The Genetics of Endometriosis

Genetics plays a major part in the development of endometriosis

Genetics may play a role in the risk of endometriosis. Research is shedding light on how endometriosis may run in families and which genes might be responsible for an increased risk for developing this painful condition.

What Is Endometriosis?

Endometriosis is a condition where tissue similar to the endometrium that lines the uterus (womb) grows in other places like the fallopian tubes and ovaries. Endometriosis affects about 6.5 million women in the U.S. Around the world, endometriosis is estimated to affect up to 10-15% of women of reproductive age.

Symptoms

Women experience endometriosis symptoms in varying levels of severity. Some women have mild enough symptoms that the condition can be left untreated, while others experience more severe symptoms and need to undergo surgical procedures to get relief. 

More, the specific symptoms that women experience are not consistent across the board. Nevertheless, some of the common symptoms indicative of endometriosis are pelvic pain, pain before menstruation, painful intercourse, severe menstrual cramps, infertility, heavy menstrual bleeding, and bladder pain.

Woman experiences pain from endometriosis
 Charday Penn / E+ / Getty Images

Causes and Risk Factors

The exact cause of endometriosis is not known. A person's environment, genetics, and lifestyle are thought to play a significant role in its development. The extent to which each of these three factors contributes is also not known yet.

There are certain risk factors that increase a person's chances of developing endometriosis, and they include

  • Age 
  • Family history
  • Weight 
  • Uterine abnormalities

Familial Risks

Endometriosis runs in families but the exact mechanisms by which it does so are unknown. Research suggests a woman has a 7-10 times greater risk of having endometriosis if a first-degree relative (such as a mother or sister) has it.

With twins, studies estimate that in 75% to 88% cases, when one twin has endometriosis, the other twin has it too. Examining farther out family relationships, a large study conducted in Iceland found that a woman is 50% more likely to have endometriosis if a cousin had the condition.

Finally, women who have first degree relatives with endometriosis may also be more likely to have more severe endometriosis symptoms than those who do not.

Genetic Variations

Studies have also tried to link endometriosis and the severity to which women experience them to specific genes and chromosomes.

One large genome-wide association study was conducted by researchers from medical institutions in Australia, the U.K., and America. It involved 3,194 women diagnosed with endometriosis and 7,060 women without from the U.K. and Australia. A further 2,392 women with endometriosis and 2,271 without, from the U.S. were also studied. 

The study found that:

  • A variant on chromosome 7, called rs12700667, was strongly associated with endometriosis. Women with this variant were around 1.2 times more likely to have endometriosis than women who did not have the variant. They were also almost 1.4 times more likely to have severe endometriosis than women that did not have the variant.
  • Another variant on chromosome 7, called rs7798431, was found more in women with severe forms of endometriosis than those without endometriosis.
  • A third variant, rs1250248, but this time on chromosome 2, was also more common in women with severe endometriosis than those without the condition.

Despite how the study results may seem, having the variants on chromosome 7 or 2 does not mean that you will undoubtedly develop endometriosis. Studies like these simply help improve our understanding of why some people are more likely to develop endometriosis than others.

Another large study published in 2017 analyzed data from over 200,000 women, including 17,045 with endometriosis and 191,596 without the condition. It identified 18 gene variations that are linked to endometriosis. The genes include:

  • WNT4
  •  LINC00339
  • LOC101928043
  • CDC42
  • GREB1
  • RNU6-16P
  • IL1A 
  • CKAP2L
  • CDKN2A
  • MIR331
  • MIR3685
  •  VEZT
  • DNM3OS
  • MIR214
  • MIR3120
  • MIR23B
  •  MIR27B
  • LINC00921

There is currently no genetic test available that can predict whether you will develop endometriosis. Instead, most researchers and scientists firmly assert that endometriosis is a multifactorial condition that's caused by a combination of genetic, environmental, and lifestyle factors.

Supporting these assertions, are the endometriosis studies on identical twins. They show that while genetics is a huge factor in the development of the condition, it doesn't tell the whole story.

Identical (monozygotic) twins have similar genetic profiles. That one twin can have endometriosis, while the other doesn't points to environmental influences in the development of the condition. 

And even solely within the genetic context of the condition, no single genetic variation can predict that you will develop endometriosis. 

Gene Alterations by External Factors

Epigenetic changes are alterations made to the DNA structure that affect how genes are expressed. With epigenetics, the genetic sequence is not altered at all.

An example of an epigenetic change is DNA methylation. It's the process by which a methyl group is added to the DNA molecule. DNA methylation prevents certain genes from being expressed properly.

DNA methylation is influenced by external substances, nutritional deficiencies, and social behavior. The effects of these environmental factors may manifest later in a person's life, or they may be passed onto offspring. Abnormal DNA methylation has been studied as a possible contributor to the development of endometriosis. 

One study suggests that the suppression of progesterone and aromatase genes (which is a major feature of endometriosis) by excessive methylation contributes significantly to the condition's development.

However, unlike DNA mutations, abnormal epigenetic changes can be reversed. Consequently, demethylation agents (DMAs) are being considered as possible treatments for endometriosis.

A Word From Verywell

There's currently no way of determining your risk of developing endometriosis. And while there are no specific ways to reduce your risk of it either, endometriosis is frequently associated with dietary habits and exposure to toxins. And so, eating healthy and limiting exposure to toxins where possible may be helpful.

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