P–553 Women with molar pregnancies have a genetic susceptibility to aneuploid miscarriages

Study question

What causes non-molar miscarriages in women with one hydatidiform mole (HM)?

Summary answer

We found a higher rate of aneuploidies in the non-molar miscarriages of women with HM than in those from women with sporadic or recurrent miscarriages.

What is known already

Women with hydatidiform moles have higher rates of miscarriages and women with recurrent miscarriages have higher rates of moles than women from the general population.

Study design, size, duration

We retrieved archived formalin-fixed paraffin embedded tissues from non-molar miscarriages of patients with one HM and analyzed them for the presence of aneuploidies using single nucleotide polymorphism (SNP)-microarray. We next determined the meiotic origin of the aneuploidies by genotyping the aneuploid non-molar miscarriages along with the parental genomes using microsatellite markers.

Participants/materials, setting, methods

All participants and some of their partners provided written consent to participate in our study, agreed to a blood draw for genotyping analysis, and agreed for us to retrieve their molar and non-molar tissues from various histopathology laboratories for research purposes.

Main results and the role of chance

We demonstrate for the first time that patients with an HM and miscarriages are at higher risk for aneuploid miscarriages [83.3%, 95% confidence interval (CI): 0.653–0.944] than women with sporadic (51.5%, 95% CI: 50.3–52.7%, p value = 0.0003828) or recurrent miscarriages (43.8%, 95% CI: 40.7–47.0%, p value = 0.00002). Genotyping the aneuploid miscarriages and the parental genomes demonstrated that most of the aneuploidies originated from errors in maternal meiosis I or II.

Limitations, reasons for caution

We were able to retrieve only 30 non-molar miscarriages from women with one HM for analysis. Expanding such analysis to a larger and independent cohort of miscarriages from such patients will be important to validate our observations.

Wider implications of the findings: Our data suggest common genetic female germline defects predisposing to HM and aneuploid non-molar miscarriages in some patients.

Trial registration number

Not applicable

Comprehensive analysis of 204 sporadic hydatidiform moles: revisiting risk factors and their correlations with the molar genotypes

Hydatidiform mole (HM) is an aberrant human pregnancy characterized by excessive trophoblastic proliferation and abnormal embryonic development. HM has two morphological types, complete (CHM) and partial (PHM), and non-recurrent ones have three genotypic types, androgenetic monospermic, androgenetic dispermic, and triploid dispermic. Most available studies on risk factors predisposing to different types of HM and their malignant transformation mainly suffer from the lack of comprehensive genotypic analysis of large cohorts of molar tissues combined with accurate postmolar hCG follow-up. Moreover, 10-20% of patients with one HM have at least one non-molar miscarriage, which is higher than the frequency of two pregnancy losses in the general population (2-5%), suggesting a common genetic susceptibility to HM and miscarriages. However, the underlying causes of the miscarriages in these patients are unknown. Here, we comprehensively analyzed 204 HM, mostly from patients referred to the Quebec Registry of Trophoblastic Diseases and for which postmolar hCG monitoring is available, and 30 of their non-molar miscarriages. We revisited the risk of maternal age and neoplastic transformation across the different HM genotypic categories and investigated the presence of chromosomal abnormalities in their non-molar miscarriages. We confirm that androgenetic CHM is more prone to gestational trophoblastic neoplasia (GTN) than triploid dispermic PHM, and androgenetic dispermic CHM is more prone to high-risk GTN and choriocarcinoma (CC) than androgenetic monospermic CHM. We also confirm the association between increased maternal age and androgenetic CHM and their malignancies. Most importantly, we demonstrate for the first time that patients with an HM and miscarriages are at higher risk for aneuploid miscarriages [83.3%, 95% confidence interval (CI): 0.653-0.944] than women with sporadic (51.5%, 95% CI: 50.3-52.7%, p value = 0.0003828) or recurrent miscarriages (43.8%, 95% CI: 40.7-47.0%, p value = 0.00002). Our data suggest common genetic female germline defects predisposing to HM and aneuploid non-molar miscarriages in some patients.

Microsatellite DNA Genotyping and Flow Cytometry Ploidy Analyses of Formalin-fixed Paraffin-embedded Hydatidiform Molar Tissues

Hydatidiform mole (HM) is an abnormal human pregnancy characterized by excessive trophoblastic proliferation and abnormal embryonic development. There are two types of HM based on microscopic morphological evaluation, complete HM (CHM) and partial HM (PHM). These can be further subdivided based on the parental contribution to the molar genomes. Such characterization of HM, by morphology and genotype analyses, is crucial for patient management and for the fundamental understanding of this intriguing pathology. It is well documented that morphological analysis of HM is subject to wide interobserver variability and is not sufficient on its own to accurately classify HM into CHM and PHM and distinguish them from hydropic non-molar abortions. Genotyping analysis is mostly performed on DNA and tissues from formalin-fixed paraffin-embedded (FFPE) products of conception, which have less than optimal quality and may consequently lead to wrong conclusions. In this article, detailed protocols for multiplex genotyping and flow cytometry analyses of FFPE molar tissues are provided, along with the interpretation of the results of these methods, their troubleshooting, and integration with the morphological evaluation, p57^KIP2 immunohistochemistry, and fluorescence in situ hybridization (FISH) to reach a correct and robust diagnosis. Here, the authors share the methods and lessons learned in the past 10 years from the analysis of approximately 400 products of conception.