Detection of HER-2 gene copy number variations as a molecular marker in the peripheral blood of women with endometriosis in Iranian population: Case-control study

- HER-2 gene copy number significantly increased in Iranian women with endometriosis.
- The measurement of HER-2 oncogene level as a biological marker can be used as a warning sign in women with endometriosis.
- HER-2 gene copy number in endometriosis may have prognostic value for surveying the risk of endometriosis-related cancers.

Endometriosis is a common chronic and polygenic disease among women. Considering the importance of the relationship between endometriosis and the increasing risk of being diagnosed with various cancers among women with endometriosis, it has been demonstrated that genetic factors are clearly involved in half of these cases. The amplification/overexpression of growth factors as a dominant mechanism in developing cancer is of high importance in this progress. HER-2 is one of the main growth factors and contributors in tumorigenesis. The evident role of this biomarker in identifying and curing prevalent cancers among women is an indicator of its possible role in the cancer development process after being diagnosed with endometriosis. Thus, according to the distinctive genetic model of Iran's population, the aim of this study was to explore the relationship between HER-2 gene copy number variations and the risk of endometriosis in Iranian women. In a population-based case-control study conducted in Tehran, in-person interviews were completed for 100 women aged 15-49 years and an equal number of controls frequency-matched to cases by age. All cases were newly diagnosed with endometriosis and all controls were with no laparoscopic evidence of disease between Dec 2014 and Aug 2015. We extracted the genomic DNA from peripheral blood and then HER-2 copy number was detected by real-time PCR. OR and 95% CI were calculated with Mann-Whitney test (P < 0.05 was considered significant). An association was found between endometriosis and HER-2 copy number. Our study showed HER-2 copy number was increased by 2.89 fold (95% CI: 1.58-3.69) in patient group comparing to control group that was statistically significant. Regarding the significant difference between HER-2 gene copy number, it can be concluded that copy number variation, and as a result, variation in levels of HER-2 proto-oncogene expression could serve as a prognostic marker for investigating the chance of endometriosis -related cancers in women with endometriosis.