HLA-C expression in extravillous trophoblasts is determined by an ELF3-NLRP2/NLRP7 regulatory axis.

The distinct human leukocyte antigen (HLA) class I expression pattern of human extravillous trophoblasts (EVT) endows them with unique tolerogenic properties that enable successful pregnancy. Nevertheless, how this process is elaborately regulated remains elusive. Previously, E74 like ETS transcription factor 3 (ELF3) was identified to govern high-level HLA-C expression in EVT. In the present study, ELF3 is found to bind to the enhancer region of two adjacent NOD-like receptor (NLR) genes, NLR family pyrin domain-containing 2 and 7 (NLRP2, NLRP7). Notably, our analysis of ELF3-deficient JEG-3 cells, a human choriocarcinoma cell line widely used to study EVT biology, suggests that ELF3 transactivates NLRP7 while suppressing the expression of NLRP2. Moreover, we find that NLRP2 and NLRP7 have opposing effects on HLA-C expression, thus implicating them in immune evasion at the maternal-fetal interface. We confirmed that NLRP2 suppresses HLA-C levels and described a unique role for NLRP7 in promoting HLA-C expression in JEG-3. These results suggest that these two NLR genes, which arose via gene duplication in primates, are fine-tuned by ELF3 yet have acquired divergent functions to enable proper expression levels of HLA-C in EVT, presumably through modulating the degradation kinetics of IkBα. Targeting the ELF3-NLRP2/NLRP7-HLA-C axis may hold therapeutic potential for managing pregnancy-related disorders, such as recurrent hydatidiform moles and fetal growth restriction, and thus improve placental development and pregnancy outcomes.

High Risk of Gestational Trophoblastic Neoplasia Development in Recurrent Hydatidiform Moles with NLRP7 Pathogenic Variations.

Objective: Pathogenic variations of the NLRP7 and KHDC3L genes are responsible for familial recurrent hydatidiform moles, a rare autosomal recessive phenomenon that can lead to severe comorbidities. Little is known about the diversity of genetic defects or the natural course of disease progression among recurrent hydatidiform mole cases from distinct ethnicities. In this study, we aimed to investigate the mutation profile and pregnancy outcomes in patients with multiple molar pregnancies. Material and Methods: Three unrelated cases with recurrent molar pregnancies are included in this study. None of the patients had a known family history of molar pregnancy. Clinical findings and follow-up results are documented. Sanger sequencing is used to reveal genetic defects in exons and exon-intron boundaries of NLRP7 and KHDC3L genes. Results: NLRP7 pathogenic variants were found in all three cases. In two cases, homozygous, c.2471+1G>A canonical splice cite variant was identified and in one case a homozygous, c.2571dupC (p.Ile858HisfsTer11) frameshift variant was identified. No variant in the KHDC3L gene was found in any case. In all cases, the development of gestational trophoblastic neoplasia complicated the clinical course and the treatment plans. Conclusions: We found that defects of the NLRP7 gene are principally responsible for etiology in our region, and the mutation profile suggests a founder effect in the Turkish population. We suggest early genetic diagnosis and counseling in molar pregnancies and recommend close follow-up in terms of conversion to gestational trophoblastic neoplasia.

Biallelic NLRP7 variants in patients with recurrent hydatidiform mole: A review and expert consensus.

Hydatidiform mole (HM) is an abnormal human pregnancy characterized by excessive growth of placental trophoblasts and abnormal early embryonic development. Following a first such abnormal pregnancy, the risk for women of successive molar pregnancies significantly increases. To date variants in seven maternal-effect genes have been shown to cause recurrent HMs (RHM). NLRP7 is the major causative gene for RHM and codes for NOD-like receptor (NLR) family pyrin domain containing 7, which belongs to a family of proteins involved in inflammatory disorders. Since its identification, all NLRP7 variants have been recorded in Infevers, an online registry dedicated to autoinflammatory diseases (https://infevers.umai-montpellier.fr/web/). Here, we reviewed published and unpublished recessive NLRP7 variants associated with RHM, scored their pathogenicity according to the American College of Medical Genetics classification, and recapitulated all functional studies at the level of both the patients and the conceptions. We also provided data on further variant analyses of 32 patients and genotypes of 36 additional molar pregnancies. This comprehensive review integrates published and unpublished data on NLRP7 and aims at guiding geneticists and clinicians in variant interpretation, genetic counseling, and management of patients with this rare condition.

Genetic screening of Chinese patients with hydatidiform mole by whole-exome sequencing and comprehensive analysis.

PURPOSE: We aim to explore if there are any other candidate genetic variants in patients with a history of at least one hydatidiform mole (HM) besides the well-known variants in NLRP7 and KHDC3L. METHODS: The diagnosis of HM type was based on histopathology, and available HM tissues were collected for short tandem repeat (STR) genotyping to verify the diagnosis. DNA extracted from blood samples or decidual tissues of the 78 patients was subjected to whole-exome sequencing (WES). RESULTS: We identified five novel variants in NLRP7, two novel variants in KHDC3L, and a chromosome abnormality covering the KHDC3L locus among patients with HM. We found that patients with HM who carried heterozygous variants in KHDC3L had a chance of normal pregnancy. We also detected four novel genetic variants in candidate genes that may be associated with HM. CONCLUSION: Our study enriched the spectrum of variants in NLRP7 and KHDC3L in Chinese HM patients and provided a new outlook on the effects of heterozygous variants in KHDC3L. The novel candidate genetic variants associated with HMs reported in this study will also contribute to further research on HMs.

Detection of Parental Contribution to Molar Genome Leads to Diagnosis of Recurrent Hydatidiform Mole in a Family with NLRP7 Variants.

Introduction: Genetically, complete hydatidiform mole (CHM) is androgenetic diploid, containing two sets of paternal chromosomes. In most cases, recurrent HM (RHM) is CHM but has diploid biparental chromosome constitution. Case report: We report a mother with RHM, both with biparental diploidy. The mother was compound heterozygous for two variants, c.1720dup, p.(C574Lfs*4) and c.2165A > G, p.(D722G) of the NLRP7 gene, as was a brother who fathered 2 normal pregnancies. Conclusion: The genotype study should be obtained for patients of CHM, even in their first pregnancy, followed by genetic screening for maternal-effect variants in those with biparental moles. This strategy will identify patients in their first pregnancy with HM that have a decreased chance for a normal pregnancy, to allow genetic counseling, perhaps utilizing a donor egg.

Novel pathogenic variants in NLRP7, NLRP5, and PADI6 in patients with recurrent hydatidiform moles and reproductive failure.

Recurrent hydatidiform moles (RHMs) are human pregnancies with abnormal embryonic development and hyperproliferating trophoblast. Biallelic mutations in NLRP7 and KHDC3L, members of the subcortical maternal complex (SCMC), explain the etiology of RHMs in only 60% of patients. Here we report the identification of seven functional variants in a recessive state in three SCMC members, five in NLRP7, one in NLRP5, and one in PADI6. In NLRP5, we report the first patient with RHMs and biallelic mutations. In PADI6, the patient had four molar pregnancies, two of which had fetuses with various abnormalities including placental mesenchymal dysplasia and intra-uterine growth restriction, which are features of Beckwith-Wiedemann syndrome and Silver Russell syndrome, respectively. Our findings corroborate recent studies and highlight the common oocyte origin of all these conditions and the continuous spectrum of abnormalities associated with deficiencies in the SCMC genes.

NLRP7 variants in spontaneous abortions with multilocus imprinting disturbances from women with recurrent pregnancy loss.

PURPOSE: Comparative analysis of multilocus imprinting disturbances (MLIDs) in miscarriages from women with sporadic (SPL) and recurrent pregnancy loss (RPL) and identification of variants in the imprinting control gene NLRP7 that may lead to MLIDs. METHODS: Chorionic cytotrophoblast and extraembryonic mesoderm samples from first-trimester miscarriages were evaluated in 120 women with RPL and 134 women with SPL; 100 induced abortions were analyzed as a control group. All miscarriages had a normal karyotype. Epimutations in 7 imprinted genes were detected using methyl-specific PCR and confirmed with DNA pyrosequencing. Sequencing of all 13 exons and adjusted intron regions of the NLRP7 gene was performed. RESULTS: Epimutations in imprinted genes were more frequently detected (p < 0.01) in the placental tissues of miscarriages from women with RPL (7.1%) than in those of women with SPL (2.7%). The predominant epimutation was postzygotic hypomethylation of maternal alleles of imprinted genes (RPL, 5.0%; SPL, 2.1%; p < 0.01). The frequency of MLID was higher among miscarriages from women with RPL than among miscarriages from women with SPL (1.7% and 0.4%, respectively, p < 0.01). Variants in NLRP7 were detected only in miscarriages from women with RPL. An analysis of the parental origin of NLRP7 variants revealed heterozygous carriers in families with RPL who exhibited spontaneous abortions with MLIDs and compound heterozygosity for NLRP7 variants. CONCLUSION: RPL is associated with NLRP7 variants that lead to germinal and postzygotic MLIDs that are incompatible with normal embryo development. TRIAL REGISTRATION: Not applicable.

Abnormal processing of IL-1ß in NLRP7-mutated monocytes in hydatidiform mole patients.

NOD-like receptor pyrin 7 (NLRP7) has been identified as the major gene responsible for the recurrent hydatidiform mole (RHM). The immunological role of NLRP7 mutation in HM patients has not been conclusively demonstrated. Hence, we aim to demonstrate this role in our study. We followed 12 new patients with NLRP7 non-synonymous variations (NSVs) from date to date. Peripheral blood mononuclear cells (PBMCs) were collected separately from patients with and without NLRP7 mutation. Supernatant interleukin (IL)-1ß secretion, intracellular pro-IL-1ß and mature IL-1ß expressions were measured after 24 h lipopolysaccharide (LPS) stimulation. Plasmids with corresponding NSVs were generated to evaluate the ability of processing pro-IL-1ß into mature IL-1ß in vitro. Homozygous or compound heterozygous NLRP7 mutations secreted less IL-1ß in roots of abnormal intracellular pro-IL-1ß or mature IL-1ß, according to different domains. Plasmids with NSVs could also affect processing or/and trafficking together with caspase-1 and apoptosis-associated speck-like protein (ASC). Inflammasome-related NLRP7 mutation is a potential mechanism of RHM.

Pregnancy after oocyte donation in a patient with NLRP7 gene mutations and recurrent molar hydatidiform pregnancies.

Molar pregnancies are benign trophoblastic diseases associated with a risk of malignant transformation. If aetiology remains mostly unknown, the risk of recurrent molar pregnancy is around 1.5% after one molar pregnancy and around 25% after 2 molar pregnancies. In the later situation, genetic mutations have been described, increasing hugely this risk. In case of mutations, probability to obtain a normal pregnancy is estimated around 1.8%. We report the case of a Caucasian 30-year-old woman whose previous five spontaneous pregnancies had a negative outcome: a spontaneous miscarriage and then 4 complete hydatidiform moles. Genetic testing revealed that the patient carried two heterozygous mutations in the NLRP7 gene (c.2982-2A > G and Y318CfsX7). According to this, counselling was conducted to advocate for oocyte donation in order to obtain a normal pregnancy. This technique enabled a complication-free, singleton pregnancy that resulted in a healthy term live birth of a 2900 g female. Few months after delivery, the patient presented a new complete hydatidiform mole. Women presented with mutations in the NLRP7, KHDC3L or PADI6 genes are unlikely to obtain normal pregnancies, with a major risk of reproductive failure. In such a context, oocyte donation may be the best option. Only 4 normal pregnancies and deliveries have been published in this situation through this technique to our knowledge.

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.

Maternal variants in NLRP and other maternal effect proteins are associated with multilocus imprinting disturbance in offspring.

BACKGROUND: Genomic imprinting results from the resistance of germline epigenetic marks to reprogramming in the early embryo for a small number of mammalian genes. Genetic, epigenetic or environmental insults that prevent imprints from evading reprogramming may result in imprinting disorders, which impact growth, development, behaviour and metabolism. We aimed to identify genetic defects causing imprinting disorders by whole-exome sequencing in families with one or more members affected by multilocus imprinting disturbance. METHODS: Whole-exome sequencing was performed in 38 pedigrees where probands had multilocus imprinting disturbance, in five of whom maternal variants in NLRP5 have previously been found. RESULTS: We now report 15 further pedigrees in which offspring had disturbance of imprinting, while their mothers had rare, predicted-deleterious variants in maternal effect genes, including NLRP2, NLRP7 and PADI6. As well as clinical features of well-recognised imprinting disorders, some offspring had additional features including developmental delay, behavioural problems and discordant monozygotic twinning, while some mothers had reproductive problems including pregnancy loss. CONCLUSION: The identification of 20 putative maternal effect variants in 38 families affected by multilocus imprinting disorders adds to the evidence that maternal genetic factors affect oocyte fitness and thus offspring development. Testing for maternal-effect genetic variants should be considered in families affected by atypical imprinting disorders.

NLRP7 Is Involved in the Differentiation of the Decidual Macrophages.

Macrophage polarization, regulated appropriately, may play important roles in successful pregnancy. In the face of the vital roles of decidua macrophages in pregnancy, it is insufficient to recognize the trigger of macrophage differentiation and polarization. We aimed to explore the link between the NLRP7 gene and macrophage polarization in human deciduas. Here, we enrolled the endometrial tissues from eight pregnant women in the first trimester. We found that NLRP7 was abundant in endometrial tissues and that NLRP7 was expressed in decidual macrophages of the first-trimester pregnancy. NLRP7 was predominately expressed in the decidual M2 macrophages, as compared with the M1 macrophages. Furthermore, our results suggest that NLRP7 is associated with decidual macrophage differentiation. NLRP7 over-expression suppresses the expression of M1 markers and enhances the expression of the M2 markers. Considering that NLRP7 relates to decidualization and macrophage differentiation, we propose that NLRP7 is a primate-specific multitasking gene to maintain endometrial hemostasis and reproductive success. This finding may pave the way for therapies of pathological pregnancies.

Recurrent complete hydatidiform mole: where we are, is there a safe gestational horizon? Opinion and mini-review.

Benign hydatidiform mole, complete or partial, is the most common type of gestational trophoblastic disease (GTD) characterised by excessive trophoblastic proliferation and abnormal embryonic development. Although most complete hydatidiform moles (CHMs) are diploid androgenetic, a few cases of CHMs are biparental, characterised by recurrence and familial clustering. In these rare cases, mutations in NLRP7 or KHDC3L genes, associated with maternal imprinting defects, have been implicated. Current data regarding future pregnancy options in hydatidiform moles are discussed and our opinion is presented based on an incidence that took place in our hospital with a woman with consecutive molar pregnancies. In recurrent hydatidiform moles, DNA testing should be performed and when NLRP7 or KHDC3L mutation are detected, oocyte donation should be proposed as an option to maximise woman's chances of having a normal pregnancy.

NLRP7 contributes to in vitro decidualization of endometrial stromal cells.

BACKGROUND: Nucleotide-binding oligomerization domain (NACHT), leucine rich repeat (LRR) and pyrin domain (PYD) 7 containing protein, NLRP7, is a member of the NLR family which serves as innate immune sensors. Mutations and genetic variants of NLRP7 have been found in women with infertility associated conditions, such as recurrent hydatidiform mole, recurrent miscarriage, and preeclampsia. Decidualization of endometrial stromal cells is a hallmark of tissue remodeling to support embryo implantation and proper placental development. Given defective decidualization has been implicated in miscarriage as well as preeclampsia, we aimed to explore the link between the NLRP7 gene and decidualization. METHODS: Endometrial samples obtained from pregnant women in the first trimester and non-pregnant women were used to study NLRP7 expression pattern. The human telomerase reverse transcriptase (hTERT)-immortalized human endometrial stromal cells (T-HESCs) were used to study the effect of NLRP7 on decidualization. Decidualization of T-HESCs was induced with 1 µM medroxyprogesterone acetate (MPA) and 0.5 mM 8-bromoadenosine 3':5'-cyclic monophosphate (8-Br-cAMP). siRNA was used to knock down NLRP7 while lentiviral vectors were used to overexpress NLRP7 in cells. NLRP7 expression was detected by immunofluorescence, qRT-PCR, and Western blotting. Decidualization markers, Insulin-like growth factor-binding protein 1 (IGFBP-1) and prolactin (PRL), were detected by qRT-PCR and ELISA. Nuclear translocation of NLRP7 was detected by the subcellular fractionation and confocal microscopy. The effect of NLRP7 on progesterone receptor (PR) activity was evaluated by a reporter system. RESULTS: NLRP7 was up-regulated in the decidual stromal cells of human first-trimester endometrium. After in vitro decidualization, T-HESCs presented with the swollen phenotype and increased expressions of IGFBP-1 and PRL. Knockdown or over-expression of NLRP7 reduced or enhanced the decidualization, respectively, according to the expression level of IGFBP-1. NLRP7 was found to translocate in the nucleus of decidualized T-HESCs and able to promote PR activity. CONCLUSIONS: NLRP7 was upregulated and translocated to the nucleus of the endometrial stromal cells in an in vitro decidualization model. Overexpressed NLRP7 promoted the IGFBP-1 expression and PR reporter activation. IGFBP-1 expression decreased with the knockdown of NLRP7. Therefore, we suggest that NLRP7 contributes to in vitro decidualization of endometrial stromal cells.

NLRP7 and KHDC3L, the two maternal-effect proteins responsible for recurrent hydatidiform moles, co-localize to the oocyte cytoskeleton.

STUDY QUESTION: What is the subcellular localization in human oocytes and preimplantation embryos, of the two maternal-effect proteins, NLRP7 and KHDC3L, responsible for recurrent hydatidiform moles (RHMs)? SUMMARY ANSWER: NLRP7 and KHDC3L localize to the oocyte cytoskeleton and are polar and absent from the cell-to-cell contact region in early preimplantation embryos. WHAT IS KNOWN ALREADY: NLRP7 and KHDC3L expression has been described at the RNA level in some stages of human oocytes and preimplantation embryos and at the protein level by immunohistochemistry in human and bovine ovaries. NLRP7 and KHDC3L co-localize to the microtubule organizing center and/or the Golgi apparatus in human hematopoietic cells. STUDY DESIGN, SIZE, DURATION: A total of 164 spare human oocytes and embryos from patients undergoing in vitro fertilization were used. PARTICIPANTS/MATERIALS, SETTING, METHODS: Oocytes and early cleavage-stage embryos were fixed, immunostained with NLRP7 and/or KHDC3L antibodies, and analyzed using high-resolution confocal immunofluorescence and electron microscopies. MAIN RESULTS AND THE ROLE OF CHANCE: NLRP7 and KHDC3L localize to the cytoskeleton and are predominant at the cortical region in growing oocytes. After the first cellular division, these two maternal-effect proteins become asymmetrically confined to the outer cortical region and excluded from the cell-to-cell contact region until the blastocyst stage where NLRP7 and KHDC3L homogeneously redistribute to the cytoplasm and the nucleus, respectively. LIMITATIONS, REASONS FOR CAUTION: We could not analyze fresh human oocytes and embryos. The analyzed materials were donated by patients undergoing assisted reproductive technologies and released for research 1-3 days after their collection and the transfer of embryos to the patients. WIDER IMPLICATIONS OF THE FINDINGS: Our study is the first comprehensive and high-resolution localization of the only two known maternal-effect proteins, NLRP7 and KHDC3L, in human oocytes and preimplantation embryos. Our data contribute to a better understanding of the roles of these two proteins in the integrity of the oocytes, post-zygotic divisions, and cell-lineage differentiation. STUDY FUNDING/COMPETING INTERESTS: This work was supported by the Canadian Institute of Health Research (86546 to R.S.); E.A. was supported by fellowships from the Research Institute of the McGill University Health Centre and a CREATE award from the Réseau Québécois en Reproduction. All authors declare no conflict of interest.

No evidence for mutations in NLRP7, NLRP2 or KHDC3L in women with unexplained recurrent pregnancy loss or infertility.

STUDY QUESTION: Are mutations in NLRP2/7 (NACHT, LRR and PYD domains-containing protein 2/7) or KHDC3L (KH Domain Containing 3 Like) associated with recurrent pregnancy loss (RPL) or infertility? SUMMARY ANSWER: We found no evidence for mutations in NLRP2/7 or KHDC3L in unexplained RPL or infertility. WHAT IS KNOWN ALREADY: Mutations in NLRP7 and KHDC3L are known to cause biparental hydatidiform moles (BiHMs), a rare form of pregnancy loss. NLRP2, while not associated with the BiHM pathology, is known to cause recurrent Beckwith Weidemann Syndrome (BWS). STUDY DESIGN, SIZE, AND DURATION: Ninety-four patients with well characterized, unexplained infertility were recruited over a 9-year period from three IVF clinics in Sweden. Blood samples from 24 patients with 3 or more consecutive miscarriages of unknown etiology were provided by the Recurrent Miscarriage Clinic at St Mary's Hospital, London, UK. PARTICIPANTS/MATERIALS, SETTING, METHODS: Patients were recruited into both cohorts following extensive clinical studies. Genomic DNA was isolated from peripheral blood and subject to Sanger sequencing of NLRP2, NLRP7 and KHDC3L. Sequence electropherograms were analyzed by Sequencher v5.0 software and variants compared with those observed in the 1000 Genomes, single nucleotide polymorphism database (dbSNP) and HapMap databases. Functional effects of non-synonymous variants were predicted using Polyphen-2 and sorting intolerant from tolerant (SIFT). MAIN RESULTS AND THE ROLE OF CHANCE: No disease-causing mutations were identified in NLRP2, NLRP7 and KHDC3L in our cohorts of unexplained infertility and RPL. LIMITATIONS, REASONS FOR CAUTION: Due to the limited patient size, it is difficult to conclude if the low frequency single nucleotide polymorphisms observed in the present study are causative of the phenotype. The design of the present study therefore is only capable of detecting highly penetrant mutations. WIDER IMPLICATIONS OF THE FINDINGS: The present study supports the hypothesis that mutations in NLRP7 and KHDC3L are specific for the BiHM phenotype and do not play a role in other adverse reproductive outcomes. Furthermore, to date, mutations in NLRP2 have only been associated with the imprinting disorder BWS in offspring and there is no evidence for a role in molar pregnancies, RPL or unexplained infertility. STUDY FUNDING/COMPETING INTERESTS: This study was funded by the following sources: Estonian Ministry of Education and Research (Grant SF0180044s09), Enterprise Estonia (Grant EU30020); Mentored Resident research project (Department of Obstetrics and Gynecology, Baylor College of Medicine); Imperial NIHR Biomedical Research Centre; Grant Number C06RR029965 from the National Center for Research Resources (NCCR; NIH). No competing interests declared.

Risk of recurrent molar pregnancies following complete and partial hydatidiform moles.

STUDY QUESTION: What is the risk of further molar pregnancies for women with one or more hydatidiform moles (HM) in relation to molar subtype. SUMMARY ANSWER: Women with a complete hydatidiform mole (CM) have a 1 in 100 and 1 in 4 risk of further CM after one or two consecutive CM, respectively, while women with a partial hydatidiform mole (PM) have only a small increase in risk for further molar pregnancies. WHAT IS KNOWN ALREADY: Women with a molar pregnancy have an increased risk of further HM. A small subgroup of women with recurrent HM has an autosomal recessive condition, familial recurrent hydatidiform moles (FRHM), that predisposes them to molar pregnancies. STUDY DESIGN, SIZE, DURATION: A retrospective study of subsequent pregnancies in 16 000 women registered at a centralized referral centre, with a CM or PM, between 1990 and 2009. PARTICIPANTS/MATERIALS, SETTING, METHODS: One hundred and sixty-six women with two or more molar pregnancies were identified from electronic records and patient notes. Histopathological features of all molar tissue were reviewed in these cases and genotyping performed where diagnosis was not possible on the basis of histopathological features alone. In addition, genotyping of molar tissue was performed in all cases of women with three or more CM to establish whether the tissue was diploid and biparental or androgenetic. MAIN RESULTS AND THE ROLE OF CHANCE: This study confirms an increased recurrence risk of ∼1% for a second molar pregnancy and in addition that this risk is associated with CM rather than PM. The data further indicate that the risk of a third HM is associated almost exclusively with CM and enabled an estimate that 1 in 640 women registered with a CM has the rare condition FRHM. The study also found that there was no significant difference between the risk of developing gestational trophoblastic neoplasia (GTN) for typical sporadic CM and the diploid biparental CM associated with FRHM (GTN; proportion difference 0.05, Z = 0.87, P = 0.29). LIMITATIONS, REASONS FOR CAUTION: While pathology was reviewed for all women with two or more molar pregnancies, not all cases registered underwent central review particularly those women registered in the early 1990s. It is therefore possible that the total number of CM and PM may differ slightly from that stated. While women were followed for a minimum of 5 years, it is possible that some women may subsequently have further molar pregnancies that will not have been included in the present study. WIDER IMPLICATIONS OF THE FINDINGS: This is the largest study to date on recurrence for molar pregnancies, and as such provides the most detailed information so far regarding the risk of further molar pregnancies for women with a PM or CM. Furthermore, the data provide new insights into the incidence of the rare autosomal recessive condition, FRHM, important information for counselling women with molar pregnancies. STUDY FUNDING/COMPETING INTERESTS: No competing interests declared. No funding was obtained for this study.

Live births in women with recurrent hydatidiform mole and two NLRP7 mutations.

Hydatidiform mole (HM) is an aberrant human pregnancy with abnormal embryonic development and excessive proliferation of the trophoblast. Recessive mutations in NLRP7 are responsible for recurrent HM (RHM). Women with recessive NLRP7 mutations fail to have normal pregnancies from spontaneous conceptions with the exception of three out of 131 reported patients. Because there is no treatment for RHM and maternal-effect genes are needed in the oocytes to sustain normal embryonic development until the activation of the embryonic genome, one patient with recessive NLRP7 mutations tried ovum donation and achieved a successful pregnancy. This study reports three additional live births from donated ova to two patients with recessive NLRP7 mutations. The occurrence of two live births from spontaneous conceptions to two other patients is also reported. The reproductive outcomes and mutations of all reported patients were reviewed and it was found that live births are associated with some missense mutations expected to have mild functional consequences on the protein. The data support a previous observation that ovum donation appears the best management option for these patients to achieve normal pregnancies and provide an explanation for the rare occurrence of live births from natural spontaneous conceptions in patients with two NLRP7 mutations.

Comprehensive genotype-phenotype correlations between NLRP7 mutations and the balance between embryonic tissue differentiation and trophoblastic proliferation.

BACKGROUND: Hydatidiform mole (HM) is a human pregnancy with excessive trophoblastic proliferation and abnormal embryonic development that may be sporadic or recurrent. In the sporadic form, the HM phenotype is driven by an abnormal ratio of paternal to maternal genomes, whereas in the recurrent form, the HM phenotype is caused by maternal-recessive mutations, mostly in NLRP7, despite the diploid biparental origin of the HM tissues. In this study, we characterised the expression of the imprinted, maternally expressed gene, CDKN1C (p57(KIP2)), the genotype, and the histopathology of 36 products of conception (POC) from patients with two defective alleles in NLRP7 and looked for potential correlations between the nature of the mutations in the patients and the various HM features. METHODS/RESULTS: We found that all the 36 POCs are diploid biparental and have the same parental contribution to their genomes. However, some of them expressed variable levels of p57(KIP2) and this expression was strongly associated with the presence of embryonic tissues of inner cell mass origin and mild trophoblastic proliferation, which are features of triploid partial HMs, and were associated with missense mutations. Negative p57(KIP2) expression was associated with the absence of embryonic tissues and excessive trophoblastic proliferation, which are features of androgenetic complete HMs and were associated with protein-truncating mutations. CONCLUSIONS: Our data suggest that NLRP7, depending on the severity of its mutations, regulates the imprinted expression of p57(KIP2) and consequently the balance between tissue differentiation and proliferation during early human development. This role is novel and could not have been revealed by any other approach on somatic cells.

NLRP7 inter-domain interactions: the NACHT-associated domain is the physical mediator for oligomeric assembly.

Mutations in NLRP7 (NOD-like-receptor family, pyrin domain containing 7) are responsible for a type of recurrent pregnancy loss known as recurrent hydatidiform mole (HYDM1). This condition is characterized by abnormal growth of the placenta, a lack of proper embryonic development and abnormal methylation patterns at multiple imprinted loci in diploid biparental molar tissues. The role of NLRP7 protein in the disease manifestation is currently not clear. In order to better understand how the effects of HYDM1 are associated with mutations on the structure of NLRP7, we performed an inter-domain interaction screen using a yeast two-hybrid system. Additionally, we generated in silico structural models of NLRP7 in its non-activated and activated forms. Our observations from the yeast two-hybrid screen and modeling suggest that the NACHT-associated domain (NAD) of the NLRP7 protein is central to its oligomeric assembly. Upon activation, the NAD and a small part of the leucine rich repeat (LRR) of one molecule emerged out of the protective LRR domain and interact with the NACHT domain of the second molecule to form an oligomer. Furthermore, we investigated the molecular basis for the pathophysiological effect of four missense mutations, three HYDM1-causing and one rare non-synonymous variant, on the protein using confocal microscopy of transiently transfected NLRP7 in HEK293T cells and in silico structural analysis. We found that with the two clinically severe missense mutations, L398R and R693W, the normal molecule to molecule interaction was apparently affected thus decreasing their oligomerization potential while aggresome formation was increased; these changes could disturb the normal downstream functions of NLRP7 and therefore be a possible molecular effect underlying their pathophysiological impact.