Endometriosis is a condition characterized by the abnormal growth of the endometrium, or tissue lining the uterus, outside the uterus. The endometrium thickens in response to estrogen each month in preparation for a potential pregnancy. If no pregnancy occurs, it breaks down and exits the body as part of the normal menstrual cycle.

The abnormal growths or lesions that develop outside the uterus also thicken in response to estrogen, but there is no route for them to leave the body when they break down. They become trapped, causing pain and risking damage to surrounding tissues.

While the exact cause of endometriosis is not currently known, it is thought to be influenced by a combination of factors that include genetics.

Genes associated with endometriosis

Researchers have identified several genes that might be associated with endometriosis. Many have been discovered by studying the genomes of women with endometriosis and comparing them to the genomes of women without the condition. These are called genome-wide association studies, or GWAS.

For example, one such study identified a gene called vezatin (VEZT) as possibly being involved in the development of endometriosis. VEZT plays several roles in the body, and is thought to be important in enabling a fertilized egg to implant in the uterus. Researchers found that this gene is more active in endometrial lesions compared to normal endometrium. A particular mutation in this gene has been picked up in several GWAS studies and may be involved in triggering the increased activity seen in patients.

Another study, published in Nature, highlighted five regions in the genome that are significantly associated with an increased risk of endometriosis. These regions contain genes involved in sex hormone pathways, such as the estrogen receptor gene ESR1.

A study published in Best Practice & Research: Clinical Obstetrics & Gynaecology in 2018 analyzed the genomes of 1,7045 women with endometriosis. It identified 14 regions in the genome that could increase the risk of endometriosis, and further supported the involvement of previously known candidate genes such as VEZT.

Research is ongoing to identify other potential genetic risk factors that may be associated with endometriosis. Once researchers better understand the genetics of the disease, they may be able to develop better ways to diagnose, treat, and possibly prevent it.

Inheritance and endometriosis

Women whose family members have been diagnosed with endometriosis are not necessarily also going to develop the condition. However, some risk factors associated with endometriosis can be inherited. Research suggests that a woman who has a mother, sister, or daughter with endometriosis is about six times more likely to also develop this disease compared to the general population.

