Androgenetic Complete Hydatidiform Mole Research Articles

Evaluation of Combined p57KIP2 Immunohistochemistry and Fluorescent in situ Hybridization Analysis for Hydatidiform Moles Compared with Genotyping Diagnosis.

Immunostaining with p57KIP2 is a widely used diagnostic technique to differentiate complete hydatidiform moles (CHMs) from partial hydatidiform moles (PHM) and non-molar hydropic abortion. However, distinguishing between PHMs and non-molar hydropic abortions using histopathology alone is often challenging. This study aimed to evaluate the technical validity and additional benefits of using fluorescence in situ hybridization (FISH) in combination with p57KIP2 immunostaining to diagnose molar and non-molar conceptuses. The study involved 80 specimens, which underwent genetic diagnosis using short tandem repeat analysis, including 44 androgenetic CHMs, 20 diandric monogynic PHMs, 14 biparental non-molar hydropic abortions, 1 monoandric digynic triploid abortion, and 1 vaginal specimen of gestational trophoblastic neoplasia. Two pathologists independently diagnosed the cases based on morphology and p57KIP2 immunostaining while the clinical information was masked. FISH analysis was performed using 3 probes (CEP17, CEPX, and CEPY), which revealed that all androgenetic CHM and biparental diploid non-molar hydropic abortion specimens were diploid. Among the 20 diandric monogynic PHM cases examined by analyzing short tandem repeat polymorphisms, 18 were triploid, and the remaining 2 were diploid. These two specimens were possibly androgenetic/biparental mosaics based on FISH analysis, where the three-signal ratios counting 50 cells were clearly within the diploid ranges. Eight of the 20 genetic PHMs and 2 of the 14 genetically confirmed non-molar hydropic abortions that were falsely diagnosed based on morphology and immunohistochemistry by at least 1 pathologist were correctly diagnosed as PHM and non-molar hydropic abortion, respectively, by FISH analysis. However, 1 monoandric digynic villus was classified as triploid by FISH analysis, leading to a false PHM diagnosis. In conclusion, the combination of FISH analysis with p57KIP2 immunostaining helps in diagnosing molar and non-molar conceptuses in numerous cases; nevertheless, exceptional cases should be considered.

"While there is p57, there is hope." The past and the present of diagnosis in first trimester abortions: Diagnostic dilemmas and algorithmic approaches. A review.

Distinction of hydatidiform moles (HM) from non-molar (NM) specimens and subclassification of HM as complete hydatidiform mole (CHM) versus partial hydatidiform mole (PHM) are important for clinical practice and investigational studies. The issue of diagnostic reproducibility is still unsolved, the lack of diagnostic accuracy based on morphology is substantial with an important interobserver variability, even between experienced gynecologic pathologists. Many ancillary techniques have been investigated in the last years to refine HM diagnosis. p57 (a paternally imprinted, maternally expressed gene) immunohistochemistry, based on the unique genetics of CHM (purely androgenetic), PHM (diandric triploid), and NM specimens (biparental, with allelic balance) can identify CHMs, which lack p57 expression because of a lack of maternal DNA. However, although its role in HM diagnosis is pivotal, it does not allow the distinction of PHM from NM specimens, both of which express p57 due to the presence of maternal DNA. Molecular genotyping, which compares villous and decidual DNA patterns to determine the parental source and ratios of polymorphic alleles, distinguishes purely androgenetic CHM from diandric triploid PHM, and both of these from NM specimens. Beyond the claim of establishing a "diagnostic truth", exceptions and peculiar genetic scenarios in the origin of rare CHM and PHM should be kept in mind when approaching any ancillary technique. An algorithmic approach, even in settings with limited resources, can help the pathologists in the diagnostic dilemma of diagnosis of first trimester abortions.

Parental contribution to trisomy in heterozygous androgenetic complete moles

Complete hydatidiform moles (CHMs) comprise a proliferative trophoblastic disorder and are known to be androgenetic and diploid. Androgenetic CHMs are classified as having monospermic and dispermic origins. Rarely, some CHMs have other genetic constitutions, such as biparental diploid or tetraploid. Previous studies have shown the possibility that androgenetic heterozygous CHMs have an additional chromosome with high frequency. This study aimed to comprehensively analyse the molecular karyotyping of androgenetic dispermic CHMs and the parental contribution of their additional chromosomes. Single-nucleotide polymorphism arrays were performed with the genomic DNA of CHMs and patients. The B allele frequency and selected B allele frequency plotting of CHM were visualised. Among the 31 dispermic CHMs, eight showed trisomy and one showed double trisomy; of the 10 additional chromosomes, seven were of maternal original and three were of paternal origin. In addition, three disomic chromosomes comprised one maternal and one paternal chromosome, although these should theoretically have had two paternal chromosomes in the case of androgenetic CHMs. The subclassification of heterozygous CHMs, with or without maternal contribution, is a new approach and could be a candidate indicator of gestational trophoblastic neoplasia risk.

Loss of X Chromosome Inactivation in Androgenetic Complete Hydatidiform Moles With 46, XX Karyotype.

Most complete hydatidiform moles (CHMs) showcase an androgenetic nature of the nuclear genome. In the normal female embryo, one of the 2 X chromosomes is inactive. However, the status of X chromosome inactivation (XCI) in androgenetic CHMs remains unknown. Seventy-one androgenetic CHM tissues with the 46, XX karyotype were collected. Seventy-four normal female villi and 74 normal male villi were collected as controls. The expression of XCI markers (XIST, TSIX, and XACT) and an X-linked gene (CDX4) was detected by real-time polymerase chain reaction. Other XCI-associated genes were also examined, including the methylation status of the human androgen receptor gene (HUMARA) by methylation-specific polymerase chain reaction), and the expression of H3K27me3, USP21, and Nanog by Western blot and immunofluorescence, respectively. In addition, 126 CHMs and 63 normal female villous samples were collected for CDX4 immunohistochemical staining. The expression of XIST RNA was significantly lower, and TSIX RNA expression was significantly higher in androgenetic CHMs than that in normal female villi (both P<0.01). The expression of CDX4 mRNA in androgenetic CHMs was elevated compared with that in normal male and normal female villous samples (both P<0.01), and CDX4 protein expression was also higher than that in normal female villous samples (P<0.01). The expression of H3K27me3 was lower in androgenetic CHMs compared with that in normal female villi(P<0.01). The methylation pattern of HUMARA was found lacking in androgenetic CHMs. The expression of Nanog and UPS21 protein in androgenetic CHMs was higher than that in normal villi (both P<0.01). Both X chromosomes are active in androgenetic CHMs with the 46, XX karyotype, and the USP21-Nanog pathway may be involved in the disruption of XCI during this process.

ABO blood type compatibility is not a risk factor for gestationaltrophoblastic neoplasia development from androgenetic completehydatidiform moles.

Complete hydatidiform moles (CHMs) are allografts to patients in terms of an androgenetic origin. Thus, some immunological reactions may be involved in the development of gestational trophoblastic neoplasia (GTN) from CHMs. This study aimed to evaluate the effect of ABO blood group on the prognosis of androgenetic CHMs. A total of 129 patients who were diagnosed as having CHMs based on multiplex short tandem repeat polymorphism analysis were included. The ABO blood types of molar tissues were determined by single-nucleotide polymorphisms in the ABO gene using a high-resolution melting assay. The incidence of GTN was compared based on ABO compatibility between the patients and their molar tissues. The overall incidence of GTN was 17.1% (22/129). Gestational trophoblastic neoplasia occurred in 10.8% (4/37), 14.8% (8/54), 22.2% (6/27), and 36.4% (4/11) of type O, A, B, and AB patients, respectively. Type AB patients tended to develop GTN compared with other blood type patients (P=.093). In ABO type of CHMs, GTN occurrence was not significantly different as it was 16.4% (10/64), 16.0% (8/50), and 22.2% (4/18) for types O, A, and B, respectively (P=.854). According to the ABO incompatibility between patients and molar tissues, GTN occurred in 19.1% (18/94) of the compatible cases and 11.4% (4/35) of the incompatible cases; the occurrence was not significantly different (P=.223). Patients with type AB tended to develop GTN. However, ABO compatibility between patients and molar tissues had no relationship with GTN occurrence.

Generation of human androgenetic induced pluripotent stem cells

In humans, parthenogenesis and androgenesis occur naturally in mature cystic ovarian teratomas and androgenetic complete hydatidiform moles (CHM), respectively. Our previous study has reported human parthenogenetic induced pluripotent stem cells from ovarian teratoma–derived fibroblasts and screening of imprinted genes using genome-wide DNA methylation analysis. However, due to the lack of the counterparts of uniparental cells, identification of new imprinted differentially methylated regions has been limited. CHM are inherited from only the paternal genome. In this study, we generated human androgenetic induced pluripotent stem cells (AgHiPSCs) from primary androgenetic fibroblasts derived from CHM. To investigate the pluripotency state of AgHiPSCs, we analyzed their cellular and molecular characteristics. We tested the DNA methylation status of imprinted genes using bisulfite sequencing and demonstrated the androgenetic identity of AgHiPSCs. AgHiPSCs might be an attractive alternative source of human androgenetic embryonic stem cells. Furthermore, AgHiPSCs can be used in regenerative medicine, for analysis of genomic imprinting, to study imprinting-related development, and for disease modeling in humans.

Comparison between vacuum aspiration and forceps plus blunt curettage for the evacuation of complete hydatidiform moles

ObjectiveSuction curettage is recommended for molar evacuation rather than sharp curettage because of its safety. However, the superiority of suction curettage with respect to the incidence of gestational trophoblastic neoplasia (GTN) has not been reported. This study aimed to compare the efficacy and safety of two evacuation procedures, vacuum aspiration and forceps/blunt curettage, for complete hydatidiform moles (CHMs) to determine the differences between them. Materials and methodsPatients with androgenetic CHM determined by multiplex short tandem repeat polymorphism analysis were included in this observational cohort study. Patients underwent evacuation with forceps and blunt curettage (forceps group) before March 2013 and with vacuum aspiration (vacuum group) thereafter. GTN was diagnosed based on the International Federation of Gynecology and Obstetrics 2000 criteria. The incidence of GTN and other clinical parameters were compared. ResultsNinety-two patients were diagnosed with androgenetic CHM. The number of patients in the forceps and vacuum groups was 41 and 51, respectively. The incidence of GTN was 12.2% (5/41) and 13.7% (7/51) in the forceps and vacuum groups, respectively, which was not significantly different (P = 1, Fisher's exact test). No major adverse events, such as uterine perforation and blood transfusion, were noted in either group. The median surgery time was shorter in the vacuum group (16 min) than in the forceps group (25 min) (P = 0.05, Mann–Whitney U test). ConclusionThere were no differences in the incidence of GTN between the forceps and vacuum groups for androgenetic CHM. However, vacuum aspiration could have the advantage of a shorter surgery period. The use of vacuum aspiration for molar pregnancy seems to be safer. Therefore, we recommend suction curettage for the first evacuation of hydatidiform moles.

Hydatidiform Moles: Ancillary Techniques to Refine Diagnosis.

Distinction of hydatidiform moles from nonmolar specimens and subclassification of hydatidiform moles as complete hydatidiform mole versus partial hydatidiform mole are important for clinical practice and investigational studies. Risk of persistent gestational trophoblastic disease and clinical management differ for these entities. Diagnosis based on morphology is subject to interobserver variability and remains problematic, even for experienced gynecologic pathologists. To explain how ancillary techniques target the unique genetic features of hydatidiform moles to establish diagnostic truth, highlight the issue of diagnostic reproducibility and importance of diagnostic accuracy, and illustrate use of p57 immunohistochemistry and polymerase chain reaction-based DNA genotyping for diagnosis. Sources are the author's 10-year experience using ancillary techniques for the evaluation of potentially molar specimens in a large gynecologic pathology practice and the literature. The unique genetics of complete hydatidiform moles (purely androgenetic), partial hydatidiform moles (diandric triploid), and nonmolar specimens (biparental, with allelic balance) allow for certain techniques, including immunohistochemical analysis of p57 expression (a paternally imprinted, maternally expressed gene) and genotyping, to refine diagnoses of hydatidiform moles. Although p57 immunostaining alone can identify complete hydatidiform moles, which lack p57 expression because of a lack of maternal DNA, this analysis does not distinguish partial hydatidiform moles from nonmolar specimens because both express p57 because of the presence of maternal DNA. Genotyping, which compares villous and decidual DNA patterns to determine the parental source and ratios of polymorphic alleles, distinguishes purely androgenetic complete hydatidiform moles from diandric triploid partial hydatidiform moles, and both of these from biparental nonmolar specimens. An algorithmic approach to diagnosis using these techniques is advocated.

Causative Mutations and Mechanism of Androgenetic Hydatidiform Moles

Androgenetic complete hydatidiform moles are human pregnancies with no embryos and affect 1 in every 1,400 pregnancies. They have mostly androgenetic monospermic genomes with all the chromosomes originating from a haploid sperm and no maternal chromosomes. Androgenetic complete hydatidiform moles were described in 1977, but how they occur has remained an open question. We identified bi-allelic deleterious mutations in MEI1, TOP6BL/C11orf80, and REC114, with roles in meiotic double-strand breaks formation in women with recurrent androgenetic complete hydatidiform moles. We investigated the occurrence of androgenesis in Mei1-deficient female mice and discovered that 8% of their oocytes lose all their chromosomes by extruding them with the spindles into the first polar body. We demonstrate that Mei1-/- oocytes are capable of fertilization and 5% produce androgenetic zygotes. Thus, we uncover a meiotic abnormality in mammals and a mechanism for the genesis of androgenetic zygotes that is the extrusion of all maternal chromosomes and their spindles into the first polar body.

Gestational Trophoblastic Neoplasia From Genetically Confirmed Hydatidiform Moles: Prospective Observational Cohort Study.

The aim of this study was to evaluate the incidence and risk factors of gestational trophoblastic neoplasia (GTN) from hydatidiform moles (HMs) cytogenetically diagnosed in a prospective cohort setting. The prospective observational cohort study included cases of cytogenetically defined molar pregnancies, which were diagnosed by a multiplex short tandem repeat polymorphism analysis. Cases were classified as androgenetic complete HMs (CHMs), diandric monogynic triploid partial HMs (PHMs), or biparental abortion. Gestational trophoblastic neoplasia was diagnosed according to the International Federation of Gynecology and Obstetrics 2000 criteria. Incidences for each category, that is, CHM, PHMs, and biparental abortion, were calculated. Clinical variables (age, partner age, gravidity, parity, height, weight, BMI, and gestational age) and laboratory data (serum human chorionic gonadotropin [hCG], white blood cell count, hemoglobin, and platelet count) were compared between spontaneous remission cases and GTN cases in androgenetic CHMs. Among 401 cases, 380 were classified as follows: 232 androgenetic CHMs, 60 diandric monogynic PHMs, and 88 biparental abortions. A total of 35 cases (15.1%) of CHMs, but only 1 case of PHM (1.7%) and no biparental abortions, exhibited progression to GTN. The hCG value before evacuation was significantly higher in GTN cases than in spontaneous remission cases (P = 0.001, Kruskal-Wallis test). Patient age was also significantly higher in GTN cases than in spontaneous remission cases (P = 0.002, Student t test). Under the cohort cytogenetic diagnosis setting, the traditional risk factors for GTN after molar pregnancy, hCG value before evacuation and age, were confirmed in androgenetic CHMs. The risk of GTN was lower for PHMs than for CHMs. However, 1 patient with cytogenetic PHMs developed into GTN.

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.

Regulation of expression of p57KIP2 gene in extravillous trophoblast cells

Regulation of expression of p57KIP2 gene in extravillous trophoblast cells

No evidence for mutations in NLRP7 and KHDC3L in women with androgenetic hydatidiform moles

The objective of this study was to evaluate the mutational spectrum of NLRP7 and KHDC3L (C6orf221) in women with sporadic and recurrent androgenetic complete hydatidiform moles (AnCHM) and biparental hydatidiform moles (BiHM) to address the hypothesis that autosomal recessive mutations in these genes are only or primarily associated with BiHM. We recruited 16 women with suspected recurrent and sporadic AnCHM and five women with suspected BiHM in addition to their reproductive partners into our study. We then sequenced the coding exons of NLRP7 and KHDC3L from DNA isolated from either blood or saliva from the study subjects. Sequence analysis of NLRP7 and KHDC3L revealed previously described single nucleotide polymorphisms in patients with AnCHM. However, in patients with BiHM, we identified a novel homozygous mutation and a previously described intragenic duplication of exons 2 to 5 in NLRP7, both of which are likely to be disease causing. We did not identify mutations in KHDC3L in patients with either form of hydatidiform moles. The absence of mutations in women with AnCHM supports a role for NLRP7 or KHDC3L in BiHM only. The absence of mutations in KHDC3L in women with BiHM is consistent with its minor role in this disease compared with NLRP7, the major BiHM gene.

Characterization of Androgenetic/Biparental Mosaic/Chimeric Conceptions, Including Those With a Molar Component

Recent studies have demonstrated the value of ancillary techniques, including p57 immunohistochemistry and short tandem repeat genotyping, for distinguishing hydatidiform moles (HM) from nonmolar specimens and for subtyping HMs as complete hydatidiform moles (CHM) and partial hydatidiform moles (PHM). With rare exceptions, CHMs are p57-negative and androgenetic diploid; partial hydatidiform moles are p57-positive and diandric triploid; and nonmolar specimens are p57-positive and biparental diploid. Androgenetic/biparental mosaic/chimeric conceptions can have morphologic features that overlap with HMs but are genetically distinct. This study characterizes 11 androgenetic/biparental mosaic/chimeric conceptions identified in a series of 473 products of conception specimens subjected to p57 immunohistochemistry and short tandem repeat genotyping. Fluorescence in situ hybridization was performed on 10 to assess ploidy. All cases were characterized by hydropically enlarged, variably sized and shaped villi. In 5 cases, the villi lacked trophoblastic hyperplasia, whereas in 6 there was a focal to extensive villous component with trophoblastic hyperplasia and features of CHM. The villi lacking trophoblastic hyperplasia were characterized by discordant p57 expression within individual villi (p57-positive cytotrophoblast and p57-negative stromal cells), whereas the villous components having trophoblastic hyperplasia were uniformly p57-negative in both cell types. Short tandem repeat genotyping of at least 2 villous areas in each case demonstrated an excess of paternal alleles in all regions, with variable paternal:maternal allele ratios (usually >2:1); pure androgenetic diploidy was identified in those cases with a sufficiently sized villous component having trophoblastic hyperplasia and features of CHM. Fluorescence in situ hybridization demonstrated uniform diploidy in 7 cases, including 4 of 5 tested cases with trophoblastic hyperplasia and 3 of 5 cases without trophoblastic hyperplasia. Two cases without trophoblastic hyperplasia had uniformly diploid villous stromal cells but 1 had triploid and 1 had tetraploid cytotrophoblast; 1 case with trophoblastic hyperplasia had uniformly diploid villous stromal cells but a mixture of diploid, triploid, and tetraploid cytotrophoblast. In 3 cases with a CHM component, persistent gestational trophoblastic disease developed. These results indicate that androgenetic/biparental mosaic/chimeric conceptions are most often an admixture of androgenetic diploid (p57-negative) and biparental diploid (p57-positive) cell lines but some have localized hyperdiploid components. Recognition of their distinctive p57 expression patterns and genotyping results can prevent misclassification as typical CHMs, PHMs, or nonmolar specimens. The presence of androgenetic cell lines, particularly in those with a purely androgenetic CHM component, warrants follow-up because of some risk of persistent gestational trophoblastic disease.

A novel approach identifies new differentially methylated regions (DMRs) associated with imprinted genes

Imprinted genes are critical for normal human growth and neurodevelopment. They are characterized by differentially methylated regions (DMRs) of DNA that confer parent of origin-specific transcription. We developed a new strategy to identify imprinted gene-associated DMRs. Using genome-wide methylation profiling of sodium bisulfite modified DNA from normal human tissues of biparental origin, candidate DMRs were identified by selecting CpGs with methylation levels consistent with putative allelic differential methylation. In parallel, the methylation profiles of tissues of uniparental origin, i.e., paternally-derived androgenetic complete hydatidiform moles (AnCHMs), and maternally-derived mature cystic ovarian teratoma (MCT), were examined and then used to identify CpGs with parent of origin-specific DNA methylation. With this approach, we found known DMRs associated with imprinted genomic regions as well as new DMRs for known imprinted genes, NAP1L5 and ZNF597, and novel candidate imprinted genes. The paternally methylated DMR for one candidate, AXL, a receptor tyrosine kinase, was also validated in experiments with mouse embryos that demonstrated Axl was expressed preferentially from the maternal allele in a DNA methylation-dependent manner.

Genetic genesis of choriocarcinoma

To distinguish choriocarcinoma from gestational or non-gestational choriocarcinoma and also identify the causative pregnancy of gestational choriocarcinoma by the genetic origin through molecular genetic analysis. Twelve patients with choriocarcinoma, who had experienced surgery prior to chemotherapy were enrolled in this study. All 12 cases were diagnosed pathologically as choriocarcinoma. Peripheral venous blood samples and formalin-fixed paraffin-embedded blocks of choriocarcinoma tissue microdissected from haematoxylin and eosin-stained sections of tissue by microdissection method were available from the patient and (or) her husband. DNA was then prepared from the couples' blood samples and choriocarcinoma tissue by using standard techniques. PCR amplification and fluorescent microsatellite genotyping were performed by using DNA from the couples and captured choriocarcinoma tissues. The genetic contributions to the choriocarcinoma tissue were determined by comparing the fragments of genes from the choriocarcinoma tissue to those from blood samples of the couples. The primary lesion was ovary in 7 cases, but only 4 of them had the maternal contribution, indicating a non-gestational origin; the other three were gestational choriocarcinoma. The primary lesion was uterus in 5 cases, which were all gestational choriocarcinoma confirmed by genetic analyses. The causative pregnancies of the 8 cases with gestational choriocarcinoma were identified as androgenetic complete hydatidiform mole (AnCHM) in six cases and normal pregnancies in two cases, respectively. Microsatellite polymorphism analysis is a molecular approach for distinguishing the non-gestational choriocarcinoma from the gestational one, and also be used to identify the causative pregnancy of gestational choriocarcinoma.

Molecular Genetic Analyses of Choriocarcinoma

Background Choriocarcinoma is a highly malignant trophoblastic neoplasm. Most of them are gestational in origin, while non-gestational ones are exceedingly rare. The genetic origin, immunogenicity, sensitivity to chemotherapy and prognosis of these two kinds of conditions are quite different, so identification of these two kinds of choriocarcinoma is of great importance. The objective of this study is to distinguish choriocarcinoma as gestational or non-gestational and identify the causative pregnancy of gestational choriocarcinoma through molecular genetic analysis. Methods Twelve patients with choriocarcinoma, who had experienced surgery prior to chemotherapy, were enrolled in this study. DNA was prepared from blood samples from the patient and her partner using standard techniques. In order to prepare DNA from choriocarcinoma tissue, areas of choriocarcinoma were firstly microdissected from haematoxylin and eosin-stained sections. PCR amplification and fluorescent microsatellite genotyping were performed using DNA from the couples and captured tissue. The genetic contributions to the choriocarcinoma were determined by comparing the genotypes of the choriocarcinoma and that of the couples. Results Four of twelve cases had only a maternal contribution, indicating a non-gestational origin. The remaining eight cases were all gestational in origin and the causative pregnancies were identified as AnCHM (androgenetic complete hydatidiform mole) in six and normal pregnancies in two respectively. Conclusion Microsatellite polymorphism analysis is a molecular approach for distinguishing the non-gestational choriocarcinoma from the gestational one, and can also be used to identify the causative pregnancy of gestational choriocarcinoma. Antecedent pregnancy prior to choriocarcinoma is not always its causative pregnancy. Therefore, it is reasonable to identify the causative pregnancy by its genetic origin, instead of clinical impression.

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.

Immunohistochemical characterization of p57Kip2 expression in tetraploid hydropic placentas.

Because there are differences in the origin, morphology, and natural history of hydropic placental villous issues, it is important to identify and document rare specimens that deviate from the diploid complete hydatidiform mole (CM), triploid partial hydatidiform mole (PM), or diploid hydropic abortion (HA). Tetraploid hydropic placentas have rarely been studied. To evaluate the frequency of p57Kip2 protein (p57) expression in tetraploid hydropic placentas and to determine its clinicopathologic significance. Forty hydropic DNA tetraploid placental specimens were evaluated by immunohistochemistry of formalin-fixed tissues, using a monoclonal antibody against p57, a putative paternally imprinted inhibitor gene. DNA ploidy in all cases was analyzed by flow cytometry. Thirty cases were histologically diagnosed as CMs, 10 were HAs, and none were PMs. In all HAs, nuclear p57 was strongly expressed in cytotrophoblasts, intermediate trophoblasts, and villous stromal cells. In contrast, in CMs, p57 expression in cytotrophoblasts and villous stromal cells was either absent (26 cases) or very low (4 cases). Assuming that the degree of molar change roughly correlates with the proportion of paternal chromosomes present, all chromosomes might be paternally derived in all tetraploid CMs and the 10 HAs, including 2 that were karyotyped as 92,XXYY or 90,XXYY,-13,-14, which were presumably due to 2 sets of chromosomes each from paternal and maternal origin. Expression of p57 is aberrant in tetraploid CMs. This finding is in line with the hypothesis that the loss of p57 is involved in the abnormal development of androgenetic CMs. For the evaluation of a patient with trophoblastic disease, p57 immunostaining is an ancillary diagnostic method that may be used in concert with flow cytometry.

The Product of the Imprinted Gene IPL Marks Human Villous Cytotrophoblast and is Lost in Complete Hydatidiform Mole

The IPL/TSSC3 gene is expressed nearly exclusively from the maternal allele, and its protein product acts to limit placental growth in mice. This protein specifically marks Type II trophoblast in the labyrinthine layer of the mouse placenta. To investigate mouse–human homologies, we carried out immunohistochemistry with antibodies against human IPL. There was strong expression of IPL in villous cytotrophoblast of the human placenta, contrasting with complete lack of expression in syncytiotrophoblast. Staining for IPL was weak in cells of the villous mesenchyme and extravillous trophoblast, including the cytotrophoblast columns in the basal plate and the intervillous trophoblast islands. The IPL and p57 KIP2 /CDKN1C genes are closely linked and coordinately imprinted, and immunostaining showed that their protein products are co-expressed in villous cytotrophoblast. However, other cell types, including extravillous cytotrophoblast and cells in various non-placental tissues, expressed p57 KIP2, but not IPL. IPL protein was absent in both of two cases of androgenetic complete hydatidiform mole examined by immunostaining, and IPL mRNA was absent in an additional three cases of this neoplasm examined by northern blotting. In the mouse, Ipl-expressing cells disappear at mid- to late-gestation when placental growth ceases, but persistent IPL mRNA and protein expression was observed throughout human gestation, correlating with the continuous growth of the human placenta. These findings highlight dosage regulation of human IPL by imprinting and, more generally, suggest homology between Type II labyrinthine trophoblast in the mouse and villous cytotrophoblast in humans, both of which are proliferative stem cell-like compartments.