Women's Health

Is Endometriosis Genetic? Unraveling a Medical Mystery

Studies are beginning to unravel the mystery of reproductive disorders, and they might be revealing a genetic link in endometriosis.

Part of a clinician's daily work may include counseling patients on the benefits and risks of breast cancer gene testing or the growing number of available prenatal genetic screening tests. Many patients and clinicans alike ask themselves, "Is endometriosis genetic?"

While the genetic link detecting endometriosis has not been determined with certainty, the most popular belief is that this complex disorder with heritable tendencies demonstrates a polygenic/multifactorial inheritance pattern.

Do you discuss the question "Is endometriosis genetic?" routinely with the patient presenting with cyclic dysmenorrhea, dyspareunia and ultrasound findings suggestive of endometriosis? If you do, here is some information you may wish to include in your future counseling.

  • Polygenic inheritance refers to more than one gene controlling a particular characteristic or disease entity. For example, Type II diabetes is an example of polygenic inheritance, whereas Huntington's chorea or Sickle Cell are examples of a monogenic (single gene) disorder.
  • Endometriosis is difficult to study because an invasive test such as laparoscopy or laparotomy, which many patients might neglect to have, is required to cinch the diagnosis. Therefore, the number of women with endometriosis may be underestimated.
  • The disease process may be different depending on the location of the endometriosis. For example, deep infiltrating endometriosis may present very differently than will superficial peritoneal endometriosis.
  • Interestingly, the more severe the endometriosis, the greater the likelihood of a positive family history of endometriosis, according to a recent review in Clinical Obstetrics and Gynecology. This point further supports the premise that endometriosis is inherited.
  • Despite challenges in testing and diagnosing endometriosis, scientists have made progress eliciting more information about the nature of endometriosis. Animal (rhesus monkey) models, epidemiologic studies looking at twins and population-based ancestry studies support a genetic process.
  • With recent rapid advances in molecular biology, the identification and location of causative genes have become possible, and more than one appear to play a role in the disorder.
  • Although endometriosis is not cancer, it shares some of its properties, including local infiltration and angiogenesis. Applying basic cancer research techniques to the study of endometriosis has demonstrated that loss of heterozygosity (LOH), a well-known feature in the development of cancer, also occurs in endometriotic tissue samples.
  • Also, the significantly higher absence of tumor suppressor gene loci in endometriotic tissue samples, compared to controls, further suggests a genetic impact on the development of endometriosis.
  • A premise that a series of cascading genetic events, termed the "multi-hit theory," has developed to explain the process whereby inheriting a mutated gene further increases the risk of other mutations, often resulting in endometriosis.
  • Genomic studies (the study of gene expression) using the DNA microarray technology have further increased the understanding of endometriosis and its linkages to the abnormal expression of crucial genes, particularly genes governing the inflammatory response, the Clinical Obstetrics and Gynecology review points out.
  • Although non-invasive testing and therapies have not yet been realized, these (as well as prevention procedures) may become reality in the future.

When a patient presents with signs and symptoms of endometriosis, you should always ask about family history and discuss the implications of an increased risk if a first-degree relative has been diagnosed with the disorder. Counseling is a prime opportunity to discuss and increase awareness of not only endometriosis but other menstrual as well. A careful exam and an ultrasound are essential to identify any gynecologic pathology — adnexal masses, point tenderness or nodules in the rectovaginal space, for example. A pain and impact questionnaire can help establish the baseline effect on the patient's quality of life. Treatment options, including NSAIDs, contraceptive therapy, GnRH agonists or modified testosterone, should be reviewed. Finally, be sure to create an action plan, with a three-month tracker of symptoms and follow-up.