Research shows that endometriosis has a family link because it tends to cluster in families. If you have a first-degree relative (a mother or sister with endometriosis), your risk of having endometriosis is seven to ten times higher than your friend who has no endometriosis in her family. Not only are you more likely to have endometriosis if it runs in your family, but your disease is also likely to be more severe than endometriosis found in women without a family history of the disease. Aren't genetics grand?
This section looks more closely at the possible connections between genetics and endometriosis. This section also helps you check out your own family tree to see whether endometriosis is prevalent.
So why does endometriosis run in families? Today's researchers seek answers to this question. Great leaps in the study of molecular genetics (looking at chromosomes and individual genes) have given researchers new insight into the inheritance of the disease. As with many other diseases, such as cystic fibrosis and diabetes, many subtle changes in the building blocks of the chromosomes can have profound effects.
Researchers have observed and identified the following conditions in endometriosis patients that strengthen the hereditary theory:
i Gene mutations: Some of these mutations affect the survival of detached cells (cells that aren't part of the basic structure of the endometrium and that should die when removed, but don't).
Scientists are finding significant evidence that the endometrial cells in endometriosis have abnormal expression (how they work and perform) of gene products that are responsible for survival, invasion, blood vessel growth, and the like.
Endometrial cells from endometriosis implants show resistance to the normal, programmed cell death (apoptosis) that's found in these cells in the uterus. This resistance, which may be genetic, can improve their survival and allow them to implant.
i Abnormal cell adhesion molecules: These abnormalities may allow cells to grow on surfaces that don't normally accept them. Other enzymes help these cells invade and get a foothold where they don't belong. Progesterone usually suppresses these enzymes, but, for some reason, women with endometriosis don't have this suppressive process. An inherited mutation may be the cause for this change.
Although estrogen is essential for endometrial growth, one enzyme, aro-matase, converts other steroid hormones into estrogen. Normal endome-trial tissue has no detectable aromatase, but endometriosis implants contain this enzyme and show high levels of activity. A genetic abnormality may allow this enzyme and its high activity to exist, leading to high local levels of estrogen that may help the cells grow, invade, and cause the disease.
Another enzyme, 17BHSD type 2, is found in normal endometrial tissue and is activated by progesterone. This enzyme lowers estradiol (the main estrogen produced by the ovary) levels. Because this enzyme isn't in endometriosis glands, higher levels of estradiol and subsequent development of endometriosis can go unchecked.
These findings and additional research point to a genetic or inherited aspect of the disease. Although science can't cure bad genes, knowing the root cause may lead to better treatments.
Carrying migrant endometrial cells from birth
One twist on the hereditary theory of endometriosis states that some women have a hereditary tendency to produce cells predisposed to becoming endometrial cells. This predisposition makes sense because a fetus begins with one cell with the potential to become any and all cells in a human. These stem cells (multipotential cells) can become any part of the body, so the cells of the pelvic cavity (and other places) could possibly transform into endome-trial cells and develop glands and stroma.
But does this only happen with endometrial cells? Does that mean an eyeball could grow in the pelvis? These questions are difficult to answer, and the answers may reside in the way the human body differentiates as it grows from one cell to embryo to fetus to full-term baby. There are other disease states where certain tissues develop in an unusual place (for example, dermoid cysts may have skin, teeth, thyroid tissue, and hair).
These differentiating factors may mistakenly signal cells in the pelvis to become endometrium. After all, this area is close to the uterus and normal endometrium. Unfortunately this signal to an adjacent area doesn't explain the distant forms of endometriosis in the lungs, brain, and even umbilicus — that's a bit far out.
Other possible genetic misfires include
S Faulty cells that react to the local stimulus in the wrong way
S Incorrect signals that cause predisposed cells to become endometrium rather than brain
The bottom line: Abnormalities exist and genetic predispositions to these abnormalities are certainly possible.
Trying to figure out if your family has a history of endometriosis can be hard, particularly if female family members have already gone through menopause. They may not remember all their menstrual symptoms — they're too busy thinking about their current health issues to remember what happened 30 years ago. And many women grew up believing that menstrual pain was just part of life, so they didn't dwell on it.
Of course, anything to do with menstruation, pregnancy, or reproduction wasn't polite dinner conversation, so your questions may turn your mother into a stone face who has no intentions of talking about such topics — especially not with you!
Some inherited traits can definitely signal a tendency to develop endometriosis, though, including your inherited body type. For example, you're more likely to have endometriosis if
^ You're tall and thin. Tall, thin women frequently have shorter menstrual cycles, meaning that they bleed more frequently. They're also more likely to have cervical stenosis, another increased risk for endometriosis.
^ You have red hair. Several studies have shown an association between red hair and endometriosis, although a recent Harvard study showed that only fertile women with red hair were more likely to have endometriosis; infertile redheads weren't.
^ You have certain types of nevi, or moles. Several studies have shown an association between dysplastic (abnormal or unusual) nevi and endometriosis.
^ You're an identical twin, and your twin has endometriosis. An identical twin is more likely than a fraternal twin to have endometriosis if her twin has it.
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