Application of gene amplification by polymerase chain reaction to genetic analysis of molar mitochondrial DNA: the detection of anuclear empty ovum as the cause of complete mole

Challenges in diagnosing hydatidiform moles: a review of promising molecular biomarkers

INTRODUCTION

Hydatidiform moles (HMs) are pathologic conceptions with unique genetic bases and abnormal placental villous tissue. Overlapping ultrasonographical and histological manifestations of molar and non-molar (NM) gestations and HMs subtypes makes accurate diagnosis challenging. Currently, immunohistochemical analysis of p57 and molecular genotyping have greatly improved the diagnostic accuracy.

AREAS COVERED

The differential expression of molecular biomarkers may be valuable for distinguishing among the subtypes of HMs and their mimics. Thus, biomarkers may be the key to refining HMs diagnosis. In this review, we summarize the current challenges in diagnosing HMs, and provide a critical overview of the recent literature about potential diagnostic biomarkers and their subclassifications. An online search on PubMed, Web of Science, and Google Scholar databases was conducted from the inception to 1 April 2022.

EXPERT OPINION

the emerging biomarkers offer new possibilities to refine the diagnosis for HMs and pregnancy loss. Although the additional studies are required to be quantified and investigated in clinical trials to verify their diagnostic utility. It is important to explore, validate, and facilitate the wide adoption of newly developed biomarkers in the coming years.

Genotyping diagnosis of gestational trophoblastic disease: frontiers in precision medicine

Investigations in recent decades have exploited tissue DNA genotyping as a powerful ancillary tool for the precision diagnosis and subclassification of gestational trophoblastic disease. As lesions of gestational origin, the inherited paternal genome, with or without copy number alterations, is the fundamental molecular basis for the diagnostic applications of DNA genotyping. Genotyping is now considered the gold standard in the confirmation and subtyping of sporadic hydatidiform moles. Although a precise diagnosis of partial mole requires DNA genotyping, prognostic stratification according to distinct genetic zygosity in complete moles has recently gained significant clinical relevance for patient care. Beyond hydatidiform moles, DNA genotyping has fundamental applications in the diagnosis or prognostic assessment of gestational trophoblastic tumors, in particular gestational choriocarcinoma. DNA genotyping provides a decisive tool in the separation of gestational trophoblastic neoplasia from non-gestational counterparts/mimics of either germ cell or somatic origin. The FIGO/WHO prognostic scoring scheme requires ascertaining the precise index gestational event and the time interval between the tumor and index gestation, where DNA genotyping can provide highly relevant information. With rapid acquisition of molecular diagnostic capabilities in the clinical practice, DNA genotyping has become closely integrated into the routine diagnostic workup of various forms of gestational trophoblastic disease.

Spermatogonium-Derived Complete Hydatidiform Mole

A complete hydatidiform mole (CHM) is a conceptus with only sperm-derived chromosomes. Here, we report on a CHM with genomic DNA identical to that of the paternal somatic cells. The CHM developed in a woman who had undergone intrauterine implantation of a blastocyst obtained through in vitro injection of a presumed round spermatid into one of her oocytes. The CHM was genetically identical to peripheral white cells of her husband and contained no maternally derived nuclear DNA. We hypothesize that a spermatogonium, rather than a round spermatid, was inadvertently selected for the procedure. The CHM developed into a gestational trophoblastic neoplasia, which resolved after chemotherapy. (Funded by the Japan Society for the Promotion of Science.).

BRCA1 promoter hypermethylation in human placenta: a hidden link with β-hCG expression

Gestational trophoblastic diseases (GTD) are group of pregnancy-related tumors characterized by abnormal levels of 'β-hCG' with higher incidence in South-East Asia, especially India. Our laboratory has reported that wild-type BRCA1 transcriptionally regulates β-hCG in triple negative breast cancers (TNBCs). These factors culminated into analysis of BRCA1 status in GTD, which would emanate into elucidation of BRCA1- β-hCG relationship and unraveling etio-pathology of GTD. BRCA1 level in GTD is down-regulated due to the over-expression of DNMT3b and subsequent promoter hypermethylation, when compared to the normal placentae accompanied with its shift in localization. There is an inverse correlation of serum β-hCG levels with BRCA1 mRNA expression. The effects of methotrexate (MTX), which is the first-line chemotherapeutic used for GTD treatment, when analyzed in comparison with plumbagin (PB) revealed that PB alone is efficient than MTX alone or MTX-PB in combination, in showing selective cytotoxicity against GTD. Interestingly, PB increases BRCA1 levels post-treatment, altering DNMT3b levels and resultant BRCA1 promoter methylation. Also, cohort study analyzed the incidence of GTD at Sree Avittom Thirunal (SAT) Hospital, Thiruvananthapuram, which points out that 11.5% of gestational trophoblastic neoplasia (GTN) cases were referred to Regional Cancer Centre, Thiruvananthapuram, for examination of breast lumps. This has lend clues to supervene the risk of GTD patients towards BRCA1-associated diseases and unveil novel therapeutic for GTD, a plant-derived naphthoquinone, PB, already reported as selectively cytotoxic against BRCA1 defective tumors.

Heterozygous/dispermic complete mole confers a significantly higher risk for post-molar gestational trophoblastic disease

Hydatidiform moles are classified at the genetic level as androgenetic complete mole and diandric-monogynic partial mole. Conflicting data exist whether heterozygous complete moles are more aggressive clinically than homozygous complete moles. We investigated clinical outcome in a large cohort of hydatidiform moles in Chinese patients with an emphasis on genotypical correlation with post-molar gestational trophoblastic disease. Consecutive products of conceptions undergoing DNA genotyping and p57 immunohistochemistry to rule out molar gestations were included from a 5-year period at Beijing Obstetrics and Gynecology Hospital. Patient demographics and clinical follow-up information were obtained. Post-molar gestational trophoblastic disease or gestational trophoblastic neoplasia was determined by the 2002 WHO/FIGO criteria. A total of 1245 products of conceptions were classified based on genotyping results into 219 complete moles, 250 partial moles, and 776 non-molar gestations. Among 219 complete moles, 186 were homozygous/monospermic and 33 were heterozygous/dispermic. Among 250 partial moles, 246 were triploid dispermic, 2 were triploid monospermic, and 2 were tetraploid heterozygous partial moles. Among 776 non-molar gestations, 644 were diploid without chromosomal aneuploidies detectable by STR genotyping and 132 had various genetic abnormalities including 122 cases of various trisomies, 2 triploid digynic-monoandric non-molar gestations, 7 cases of possible chromosomal monosomy or uniparental disomy. Successful follow-up was achieved in 165 complete moles: post-molar gestational trophoblastic disease developed in 11.6% (16/138 cases) of homozygous complete moles and 37.0% (10/27 cases) of heterozygous complete moles. The difference between the two groups was highly significant (p = 0.0009, chi-square). None of the 218 partial moles and 367 non-molar gestations developed post-molar gestational trophoblastic disease. In conclusion, heterozygous/dispermic complete moles are clinically more aggressive with a significantly higher risk for development of post-molar gestational trophoblastic disease compared with homozygous/monospermic complete moles. Therefore, precise genotyping classification of complete moles is important for clinical prognosis and patient management.

A 34-Week Size Uterus with a Complete Hydatidiform Mole: Hook Effect and Severe Anemia with No Vaginal Bleeding

Complete hydatidiform mole is an abnormal pregnancy that usually presents with vaginal bleeding and markedly elevated serum ß-hCG levels. We report a rare case of complete hydatidiform mole occurring in a 16-year-old nulligravid who presented with a 34-week size uterus and a relatively low serum ß-hCG level (722 IU/L)-likely related to the "hook effect"-and severe anemia (hemoglobin: 6.1 g/dL) despite the absence of vaginal bleeding. She also reported right flank pain and was diagnosed with moderate right hydronephrosis owing to the compression exerted by the enlarged uterus on the right ureter. The patient received a total of 6 units of packed red blood cells and was managed by dilation and evacuation followed by serial monitoring of serum ß-hCG levels. Therefore, complete mole can present with symptoms related to an enlarged uterus and severe anemia before the occurrence of vaginal bleeding. It is also important to note that a negative urine pregnancy test or relatively low serum ß-hCG level should prompt repeating the measurement on diluted sample to prevent the "hook effect."

Complete hydatidiform moles are composed of paternal chromosomes and maternal mitochondria

Mitochondrial DNA (mtDNA) and genomic DNA are produced in separate subcellular compartments. Human mtDNA is transmitted via maternal transmission in general. Complete hydatidiform moles (CHMs) represent major trophoblastic diseases that are cytogenetically exceptional because the chromosomal genomic DNA is derived only from sperm cells, making them strikingly different from normal concepti. However, few reports have described the mtDNA-transmission pattern in hydatidiform moles. To evaluate mtDNA transmission in androgenetic CHMs, we compared the sequences of hypervariable regions in 16 trios sets of mtDNAs from maternal, paternal, and villous samples of androgenetic CHMs diagnosed by short tandem repeat-polymorphism analysis. All mtDNAs in androgenetic CHMs were maternally derived, in line with the general human inheritance pattern. Three maternal mtDNAs were heteroplasmic. The heterozygous status of maternal mtDNA was reflected in villous tissue, in which variants status was also heterozygous. CHMs are composed of paternal chromosomes and maternal mitochondria.

Insights into dovetailing GTD and Cancers

Gestational trophoblastic diseases (GTD) encompass a group of placental tumors which mostly arise due to certain fertilization defects, resulting in the over-proliferation of trophoblasts. The major characteristic of this diseased state is that β-hCG rises up manifold than that is observed during pregnancy. The incidence of GTD when analyzed on a global scale, figures out that there is a greater risk in South-East Asia, the reason of which remains unclear. An insight into any possible correlation of GTD incidence with cancers, other than choriocarcinoma, is being attempted here. Also, we review the recent developments in research on the molecular etiopathology of GTD. This review would render a wider eye towards a new paradigm of thoughts to connect GTD and breast cancer, which has not been into the picture till date.

Identification of Metabolic Biomarkers Using Serial 18F-FDG PET/CT for Prediction of Recurrence in Advanced Epithelial Ovarian Cancer

PURPOSE

To evaluate the prognostic value of metabolic parameters derived from serial ¹⁸F fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in patients with advanced epithelial ovarian cancer (EOC).

METHODS

Thirteen patients with advanced EOC who received surgical staging and adjuvant platinum-based combination chemotherapy were prospectively enrolled. ¹⁸F-FDG PET/CT was performed before and after the surgical staging, and after third cycle of chemotherapy. Tumor glucose metabolism at baseline and its change after operation and third cycle of chemotherapy such as changes of maximum standardized uptake values (ΔSUV_max) via ¹⁸F-FDG PET/CT were measured, and assessed regarding their ability to predict recurrence.

RESULTS

Median duration of progression-free survival (PFS) was 25 months (range, 13-34), and although optimal debulking was performed in 10 patients, 5 (38.5%) patients experienced recurrence. Univariate analyses showed significant associations between recurrence and low ΔSUV_max after surgical staging, and low SUV_max change after third cycle of chemotherapy. Multivariate analysis identified low ΔSUV_max after third cycle of chemotherapy as an independent risk factor for recurrence (P=.047, hazard ratio (HR) 16.375, 95% CI 1.041-257.536). Kaplan-Meier survival curves showed that PFS significantly differed in groups categorized based on ΔSUV_max after chemotherapy (P=.001, log-rank test).

CONCLUSIONS

¹⁸F-FDG PET/CT allows for prediction of treatment response by the level of FDG uptake in terms of SUV at baseline and after chemotherapy. The metabolic response measured as ΔSUV_max after third cycle of chemotherapy appears to be promising predictor of recurrence in patients with advanced EOC.

Gestational Trophoblastic Disorders: An Update in 2015

Gestational trophoblastic diseases (GTD) are a group of pregnancy-related disorders representing rare human tumours. They encompass premalignant disorders including complete (CHM), partial hydatidiform mole (PHM), exaggerated placental site (EPS), and placental-site nodule (PSN) as well as malignant disorders (also known as "gestational trophoblastic neoplasia [GTN]") including invasive mole, choriocarcinoma (CC), placenta-site trophoblastic tumour (PSTT), and epitheloid trophoblastic tumours (ETT) (Fig. 1). Originally, GTD develop from abnormal proliferation of trophoblastic tissue and form botryoid arranged vesicles. Premalignant moles are usually treated by suction curettage while persistent and recurrent moles and malignant forms require systemic therapy with methotrexate or combination chemotherapy consisting of etoposide, actimomycin D, methotrexate, vincristine, and cyclophosphamide (EMA-CO). β-human chorion gonadotropin (β-hCG) plays a crucial role in diagnosis and monitoring therapeutic effects. Since the definitive diagnosis cannot be obtained by histology in most cases, persistent or recurrent disease is diagnosed by elevated or persistent serum levels of β-hCG. While curing rates are described to be as high as 98 %, GTD may initially present, recur, or end up as a metastasising systemic disease. This underlines the importance of a regular and consistent follow-up after treatment.

Gestational trophoblastic disease

Gestational trophoblastic disease encompasses a range of pregnancy-related disorders, consisting of the premalignant disorders of complete and partial hydatidiform mole, and the malignant disorders of invasive mole, choriocarcinoma, and the rare placental-site trophoblastic tumour. These malignant forms are termed gestational trophoblastic tumours or neoplasia. Improvements in management and follow-up protocols mean that overall cure rates can exceed 98% with fertility retention, whereas most women would have died from malignant disease 60 years ago. This success can be explained by the development of effective treatments, the use of human chorionic gonadotropin as a biomarker, and centralisation of care. We summarise strategies for management of gestational trophoblastic disease and address some of the controversies and future research directions.

Hydatidiform mole and triploidy: the role of genomic imprinting in placental development

Genomic imprinting, the differential expression of paternal and maternal alleles, is involved in the regulation of embryonic and fetal growth and development. In this review, we focus on the genetics of a disorder caused by a global defect in genomic imprinting, the hydatidiform mole. The ratio between the maternal and paternal genomes is critical in determining the development of both the embryonic and extraembryonic tissues, with an excess of paternally derived chromosomes leading to a complete (no maternal genome) or partial (lower amount of maternal chromosomes) mole. The recent identification and molecular studies in biparental complete moles may yield more insight into the regulation of imprinting during gametogenesis.

Current understandings of the molecular genetics of gestational trophoblastic diseases

Gestational trophoblastic disease (GTD) is a heterogeneous group of diseases characterized by abnormally proliferating trophoblastic tissues. This includes partial and complete hydatidiform moles, invasive mole, choriocarcinoma and placental site trophoblastic tumour. Cytogenetic studies revealed that hydatidiform moles contain either solely (as in complete moles) or an excess (as in partial moles) of paternal contribution to the genome. Genomic imprinting is believed to play a pivotal role in the pathogenesis of hydatidiform moles. However its precise role and mechanism remains poorly understood. Hydatidiform mole carries a potential of malignant transformation. Similar to other human cancers, malignant transformation in gestational trophoblastic tumours is likely a multistep process and involves multiple genetic alterations including activation of oncogenes and inactivation of tumour suppressor genes. In addition, expression of telomerase activity, altered expression of cell--cell adhesion molecules and abnormal expression of matrix metalloproteinases have also been reported in GTD. These represent disruption of the delicate balance and regulation of cellular processes including proliferation, differentiation, apoptosis and invasion. The significance of these alterations in the pathogenesis and malignant transformation of gestational trophoblastic diseases is reviewed in this paper.

Molar pregnancy and risk for cancer in women and their male partners

OBJECTIVE

It was our aim to evaluate the hypothesis that molar pregnancy is a marker of increased risk for cancer.

STUDY DESIGN

This was a nationwide cohort study of 1520 women, identified from the Danish National Register of Patients, in whom a molar pregnancy was diagnosed during the period 1977-1992 and of 1295 male partners of these women, traced in the Danish Central Population Register.

RESULTS

Linkage of the female roster with the Danish Cancer Registry through 1994 revealed 19 cases of gestational choriocarcinoma, whereas 0.04 was expected from the rates for the general population. Twenty cases of cancers of other types were observed with 24.9 expected (standardized incidence ratio, 0.8; 95% confidence interval, 0.5-1.2), but no specific type of cancer other than gestational choriocarcinoma occurred at a rate significantly different from that expected. Among the 1295 male partners notified in the Central Population Register, a total of 22 cancers were observed with 21.9 expected (standardized incidence ratio, 1.0; 95% confidence interval, 0.7-1.5).

CONCLUSION

Molar pregnancy is not associated with an increased risk for cancer other than gestational carcinoma.

Role of imprinting in abnormal human development

Parental-specific differences in the expression of certain genes (imprinting), may be implicated in the pathogenesis of anomalous gestations, but only a minority manifest themselves as malformation syndromes. Delayed or lost gestations are much more frequent sequelae, as are those disorganized to such an extent that they are usually classified as neoplastic rather than developmental processes. Expression levels from imprinted loci are dependent not only on the number of genomic alleles present and their structural integrity, but also on their specific parental origin. Anomalous expression of imprinted genes during development is sometimes caused by imbalanced representation of maternal and paternal contributions, 'uniparental disomy'. Uniparental parthenogenetic or androgenetic gestations form ovarian teratomas or complete hydatidiform moles, respectively--examples of an arrested developmental program. Uniparental disomy of individual chromosomes or portions thereof has been associated with developmental delay or gestational loss. The phenotype of hemizygous mutation or deletion of imprinted genes is modified by the parental origin of the mutant copy, with dichotomous syndromes defined by parental inheritance, as in the Prader-Willi and Angelman syndromes. Lastly, failure of the imprinting process itself, 'loss of imprinting', may quantitatively alter expression levels of normally imprinted transforming or tumor-suppressing genes, thereby increasing risk for developmental tumors such as Wilms' tumor or choriocarcinoma.

The homozygous complete hydatidiform mole: a unique resource for genome studies

The most frequent type of complete hydatidiform mole is a 46, XX homozygote formed by the fertilization of an empty ovum by a single haploid sperm that later duplicates its chromosomes to give a diploid tumor. The homozygous nature of these complete hydatidiform moles makes them unique resources for human genome studies. They can serve as homozygous controls in the development of single nucleotide polymorphism (SNP) markers and provide a way to obtain long-range haplotypes that are useful in population studies. The use of a homozygous control makes it possible to estimate the allele frequencies of the SNP markers in any population by sequencing pooled DNA samples. In this report, we present evidence of homozygosity of a complete hydatidiform mole using 20 diallelic markers distributed across the genome. Furthermore, its usefulness as a homozygous control in SNP development and as a resource for long-range haplotype determination is demonstrated using 11 newly discovered loci in the BRCA2 region on chromosome 13q12-q13.

Gestational trophoblastic disease

BACKGROUND

Gestational trophoblastic disease consists of a group of interrelated diseases, including molar pregnancy, placental site trophoblastic tumor, and choriocarcinoma.

METHODS

Advances in the diagnosis and management of gestational trophoblastic diseases over the past 5 years were reviewed.

RESULTS

Molar pregnancy is now categorized as complete or partial on the basis of gross and microscopic histopathologic and karyotypic findings. Early detection of persistent gestational trophoblastic tumor (GTT) depends on careful postmolar gonadotropin follow-up and consideration of the diagnosis for any woman of reproductive age with unexplained gynecologic and/or systemic symptoms. Triple therapy with methotrexate, actinomycin D, and cyclophosphamide was once the preferred treatment for patients with high risk metastatic GTT but induced remission in only about 50%. Treatment with etoposide, methotrexate, actinomycin D, cyclophosphamide, and vincristine is now the preferred regimen for treatment of high risk metastatic GTT and has been shown to induce remission in about 70% of patients.

CONCLUSIONS

Important advances have been made in the diagnosis and treatment of patients with gestational trophoblastic disease, and patients can be reassured that they can anticipate normal reproductive functioning.

Distinctive flow histogram pattern in molar pregnancies with elevated maternal serum human chorionic gonadotropin levels

BACKGROUND

Flow cytometric analysis of trophoblastic tissue has shown that most partial hydatidiform moles (PMs) are triploid, whereas most complete moles (CMs) are diploid or tetraploid. Ploidy analysis can support a diagnosis of CM or PM. However, in some cases, a precise diagnosis cannot be rendered.

METHODS

This study examined DNA flow histograms in 86 cases of histologically diagnosed moles and nonmoles to identify patterns specific to moles to eliminate indeterminate diagnoses. Forty hydropic abortions, 17 CMs, and 29 PMs were analyzed, and results were correlated with microscopic appearance and maternal serum human chorionic gonadotropin (HCG) levels.

RESULTS

Analysis of nondiploid histologic moles in which the initial maternal serum HCG level was greater than 150,000 mIU/ml showed similar histograms in 12 of 14 cases. In these 12 specimens, a distinct aneuploid peak could not be delineated from multiple cell populations between the G0/G1 and G2/M or G0/G1diploid and G0/G1aneuploid peaks. This commonly appeared as a slope rising toward the tetraploid region. S-phase fraction values showed a trend toward higher values in the moles versus nonmoles, but the difference was not statistically significant.

CONCLUSIONS

This sloping histogram pattern may reflect progression from a single aneuploid to multiple aneuploid populations. Its statistically significant correlation (P < 0.001) with high maternal serum HCG values suggests the presence of a highly metabolically active population of aneuploid trophoblast. Because it appears specific to nondiploid moles, recognition of the pattern will aid in the distinction of mole from hydropic spontaneous abortion.

Molar villous fluid suppresses mononuclear cell cytotoxicity

Complete molar pregnancy tissue is an allograft to the mother because all molar chromosomes are of paternal origin. Interactions between molar tissue and the maternal immune system may be important in the natural history of complete molar pregnancy. Molar villous fluid (MVF) has previously been demonstrated to suppress both mitogen and interleukin-2-induced T lymphocyte proliferation. The current study was undertaken to evaluate the potential effect of MVF on the cytotoxic activity of mononuclear cells (MNC) and lymphokine-activated mononuclear cells (LA-MNC). Sera and molar villous fluid were obtained from four women at the time of molar evacuation. K-562 erythroblastoid cells were used as target cells for MNC-mediated lysis, and JEG-3 choriocarcinoma cells were used as targets for LA-MNC-mediated lysis in a 51Cr release assay. Relative to patient sera, all MVF tested significantly inhibited both MNC and LA-MNC lysis of target cells (48.3 and 91% mean inhibition, respectively; P < 0.05). This study provides additional evidence that molar gestational tissue produces factor(s) that suppress maternal immunologic responses. Potential therapies may become available to reduce or eliminate the immunosuppressive effects of molar gestations resulting in a more favorable clinical outcome in patients with complete molar pregnancy and postmolar gestational trophoblastic tumors.