Genetic factors in endometriosis.




Human Reproduction

Related Monographs

Consumer Data: Endometriosis
Professional Data: Endometriosis


Endometriosis is a disease where the tissue that lines the uterus (endometrial tissue) is found outside of the uterus. The tissue attaches itself on other organs and can spread over a larger area over time. It acts just like the tissue inside the uterus during the monthly menstrual cycle. Endometrial implants, as this tissue is called, may be found anywhere in the body, but are mostly found in the pelvic region.1 Often, these implants are seen on the outside of the ovaries, the fallopian tubes, or the uterus.

The exact cause of endometriosis is unknown, but it occurs almost exclusively in menstruating women. It is rarely seen in women before puberty or after menopause, or in women who are not having monthly periods. One theory that explains how these cells get outside of the uterus is called the transport theory. The transport theory says that endometrial tissue moves to and attaches itself in the abdomen and other areas of the body by something called "retrograde menstruation." This means that the lining of the uterus that is shed at the end of the monthly cycle flows upwards instead of draining out of the body normally. The transport theory also says that the tissue may spread by going through the blood vessel circulation or the lymph nodes.

A recent study investigated the genetic risks of endometriosis in a large population in Iceland. This investigation found that 750 women with endometriosis were significantly more unified in genetics than the corresponding control group. The risk ratio was highest amongst sisters and cousins. The researchers found that cousins affected by this genetic link were likely to be related maternally just as much as paternally. The amount of ancestors needed to complete this study for endometriosis sufferers was notably less that those needed for the control groups. The authors stated that this was the first genetic study to determine the link in endometriosis using a population base. Also, that there is a genetic link that raises the risk for endometriosis in both close and distant relatives.2


1. Sagraves R, Letassy NA. Gynecologic Disorders. In: Koda-Kimble MA, Young LY, et al, eds. Applied Therapeutics, The clinical use of Drugs, 5th ed. Vancouver, Washington: Applied Therapeutics Inc; 1992:70-14 to 70-16.
2. Stefansson H. Genetic factors contribute to the risk of developing endometriosis. Human Reproduction. Mar 2002;17(3):555-559.