Polymorphisms and endometriosis: a systematic review and meta-analyses.

Identification of 5 genetic polymorphisms as potential biomarkers for endometriosis

Key Points

Highlight:

• Polymorphism in genetics describes multiple forms of a single gene that exists in an individual, or among a group of individuals.
• This article provides a systematic and meta-analysis review of polymorphisms that are associated with endometriosis.

Importance:

• Screening and diagnosis of endometriosis are lengthy and difficult.
• Late diagnosis causes disease progression and becomes harder to treat.
• Therefore, efficient screening tests will be useful for clinical management.

What's done here:

• The study aimed to identify DNA polymorphisms that might predispose to endometriosis, and have the potential to be used as a screening platform.
• The authors performed MEDLINE database searches for publications on DNA polymorphisms in endometriosis.
• Only polymorphisms that have been reported by at least three studies were considered.

Data:

• For endometriosis, 265 different DNA polymorphisms corresponding to 62 genes were cited in at least three publications.
• Original case-control study of endometriosis, association between endometriosis with at least one polymorphism, study to be performed reproductive-age women, and endometriosis confirmed by histology, were inclusion criteria.
• After considering the above inclusion criteria, 28 polymorphisms were suitable for meta-analysis.
• Following five polymorphisms were found significantly associated with endometriosis:
  • Interferon-gamma (IFNG) CA-repeat,
  • Glutathione S-transferase mu 1 (GSTM1) null genotype,
  • Glutathione S-transferase pi 1 (GSTP1) rs1695
  • Wingless-type MMTV integration site family member 4 (WNT4) rs16826658 and
  • Wingless-type MMTV integration site family member 4 (WNT4) rs2235529. 

Limitation:

• This study only focused on polymorphisms studied in at least three different publications, thus novel polymorphisms may be missed.
• Ethnicity was not considered and this may significantly affect polymorphism variability.

Lay Summary

The symptoms of endometriosis are varied among women and include chronic pelvic pain, infertility, and fatigue. There are no reliable blood tests and medical imaging techniques such as MRI and ultrasound are not always satisfactory. The lack of endometriosis-specific symptoms and biomarker assays makes it difficult to diagnose endometriosis. Hence, there is a significant delay in endometriosis diagnosis relative to the time of symptom onset. The delays can be as long as 7-10 years even in countries such as the UK, Austria, Germany and the Netherlands. Laparoscopic excision and histological determination remain the gold standard for diagnosis.

The article by Méar et al. from UFR des Sciences de la Santé Simone Veil, France provided an exhaustive review and meta-analysis of polymorphisms associated with endometriosis. This review was published in the journal  "Human Reproduction Update".

To examine the literature, the authors performed a search on the MEDLINE database for publications on polymorphisms in endometriosis, followed by a text mining approach, to extract gene names. Only genes and polymorphisms that were cited in at least three different publications were included to increase study confidence. The eligibility of each publication was assessed by two investigators. Other inclusion criteria for the meta-analysis are an original case-control study, a reported association between at least one polymorphism and endometriosis, women of reproductive age and a diagnosis of endometriosis as assessed by histology.

Sixty-two genes corresponding to 265 different polymorphisms were cited in at least three publications. Using the meta-analysis selection criteria, only 28 polymorphisms were found to be eligible. Of these 28 polymorphisms, only five were significantly associated with endometriosis: interferon-gamma (IFNG) CA-repeat, glutathione S-transferase mu1 (GSTM1) null genotype, glutathione S-transferase pi1 (GSTP1) rs1695 and two members from wingless-type MMTV integration site family member 4, rs16826658 and rs2235529.

This work contributes to identifying potential genetic screening test for endometriosis. A combination of clinical, genetic, biomarker and family history information to select polymorphisms may be a potential diagnostic tool for symptomatic patients and may reduce the time needed for endometriosis diagnosis.

This work constitutes the first step towards identifying potential markers for a genetic screening test for endometriosis. "Our present findings may enable a better understanding of endometriosis and improve the management of patients with this disease. The combination of these polymorphisms presents the potential for developing a diagnostic tool in primary care for symptomatic patients and should thus decrease the time needed to diagnose endometriosis", the authors concluded.

Research Source: https://www.ncbi.nlm.nih.gov/pubmed/31821471