Repetitive complete hydatidiform mole can be biparental in origin and either male or female

Gestational trophoblastic disease: STR genotyping for precision diagnosis

INTRODUCTION

Gestational trophoblastic disease (GTD) encompasses a constellation of rare to common gynecologic conditions stemming from aberrant gestations with distinct genetic backgrounds and variable degrees of trophoblast proliferation of either neoplastic or non-neoplastic nature. GTD is categorized into hydatidiform moles and gestational trophoblastic neoplasms, and their clinical outcomes vary widely across different subtypes. Prompt and accurate diagnosis plays a pivotal role in the effective management and prognostication of patients. Short tandem repeats (STRs) are repetitive DNA sequences dispersed throughout the human genome and inherit a tremendous genetic polymorphism among individuals. Widely recognized for its applications in forensic identity and paternity testing, the relevance of STR genotyping in the diagnosis of GTD has emerged as an essential ancillary test in the classification and management of GTD of both non-neoplastic hydatidiform moles and gestational trophoblastic tumors.

AREA COVERED

This review discusses fundamental principles, laboratory operation, and diagnostic interpretations of STR genotyping in the context of diagnosis and differential diagnosis of GTD. PubMed was searched for all references up to 2024.

EXPERT OPINION

STR genotyping is the gold standard in the diagnosis and subclassification of hydatidiform moles and has an important application in diagnostic workup and risk stratifications of gestational trophoblastic tumors as well.

Trophoblastic disease and choriocarcinoma

Gestational trophoblastic disease (GTD) is a group of diseases associated with pregnancies that demonstrate abnormal development of trophoblastic cells. GTD includes hydatidiform moles (HM) that may continue to further develop into gestational trophoblastic neoplasms (GTN), such as choriocarcinoma (CC). Gestational CC is a malignant mass development that may arise from HM, from other (normal) pregnancies or from other gestational events (such as ectopic pregnancies). The aim of this review is to outline current understating of the genetics and epigenetics of GTD and gestational CC and the link between the two diseases.

Successful Management of Persistent Gestational Trophoblastic Neoplasia: A Comprehensive Review and Case Analysis

Gestational trophoblastic disease comprises hydatidiform mole (HM) (complete or partial) and gestational trophoblastic neoplasia (GTN). Complete and partial moles have different karyotypes, gross and microscopic histopathology, clinical presentation, prognosis, and chances of progress to GTN. Ultrasonography (USG) and human chorionic gonadotropin (hCG) quantification are commonly used to diagnose molar pregnancy and further follow-up until resolution. Our case reports two patients, one with a complete mole and another with a partial mole, who were evaluated and followed up with serial beta hCG as per protocol and were found to have persistent disease and referred for chemotherapy until complete resolution. Fifteen to 20% of the patients with complete moles and about 1-5% of patients with partial moles developed GTN, which is primarily invasive. Hence, proper follow-up and chemotherapy assure 100% curability.

Chimeric Singleton Placenta Comprising Placental Mesenchymal Dysplasia and Complete Hydatidiform Mole with Live Birth and Postpartum Diagnosis of Gestational Trophoblastic Neoplasia

INTRODUCTION

Placental mesenchymal dysplasia (PMD) is a benign lesion that is often misdiagnosed as complete (CHM) or partial hydatidiform mole. PMD usually results in live birth but can be associated with several fetal defects. Herein, we report PMD with CHM in a singleton placenta with live birth.

CASE PRESENTATION

A 34-year-old gravida 2, para 1, living 1 (G2P1L1) woman was referred on suspicion of a molar pregnancy in the first trimester. Maternal serum human chorionic gonadotrophin levels were increased during early pregnancy, with multicystic lesions and placentomegaly observed on ultrasonography. Levels decreased to normal with no fetal structural abnormalities observed. A healthy male infant was delivered at 34 gestational weeks. Placental p57KIP2 immunostaining and short tandem repeat analysis revealed three distinct histologies and genetic features: normal infant and placenta, PMD, and CHM. Gestational trophoblastic neoplasia was diagnosed and up to fourth-line chemotherapy administered.

CONCLUSION

Distinguishing PMD from hydatidiform moles is critical for avoiding unnecessary termination of pregnancy. CHM coexisting with a live fetus rarely occurs. This case is unique in that a healthy male infant was born from a singleton placenta with PMD and CHM.

Advances in the diagnosis and early management of gestational trophoblastic disease

Gestational trophoblastic disease describes a group of rare pregnancy related disorders that span a spectrum of premalignant and malignant conditions. Hydatidiform mole (also termed molar pregnancy) is the most common form of this disease. Hydatidiform mole describes an abnormal conceptus containing two copies of the paternal genome, which is classified as partial when the maternal genome is present or complete when the maternal genome is absent. Hydatidiform mole typically presents in the first trimester with irregular vaginal bleeding and can be suspected on ultrasound but confirmation requires histopathological evaluation of the products of conception. Most molar pregnancies resolve without treatment after uterine evacuation, but occasionally the disease persists and develops into gestational trophoblastic neoplasia. Close monitoring of women after molar pregnancy, with regular measurement of human chorionic gonadotrophin concentrations, allows for early detection of malignancy. Given the rarity of the disease, clinical management and treatment is best provided in specialist centres where very high cure rates are achievable. This review looks at advances in the diagnosis and early management of gestational trophoblastic disease and highlights updates to disease classification and clinical guidelines. Use of molecular genotyping for improved diagnostic accuracy and risk stratification is reviewed and future biomarkers for the earlier detection of malignancy are considered.

Molar pregnancy in the last 50 years: A bibliometric analysis of global research output

Molar pregnancy is a gestational trophoblastic disease characterized by an abnormal growth of placental tissues because of a nonviable pregnancy. The understanding of the pathophysiology and management of molar pregnancy has significantly increased in the recent years. This study aims to determine the characteristics and trends of published articles in the field of molar pregnancy through a bibliometric analysis. Using the Scopus database, we identified all original research articles on molar pregnancy from 1970 to 2020. Bibliographic and citation information were obtained, and visualization of collaboration networks of countries and keywords related to molar pregnancy was conducted using VOSviewer software. We obtained a total of 2009 relevant papers published between 1970 and 2020 from 80 different countries. The number of publications continued to increase through the years. However, the number of publications in molar pregnancy is still low compared to the other research fields in obstetrics and gynecology. The USA (n = 421, 32.1%), Japan (n = 199, 15.2%), and the UK (n = 191, 14.6%) contributed the greatest number of publications in this field. The top journals which contributed to the field of molar pregnancy include AJOG (n = 91), Obstetrics and Gynecology (n = 81), and the Gynecologic Oncology (n = 57). The most cited articles in molar pregnancy include papers on the genetics and chromosomal abnormalities in molar pregnancies. The focus of current research in this field was on elucidating the molecular mechanism of hydatidiform moles. Our bibliometric analysis showed the global research landscape, trends and development, scientific impact, and collaboration among researchers in the field of molar pregnancy.

Genetics of gestational trophoblastic disease

The abnormal pregnancies complete and partial hydatidiform mole are genetically unusual, being associated with two copies of the paternal genome. Typical complete hydatidiform moles (CHMs) are diploid and androgenetic, while partial hydatidiform moles (PHMs) are diandric triploids. While diagnosis can usually be made on the basis of morphology, ancillary techniques that exploit their unusual genetic origin can be used to facilitate diagnosis. Genotyping and p57 immunostaining are now routinely used in the differential diagnosis of complete and partial hydatidiform moles, for investigating unusual mosaic or chimeric products of conception with a molar component and identifying the rare diploid, biparental HMs associated with an inherited predisposition to molar pregnancies. Genotyping also plays an important role in the differential diagnosis of gestational and non-gestational trophoblastic tumours and identification of the causative pregnancy where tumours are gestational. Recent developments include the use of cell-free DNA for non-invasive diagnosis of these conditions.

Gestational Trophoblastic Disease: Current Evaluation and Management

This review summarizes the current evaluation and management of gestational trophoblastic disease, including evacuation of hydatidiform moles, surveillance after evacuation of hydatidiform mole and the diagnosis and management of gestational trophoblastic neoplasia. Most women with gestational trophoblastic disease can be successfully managed with preservation of reproductive function. It is important to manage molar pregnancies properly to minimize acute complications and to identify gestational trophoblastic neoplasia promptly. Current International Federation of Gynecology and Obstetrics guidelines for making the diagnosis and staging of gestational trophoblastic neoplasia allow uniformity for reporting results of treatment. It is important to individualize treatment based on their risk factors, using less toxic therapy for patients with low-risk disease and aggressive multiagent therapy for patients with high-risk disease. Patients with gestational trophoblastic neoplasia should be managed in consultation with an individual experienced in the complex, multimodality treatment of these patients.

Recurrent GTD and GTD coexisting with normal twin pregnancy

Hydatidiform mole (HM) affects around 1/1000 pregnancies, and in such cases the recurrence risk is around 1%, being greater for those with complete HM (CHM). Whilst most cases appear sporadic with unknown mechanisms, there is a distinct subgroup of patients who suffer recurrent pregnancy loss, including multiple recurrent CHM (familial recurrent biparental HM syndrome). The majority of these cases are related to maternal genetic mutations in genes related to the control of imprinting, specifically NALP7 and KHDC3L. Oocyte donation is an effective treatment allowing these patients to have successful pregnancies. Approximately 1 in 50,000 pregnancies are complicated by twin pregnancy comprising normal foetus and HM, the majority of reported cases being CHM. Such pregnancies are at significantly increased risk of complications, including pregnancy loss, early-onset preeclampsia and severe preterm delivery, but when managed conservatively the delivery of a liveborn healthy infant occurs in around one-third of cases. Regardless of management, the risk of persistent GTD in such cases appears similar to that following singleton CHM. Rarely, other conditions mimic prenatal ultrasound appearances of twin pregnancy with HM, CHM mosaicism and placental mesenchymal dysplasia, both of which have distinctive histological and genetic features.

Which One Is More Prominent in Recurrent Hydatidiform Mole, Ovum or Sperm?

Recurrent hydatidiform mole is defined as episodes of two molar pregnancies in a female. Often, complete moles only derive androgenic nuclear genome. We described two cases with repeated molar pregnancies attempted to prevent future episodes by performing intracytoplasmic sperm injection (ICSI) and preimplantation genetic diagnosis (PGD) to assess genetic disorders. The first patient had previously six complete molar pregnancies and advised to carry out ICSI with ovum donation to achieve a normal pregnancy. The second case had previously five molar pregnancies and no XY embryos from the ICSI/PGD process. We had to (at the insistence of the patient) transfer XX embryos in this patient which resulted in a complete hydatidiform mole (CHM). Hence, available data based on our patients and previous studies demonstrated that oocyte might play a critical role in the pathophysiology of recurrent hydatidiform mole, while it has not been often considered.

NLRP7 and KHDC3L variants in Chinese patients with recurrent hydatidiform moles

OBJECTIVE

Recurrent hydatidiform moles are reportedly biparental complete moles and related to mutated NLRP7 and KHDC3L. This study was designed to identify mutations of gene NLRP7 and KHDC3L in biparental complete moles.

METHODS

In this study, we have screened NLRP7 and KHDC3L mutations in five patients with recurrent moles and five with sporadic moles. Molar tissues and blood samples were collected from patients and their partners. Genotypes of the molar tissues were determined based on short tandem repeat polymorphism. The coding exons of NLRP7 and KHDC3L were sequenced.

RESULTS

Two patients with recurrent moles had biparental complete moles, while all other patients had androgenetic complete moles. Three non-synonymous variants in NLRP7 (c.955 G>A, c.1280 T>C and c.1441 G>A) and one in KHDC3L (c.602 C>G) were identified in patients with recurrent moles. NLRP7 c.1441 G>A and c.1280 T>C were mutations found in the Chinese population, while c.1441 G>A was only detected in patients with biparental complete moles in this study.

CONCLUSIONS

Genotyping can be used to differentiate biparental complete moles from androgenetic moles and to predict the risk of recurrent moles in future pregnancies. NLRP7 c.1441 G>A may associate with biparental complete moles. Biparental complete moles exhibit genetic heterogeneity.

Molecular and Immunohistochemical Characteristics of Complete Hydatidiform Moles

Molar pregnancy is a gestational trophoblastic disease that belongs to the category of precancerous lesions. On the other end of the spectrum are gestational trophoblastic neoplasms such as invasive mole, choriocarcinoma, placental site trophoblastic tumor and epithelioid trophoblastic tumor, which are considered malignant tumors. Based on defined histopathological criteria, molar pregnancy is divided into partial and complete hydatidiform mole. Especially in the case of early complete mole, the diagnosis can be quite challenging and often necessitates additional molecular or immunohistochemical methods. The aim of this study was to assess the importance of additional molecular and immunohistochemical methods to accurately diagnose complete hydatidiform mole and to stress the importance of correct diagnosis and close follow-up of these patients. A total of 367 consecutive cases of spontaneous abortion were analyzed in a 3-year period. Eight cases with histopathological diagnosis of complete molar pregnancy were selected for further analysis. Apart from standard microscopic analysis, additional molecular and immunohistochemical analyses were performed in all eight cases. Most of the histopathological characteristics of complete molar pregnancy were present in all cases, together with complete absence of positivity for the p57 immunohistochemical marker in the cytotrophoblasts and villous stromal cells. The molecular analysis revealed androgenetic diploidy in seven cases and biparental diploidy in one case with more than three consecutive complete molar pregnancies. Additional immunohistochemical and molecular methods can considerably aid in the correct diagnosis of molar pregnancy.

Novel Nonsense Mutation in the NLRP7 Gene Associated with Recurrent Hydatidiform Mole

AIM

This study aimed to clarify the genetic and epigenetic features of recurrent hydatidiform mole (RHM) in Japanese patients.

METHODS

Four Japanese isolated RHM cases were analyzed using whole-exome sequencing. Villi from RHMs were collected by laser microdissection for genotyping and DNA methylation assay of differentially methylated regions (DMRs). Single nucleotide polymorphisms of PEG3 and H19 DMRs were used to confirm the parental origin of the variants.

RESULTS

A novel homozygous nonsense mutation in NLRP7 (c.584G>A; p.W195X) was identified in 1 patient. Genotyping of one of her molar tissue revealed that it was biparental but not androgenetic in origin. Despite the fact that the RHM is biparental, maternally methylated DMRs of PEG3, SNRPN and PEG10 showed complete loss of DNA methylation. A paternally methylated DMR of H19 retained normal methylation.

CONCLUSIONS

This is the first Japanese case of RHM with a novel homozygous nonsense NLRP7 mutation and a specific loss of maternal DNA methylation of DMRs. Notably, the mutation was identified in an isolated case of an ethnic background that has not previously been studied in this context. Our data underscore the involvement of NLRP7 in RHM pathophysiology and confirm that DNA methylation of specific regions is critical.

Discovery of a cell: reflections on the checkered history of intermediate trophoblast and update on its nature and pathologic manifestations

In 1976, a series of 12 cases describing a lesion that had previously not been well characterized was reported as "trophoblastic pseudotumor of the uterus." Up until that time rare reports of the lesion had classified it most often as an unusual type of sarcoma associated with pregnancy. All patients in that series were alive and well except for one who died from complications of a uterine perforation occurring at the time of a diagnostic curettage. Thus, it appeared to be a benign neoplasm but subsequently it was found that some exhibited malignant behavior and the tumor was renamed "placental site trophoblastic tumor." A variety of observations pointed to an origin in a distinctive cell of the placental site, designated "intermediate trophoblast," which physiologically is seen in the normal implantation site. Subsequently, another subset of intermediate trophoblast cells originating from the chorion laeve have been shown to give rise to the placental site nodule/plaque, a well-circumscribed and usually microscopic incidental finding as well as the epithelioid trophoblastic tumor, its putative malignant counterpart. The initial description of "trophoblastic pseudotumor" opened a new area of research which brought to bear immunohistochemical and molecular genetic analyses that eventually has led to new insights in the diverse morphologic changes occurring in early placentation and also led to the development of a new classification of trophoblastic tumors and tumor-like lesions.

Characteristics of hydatidiform moles: analysis of a prospective series with p57 immunohistochemistry and molecular genotyping

Immunohistochemical analysis of cyclin-dependent kinase inhibitor 1C (CDKN1C, p57, Kip2) expression and molecular genotyping accurately classify hydatidiform moles into complete and partial types and distinguish these from non-molar specimens. Characteristics of a prospective series of all potentially molar specimens encountered in a large gynecologic pathology practice are summarized. Initially, all specimens were subjected to both analyses; this was later modified to triage cases for genotyping based on p57 results: p57-negative cases diagnosed as complete hydatidiform moles without genotyping; all p57-positive cases genotyped. Of the 678 cases, 645 were definitively classified as complete hydatidiform mole (201), partial hydatidiform mole (158), non-molar (272), and androgenetic/biparental mosaic (14); 33 were unsatisfactory, complex, or problematic. Of the 201 complete hydatidiform moles, 104 were p57-negative androgenetic and an additional 95 were p57-negative (no genotyping), 1 was p57-positive (retained maternal chromosome 11) androgenetic, and 1 was p57-non-reactive androgenetic; 90 (85%) of the 106 genotyped complete hydatidiform moles were monospermic and 16 were dispermic. Of the 158 partial hydatidiform moles, 155 were diandric triploid, with 154 p57-positive, 1 p57-negative (loss of maternal chromosome 11), and 1 p57-non-reactive; 3 were triandric tetraploid, with 2 p57-positive and 1 p57-negative (loss of maternal chromosome 11). Of 155 diandric triploid partial hydatidiform moles, 153 (99%) were dispermic and 2 were monospermic. Of the 272 non-molar specimens, 259 were p57-positive biparental diploid, 5 were p57-positive digynic triploid, 2 were p57-negative biparental diploid (no morphological features of biparental hydatidiform mole), and 6 were p57-non-reactive biparental diploid. Of the 14 androgenetic/biparental mosaics with discordant p57 expression, 6 were uniformly mosaic and 8 had a p57-negative androgenetic molar component. p57 expression is highly correlated with genotyping, serves as a reliable marker for diagnosis of complete hydatidiform moles, and identifies androgenetic cell lines in mosaic conceptions. Cases with aberrant and discordant p57 expression can be correctly classified by genotyping.

Partial molar pregnancy after intracytoplasmic sperm injection occurring as a result of diploid sperm usage

PURPOSE

Partial molar pregnancies are rare conceptions characterized by having 69 rather than 46 chromosomes, the additional chromosome complement usually occurring as a result of fertilization of the ovum by two sperm. Although assisted conception with intracytoplasmic sperm injection (ICSI) should prevent the development of a partial molar pregnancy, occasional cases have been described after assisted conception using ICSI. The objective of this study was to investigate the cause of partial molar pregnancy in a couple who had undertaken assisted conception with ICSI.

METHODS

Fluorescent microsatellite genotyping of DNA from the couple and tissue from their partial molar pregnancy was performed in order to confirm diagnosis and investigate the origin of the additional chromosome set.

RESULTS

Genotyping confirmed that the partial molar tissue was triploid with an additional chromosome complement from the father. Genotyping of additional loci proximal to the centromere demonstrated that the two paternal sets of chromosomes originated in a single sperm with a double complement of paternal DNA resulting from non-reduction at the second meiotic division.

CONCLUSIONS

This study confirms that partial molar pregnancy may occur after assisted conception with ICSI and that this occurs as a result of fertilization with a diploid sperm.

Mutations in NLRP7 and KHDC3L confer a complete hydatidiform mole phenotype on digynic triploid conceptions

Digynic triploidy is classically associated with a severely growth restricted fetus and a small nonmolar placenta. However, in genotyping hydatidiform moles as part of clinical practice, we identified two digynic triploid conceptions presenting with histopathological features of classical complete hydatidiform mole (CHM). Both cases occurred in women with a history of previous molar pregnancies and no normal pregnancies. Pathological review and genotyping of other molar pregnancies in these cases showed them to be typical CHM with negative p57(KIP2) immunostaining of the cytotrophoblast cells and villous stroma and to be diploid but biparental, confirming a diagnosis of familial recurrent hydatidiform mole (FRHM). Mutation screening of NLRP7 had identified a homozygous duplication, leading to a truncated protein, in case 1 whereas mutation screening of KHDC3L (C6orf221) in case 2 showed both the proband and her sister to be compound heterozygotes for mutations in KHDC3L. The observation of a single digynic, triploid conception presenting as a CHM in women with FRHM, where other pregnancies are diploid and biparental, supports the hypothesis that the role of both NLRP7 and KHDC3L in pregnancy is in setting and/or maintaining the maternal imprint. Clinically, a diagnosis of FRHM should be considered in women with genetically unusual conceptions that are phenotypically CHM.

Recurrent hydatidiform mole: detection of two novel mutations in the NLRP7 gene in two Egyptian families

OBJECTIVES

Hydatidiform mole is an aberrant pregnancy with hyperproliferative vesicular trophoblast and defective fetal development. In 2006, mutations in NLRP7 were found to be responsible for recurrent hydatidiform moles (RHM), but genetic heterogeneity has been demonstrated and mutations of C6orf221 were later reported in several families. Here we report a new Egyptian family in which two sisters had eleven and four molar pregnancies, respectively. The objective was to present the results of the mutation analysis of NLRP7 and C6orf221 genes in Egyptian women with RHM.

STUDY DESIGN

Three women from two unrelated Egyptian families; two sisters and a previously described sporadic case, all presenting with RHM, were enrolled. The cases were subjected to detailed history taking, karyotyping and screening for mutations in NLRP7 and C6orf221.

RESULTS

Two NLRP7 mutations have been detected, one in each family. In the first family, sequencing identified a homozygous 2 bp deletion in the seventh coding exon of NLRP7, while a homozygous G-to-A substitution in the third coding exon of NLRP7 was detected in the second family. Both of them result in a truncated protein. The two mutations have not been previously described in the literature. No mutations in C6orf221 were found in any of the samples.

CONCLUSION

The detection of an NLRP7 mutation in both the familial and the apparently isolated case of RHM provides further evidence for the previously established role of NLRP7 mutations in the pathophysiology of RHM and increases the diversity of mutations described in the Egyptian population. Our results also expand further the spectrum of reproductive wastage associated with NLRP7 mutations to patients with recurrent spontaneous abortion.

Diagnostic reproducibility of hydatidiform moles: ancillary techniques (p57 immunohistochemistry and molecular genotyping) improve morphologic diagnosis

Distinction of hydatidiform moles (HMs) from nonmolar specimens (NMs) and subclassification of HMs as complete hydatidiform moles (CHMs) and partial hydatidiform moles (PHMs) are important for clinical practice and investigational studies; yet, diagnosis based solely on morphology is affected by interobserver variability. Molecular genotyping can distinguish these entities by discerning androgenetic diploidy, diandric triploidy, and biparental diploidy to diagnose CHMs, PHMs, and NMs, respectively. Eighty genotyped cases (27 CHMs, 27 PHMs, and 26 NMs) were selected from a series of 200 potentially molar specimens previously diagnosed using p57 immunostaining and genotyping. Cases were classified by 3 gynecologic pathologists on the basis of H&E slides (masked to p57 immunostaining and genotyping results) into 1 of 3 categories (CHM, PHM, or NM) during 2 diagnostic rounds; a third round incorporating p57 immunostaining results was also conducted. Consensus diagnoses (those rendered by 2 of 3 pathologists) were determined. Genotyping results were used as the gold standard for assessing diagnostic performance. Sensitivity of a diagnosis of CHM ranged from 59% to 100% for individual pathologists and from 70% to 81% by consensus; specificity ranged from 91% to 96% for individuals and from 94% to 98% by consensus. Sensitivity of a diagnosis of PHM ranged from 56% to 93% for individual pathologists and from 70% to 78% by consensus; specificity ranged from 58% to 92% for individuals and from 74% to 85% by consensus. The percentage of correct classification of all cases by morphology ranged from 55% to 75% for individual pathologists and from 70% to 75% by consensus. The κ values for interobserver agreement ranged from 0.59 to 0.73 (moderate to good) for a diagnosis of CHM, from 0.15 to 0.43 (poor to moderate) for PHM, and from 0.13 to 0.42 (poor to moderate) for NM. The κ values for intraobserver agreement ranged from 0.44 to 0.67 (moderate to good). Addition of the p57 immunostain improved sensitivity of a diagnosis of CHM to a range of 93% to 96% for individual pathologists and 96% by consensus; specificity was improved from a range of 96% to 98% for individual pathologists and 96% by consensus; there was no substantial impact on diagnosis of PHMs and NMs. Interobserver agreement for interpretation of the p57 immunostain was 0.96 (almost perfect). Even with morphologic assessment by gynecologic pathologists and p57 immunohistochemistry, 20% to 30% of cases will be misclassified, and, in particular, distinction of PHMs and NMs will remain problematic.

Molecular diagnosis of gestational trophoblastic disease

Gestational trophoblastic disease consists of well-defined diagnostic entities of proliferative disorder of the placenta, of which hydatidiform moles are common lesions. Even with available ancillary studies, including ploidy and immunohistochemistry analyses, histological diagnosis of molar pregnancies can be challenging in a significant percentage of the cases. Reliable diagnostic approaches with improved sensitivity and specificity are highly desirable. Recently, PCR-based short tandem repeat DNA genotyping has emerged as a powerful diagnostic measure in the workup of gestational trophoblastic disorders, particularly hydatidiform moles.

[Review: Repetitive hydatidiform moles]

Repetitive moles are rare. They are either sporadic or familial, with or without consanguinity. Some of them can be explained by a NLRP7 mutation, which causes genomic parental imprinting alteration, with a preferential paternal phenotypic expression. Currently, no effective therapeutic solution has been developed. Among the 1687 patients declared to the French Trophoblastic Disease Reference Center, 13 presented at least two hydatidiform moles, thus less than 1% of the patients. A mutation of the NLRP7 gene was shown in six of 12 tested patients (50%) among whom three presented a homozygous mutation and three a heterozygous mutation. For an affected patient, type of mole can indifferently be a complete hydatidiform mole or a partial hydatidiform mole. We describe these cases and compare them to those already published.

Histopathological diagnosis of hydatidiform mole: contemporary features and clinical implications

Gestational trophoblastic neoplasia (GTN) encompasses several entities including complete (CHM) and partial (PHM) hydatidiform mole (HM), malignant choriocarcinoma, and placental-site trophoblastic tumor. HMs are genetically abnormal, nonviable conceptions, which are associated with significantly increased risk for development of complications due to persistence of abnormal trophoblast (persistent GTN; pGTN), which occurs following 15% of CHM and 0.5% of PHM. Diagnostic histological features of HM are present in the first trimester but these features differ from those traditionally described in the later second trimester. The characteristic morphological findings of early HM include aspects of villous dysmorphism and abnormal villous trophoblast hyperplasia, with other specific features allowing reliable distinction between CHM and PHM. Optimal management of molar disease depends on its early histological identification and subsequent surveillance by measurement of maternal human chorionic gonoadotropin (hCG) for detection of pGTN based on rising or plateuing hCG levels such that early effective treatment is possible.

Differences in current clinical features of diploid and triploid hydatidiform mole

OBJECTIVE

To describe and compare the current clinical features of diploid and triploid molar pregnancy and to evaluate whether the presenting clinical features can predict the ploidy of a molar pregnancy.

DESIGN

A retrospective study of the clinical features and ploidy of hydatidiform moles.

SETTING

The Departments of Clinical Genetics and Pathology, Aarhus University Hospital and 13 gynaecological wards, Jutland, Denmark.

POPULATION

A total of 259 women with molar pregnancy diagnosed between April 1986 and June 2003.

METHODS

A review of medical records of consecutively collected, clinically suspected cases of molar pregnancy was performed. The molar ploidy was determined by karyotyping, flow cytometry, and/or analysis of polymorphic DNA markers.

MAIN OUTCOME MEASURES

Maternal characteristics, presenting symptoms, initial human chorionic gonadotrophin (hCG), and molar ploidy.

RESULTS

In a multiple logistic regression model, initial hCG of > or = 100,000 iu/l (P < 0.001), first-trimester gestational age (P < 0.001), vaginal bleeding (P < 0.001), and maternal age of > or = 40 years (P = 0.03) were independent predictors of diploid mole. Women with excessive uterine size more frequently had a diploid than a triploid mole (P < 0.001). Fifty-four percent of the women with triploid mole and 27% of the women with diploid mole were diagnosed before onset of symptoms (P < 0.001).

CONCLUSIONS

The current clinical features of diploid mole are different from those of triploid mole. The presenting clinical profile of a molar pregnancy may be used as an early predictor of the molar ploidy and thus of the prognosis.

Epigenetics in reproductive medicine

Imprinted genes comprise a small subset of the genome whose epigenetic reprogramming in the germ line is necessary for subsequent normal embryonic development. This reprogramming and resetting of the imprints, through an erasure/acquisition/maintenance cycle, is a subtle and tightly orchestrated phenomenon, involving specific genomic regions and methylation enzymes. Dysregulation of imprinted genes has indeed been shown to lead to several human disorders as well as to affect placental and fetal growth. There have been numerous and conflicting studies assessing the possible association of imprinting disorders with assisted reproductive techniques. This work analyzes all relevant and available reports with regard to the association between assisted reproductive techniques and imprinting disorders. It also discusses whether this possibly increased risk of imprinting disorders may be linked to specific steps of these reproductive techniques or already present in the gametes of infertile patients. A better understanding of epigenetic reprogramming in the germ line is absolutely necessary both to assess the safety of these methods and of the use of impaired spermatogenesis gametes for assisted reproduction.

Evaluation of deletions in 7q11.2 and 8p12–p21 as prognostic indicators of tumour development following molar pregnancy

OBJECTIVES

Previous studies have identified loss of chromosomal regions 7p12-q11.2 and 8p12-p21 in choriocarcinoma suggesting that suppressor genes involved in tumour development may be located within these regions. Our objectives were to refine the regions of loss and evaluate these deletions as prognostic indicators of trophoblastic tumour development following molar pregnancy.

METHODS

Fluorescent microsatellite genotyping was used to perform deletion mapping in a series of thirty-nine gestational trophoblastic tumours (GTT) including both choriocarcinoma and placental site trophoblastic tumours.

RESULTS

Significant loss of heterozygosity (LOH) was found for both regions in GTT that originated in non-molar pregnancies. Although no common interval of loss was found in those GTT with LOH for the 7q11.2 region, for the 8p12-p21 locus, markers D8S1731 and NEFL defined a minimal region of loss in all tumours showing LOH. However, complete LOH of either region occurred in only a minority of tumours (20%; chromosome 7: 24%; chromosome 8) suggesting that loss of neither region is likely to be a primary event in the development of GTT. This was further supported by the observation that no deletions were found in either region for the fourteen GTT that followed complete molar pregnancies.

CONCLUSIONS

While we have defined a minimal interval in 8p12-p21 in which tumour suppressor genes involved in GTT are likely to be located, the data suggest that deletions in 7q11.2 or 8p12-p21 are unlikely to be useful prognostic indicators in the management of patients with molar pregnancies.

Clinicopathologic characteristics and subsequent pregnancy outcome in 139 complete hydatidiform moles

OBJECTIVE

The most common form of gestational trophoblastic disease is the complete hydatidiform mole (CHM). The study reports our experience of clinicopathologic characteristics and subsequent pregnancy outcome of patients with CHM.

STUDY DESIGN

One hundred fifty-one subsequent cases with initial diagnosis of CHM were re-evaluated histopathologically. Clinical characteristics, the need for chemotherapy and subsequent pregnancy outcome were evaluated.

RESULTS

Twelve out of 151 cases were re-evaluated as hydropic abortion, as partial hydatidiform moles or were insufficient for morphologic examination and therefore excluded from further analysis. The leading clinical symptoms of the remaining 139 cases were irregular vaginal bleeding (67%) and uterine enlargement (41%). Twenty-six patients (19%) required chemotherapy because of gestational trophoblastic neoplasia (GTN; low-risk: 23 out of 26). All patients were cured successfully. The subsequent pregnancy rate was 15% (21/139). Five patients suffered from abortions, 12 women delivered a healthy offspring. Four women presented with recurrent CHM with a spontaneous normalization of HCG levels after D&C.

CONCLUSIONS

The clinical and morphologic diagnosis of CHM is a challenge, and diagnosis as well as treatment should be multidisciplinary and centralised. One fifth of CHM are at risk of a GTN, but the cure rate is 100% with adequate management. Pregnancy outcome following CHM is complicated by an increased risk of abortion.

Gestational trophoblastic disease following in vitro fertilization

BACKGROUND

Gestational trophoblastic disease (GTD) after fertility therapy seems to be a rare complication despite the widespread use of these treatments. Despite embryos derived from normally fertilized oocytes were transferred, molar pregnancies still occurring.

CASES

Two patients underwent first cycle of in vitro fertilization (IVF) for management of infertility related to tubal obstruction. GTD was diagnosed by histopathology.

CONCLUSION

It is unlikely that this complication is directly related to the technique of IVF itself but rather the characteristics of women and the partner attending for assisted conception make them more at risk of molar pregnancies. The management includes prompt curettage and regular follow-up.

Heterogeneity in the origin of recurrent complete hydatidiform moles: not all women with multiple molar pregnancies have biparental moles

Hydatidiform moles of two women, each with three molar pregnancies, were examined in order to study their origin. Multiple recurrences have previously been associated with women who have biparental complete hydatidiform moles (CHM). However, all the moles examined in this study were androgenetic CHM (AnCHM), indicating that recurrent (>2) moles, particularly in the absence of a positive family history, may be androgenetic rather than biparental. These data suggest that some women have a specific liability for having AnCHM. Making the distinction between a biparental or an androgenetic origin of recurrent moles is of relevance for counselling and when considering therapeutic options. Therefore, we propose that all recurrent moles should be investigated using molecular techniques.

Complete hydatidiform mole and normal live birth following intracytoplasmic sperm injection

A twin pregnancy with complete hydatidiform mole (HM) and preterm birth of a normal female infant after intracytoplasmic sperm injection (ICSI) conception was experienced. ICSI due to severe oligozoospermia was performed on three ova, and three embryos with confirmed two proneclei (2PN) were subsequently transferred to the uterus. At 7 weeks of gestation, molar pregnancy as well as a viable fetus was recognized. At 33 weeks, the pregnancy was terminated due to preterm labor. Dichorionic pregnancy consisting of a normal fetus and placenta in one chorionic membrane and complete HM in the other was recognized. Cytomolecular analysis indicated that the complete HM genome was derived from duplication of a single sperm, and a normal neonate was from biparental genomes. It should be noted that ICSI can avoid incomplete HM (mostly triploid) due to multi-sperm fertilization but might not be able to avoid complete HM (paternal diploid) although such a risk is very low. This is the second report of this condition and is accompanied by the first well-described molecular analysis.

Biparental hydatidiform moles: a maternal effect mutation affecting imprinting in the offspring

Highly recurrent hydatidiform moles (HMs) studied to date are not androgenetic but have biparental genomic contribution (BiHM). Affected women have an autosomal recessive mutation that causes their pregnancies to develop into HM. Although there is genetic heterogeneity, a major locus maps to chromosome 19q13.42, but a mutated gene has not yet been identified. Molecular studies have shown that maternal imprinting marks are deregulated in the BiHM trophoblast. The mutations that cause this condition are, therefore, hypothesized to occur in genes that encode transacting factors required for the establishment of imprinting marks in the maternal germline or for their maintenance in the embryo. Although only DNA methylation marks at imprinted loci have been studied in the BiHM, the mutation may affect genes that are essential for other forms of chromatin remodelling at imprinted loci and necessary for correct maternal allele-specific DNA methylation and imprinted gene expression. Normal pregnancies interspersed with BiHM have been reported in some of the pedigrees, but affected women repeatedly attempting pregnancy should be counselled about the risk for invasive trophoblastic disease with each subsequent BiHM.

Recurrent biparental hydatidiform mole: additional evidence for a 1.1-Mb locus in 19q13.4 and candidate gene analysis

OBJECTIVES

A maternal autosomal recessive mutation causing recurrent biparentally inherited complete hydatidiform moles (BiCHM) in affected women was previously mapped to a 12.4-cM interval in 19q13.4, which was recently further narrowed to a smaller 1.1-Mb region at the centromeric end. It is believed that the mutant gene in this condition is a major contributor to the regulation of imprinting in the maternal germline. To confirm and possibly narrow the critical interval we studied additional rare familial and recurrent cases.

METHODS

Using polymorphic marker analysis, we first confirmed biparental inheritance on the studied molar tissues. We then performed targeted homozygosity mapping with markers in 19q13.4 on DNA from affected women of a new large consanguineous pedigree, an additional potentially familial case, and three cases with sporadic recurrent CHM. Direct sequencing of coding exons and Southern analysis with a coding-region probe for one candidate gene (NALP5) was also performed.

RESULTS

Biparental inheritance was confirmed for those molar tissues available for analysis. All women, except for one of the isolated cases, were homozygous for markers in the identified 1.1-Mb region in 19q13.4. No mutations or large genomic rearrangements were found in NALP5 (MATER), a gene with oocyte-specific expression. Heterozygosity for a single-nucleotide polymorphism in exon 13 of NALP5 in one patient may refine the candidate region to 1.0 Mb.

CONCLUSIONS

The reported candidate region for BiCHM in 19q13.4 was confirmed in additional families, further establishing it as the major locus that harbors a gene mutated in this condition.

Familial hydatidiform molar pregnancy: the germline imprinting defect hypothesis?

Imprinting is the uniparental expression of a set of genes. Somatic cells carry two haploid sets of chromosomes, one maternal and one paternal, while germ cells contain only one of the two forms of chromosomes, male or female. This implies that during early embryogenesis the cells committed for developing the future germ cell lineage, the primordial germ cells, which are diploid, have to undergo a total chromosome reprogramming process. This process is delicately controlled during gametogenesis to ensure that males and females have only their respective form of gametes. The machinery involved in this process is yet poorly defined. Familial hydatidiform molar (HM) pregnancy is an abnormal form of pregnancy characterized by hydropic degeneration of placental villi and abnormal, or absence of, embryonic development. To date, the molecular defect causing this condition is unknown. However, in a few studied cases, the presence of paternal methylation patterns on the maternal chromosomes was observed. In this chapter, we summarize what is known about methylation aberrations in HMs and examine more closely the proposed hypothesis of a maternal germline imprinting defect.

Analysis of the chromosomal region 19q13.4 in two Chinese families with recurrent hydatidiform mole

BACKGROUND

Familial recurrent hydatidiform mole is an extremely rare autosomal recessive condition in which affected individuals have a predisposition to molar pregnancies that are diploid but biparental, rather than androgenetic, in origin. A gene for this condition has been previously mapped to a 1.1 Mb region of chromosome 19q13.4. However, investigation of further families is needed to refine the location of the specific gene(s) involved.

METHODS

We have recently identified two novel Chinese families in which four affected women had recurrent pregnancy loss including 14 complete hydatidiform moles (CHM). Fluorescent microsatellite genotyping was used to determine the origin of CHM in both families. Using a panel of polymorphic microsatellite markers, genotyping and haplotype analysis of the 19q13.4 chromosomal region was performed in both families.

RESULTS

Genotyping of CHM from affected individuals confirmed their biparental origin and diagnosis of familial recurrent hydatidiform mole in both families. However, no significant homozygosity for the 19q13.4 candidate region was found in affected members of either family.

CONCLUSION

Genotyping and haplotype analysis has shown that a mutation in 19q13.4 is unlikely to be responsible for recurrent CHM in the two Chinese families investigated and provides further evidence to support the hypothesis that, although extremely rare, this condition shows genetic heterogeneity.