is diagnosed and treated. The disease, which affects one in 10 women, has been thought to be the result of a genetic mutation but new evidence indicates it isn’t a mutation in the traditional sense. It’s possible gene expression — the way a gene is switched on or off to produce a specific result — is the link to the development of endometriosis.
Drs. Serdar Bulun and Matthew Dyson, of the Northwestern University Feinberg School of Medicine in Chicago, describe their study as “the first conclusive demonstration” that epigenetics (the switching on and off of gene expression), not mutation, leads to endometriosis.
Endometriosis is a chronic, painful disease affecting women of reproductive age; infertility is often a result. When menstruation occurs, the lining of the uterus is typically shed through the vagina but endometriosis causes the uterine lining tissue to grow outside the uterus in the pelvic cavity. The hormonal fluctuations of the menstrual cycle affect the endometrial tissue outside the uterus.
The researchers say all menstruating primates develop endometriosis, which indicates a “unique evolution behind uterine development and menstruation” that are linked to endometriosis. Retrograde menstruation is thought to be a cause of endometriosis. Retrograde menstruation occurs when uterine tissue is expelled up the fallopian tubes and into the pelvic cavity instead of through the vagina and out of the body.
Most women are thought to experience retrograde menstruation at some point, but in only 10% of women does retrograde menstruation develop into endometriosis. Adding further mystery is how some women experience endometriosis that is not synchronized to their menstrual cycles.
Bulun and Dyson believe the mechanism that causes retrograde menstruation to become endometriosis is the epigenetic switch that controls expression of genes identified as GATA6 and GATA2. During normal menstruation, GATA2 is expressed but expression of GATA6 leads to endometriosis by causing progesterone resistance that induces disease.
The researchers suggest it’s when an “overwhelming number of these altered cells reach the abdominal cavity” that they survive and grow into endometriosis.
If their findings can be confirmed by additional study, the researchers hope that noninvasive tests for endometriosis can be developed. They also suggest genetic testing could identify teenage girls at risk for endometriosis. Once a girl’s risk is confirmed, a regimen of birth control pills may prevent retrograde menstruation from happening in the first place, thereby preventing her risk of developing the disease.
Source: Bulun, Serdar E, et al. “Genome-Wide DNA Methylation Analysis Predicts an Epigenetic Switch for GATA Factor Expression in Endometriosis (abstract).” PLOS Genetics. PLOS. Mar 6, 2014. Web. Mar 14, 2014.