Gene mutation may shed new light on different types of endometriosis

7 February 2012 | by Lone Hummelshoj

Researchers at Yale School of Medicine may have, for the first time, described the genetic basis of endometriosis. The researchers’ discovery of a new gene mutation provides hope for new screening methods – at least for certain types of endometriosis.

Published this week in the online issue of EMBO Molecular Medicine, the study from Hugh Taylor’s team explored an inherited mutation located in part of the KRAS gene, which leads to abnormal endometrial growth and a risk of developing endometriosis.

Whereas endometriosis is suspected to be heritable, the specific genes, or gene, responsible for this disease have not previously been identified. In mice, activation of the KRAS gene causes spontaneous endometriosis, however no mutations in this gene have been identified previously in women with the disease.

KRAS is regulated in part by small RNA molecules called microRNAs. One microRNA called let-7 binds near KRAS and prevents the expression of this gene.

Taylor’s team screened 150 women with endometriosis for a mutation in the site of let-7 binding in the KRAS gene and found that 31% had the mutation as opposed to only 5% in the general population. This mutation leads to greater KRAS expression in endometrial cells which in turn causes them to grow faster, invade more, and to loose some of their ability to respond to progesterone (progesterone resistance being another known factor in endometriosis).

This mutation has been identified previously in women with ovarian cancer, perhaps explaining the possible increased risk of this disease in some women with certain types of endometriosis.

What does all of this mean?

According to Professor Taylor it is expected that these findings will enable genetic testing for disease risk in those women with KRAS mediated endometriosis. The identification of KRAS alterations in endometriosis also suggests new potential therapies that specifically target this pathway.

Professor Hugh Taylor, Yale School of Medicine

This may be a way to identify who among women with endometriosis is at higher risk for cancer. We have not proven that this test can predict cancer yet, however I am hopeful that it will save lives by identifying those at risk once further testing is done prospectively.
As for screening, it will not be present in all endometriosis. There are likely several pathways to get the disease. It will likely work like BRCA testing for breast cancer: if your mother has endometriosis and the mutation then you should be tested. If you have it you are at risk.

said Taylor, who also emphasised that if you do not carry this mutation then you cannot say that you will never get endometriosis, but rather that you might not get this particular type of the disease.

Professor Taylor’s research, and comments, lend fuel to the speculation that what we today call “endometriosis” may be more then one disease – each with its own complex trait. Just like certain cancers.

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