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.

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.

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.

Founder Effect of KHDC3L, p.M1V Mutation, on Iranian Patients with Recurrent Hydatidiform Moles.

BACKGROUND: Recurrent hydatidiform moles (RHMs) are an unusual pregnancy with at least two molar gestations that are associated with abnormal proliferation of trophoblastic tissue and a failure in the embryonic tissues development. Three maternal-effect genes, including NLRP7, KHDC3L, and PADI6 have been identified as the cause of RHMs. The present study aimed to understand the association of a founder mutation with the incidence and prevalence of a disease in different individuals of a population. METHODS: 14 unrelated Iranian patients with recurrent reproductive wastage, including at least two HMs, entered this study. In order to find a possible mutation in KHDC3L, all the 14 samples were Sanger sequenced. For haplotype analysis, three single nucleotide polymorphisms (SNPs) were selected with highest Minor Allele Frequency along KHDC3L. RESULTS: A common KHDC3L mutation with the same haplotype was identified in four out of 14 patients with RHM. Regarding the present study, c.1A>G is the highest reported mutation in KHDC3L so far and is also the first report of the homozygous state that has led to RHM. CONCLUSION: c.1A>G mutation in KHDC3L is the highest reported mutation around the world. Our data also demonstrated the presence of founder effects for this particular mutation in Iranian populations. These data suggest that the high frequency of this mutation is potentially responsible for a higher rate of RHM in Iran.

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.

Novel mutations in genes encoding subcortical maternal complex proteins may cause human embryonic developmental arrest.

Successful human reproduction initiates from normal gamete formation, fertilization and early embryonic development. Abnormalities in any of these steps will lead to infertility. Many infertile patients undergo several failures of IVF and intracytoplasmic sperm injection (ICSI) cycles, and embryonic developmental arrest is a common phenotype in cases of recurrent failure of IVF/ICSI attempts. However, the genetic basis for this phenotype is poorly understood. The subcortical maternal complex (SCMC) genes play important roles during embryonic development, and using whole-exome sequencing novel biallelic mutations in the SCMC genes TLE6, PADI6 and KHDC3L were identified in four patients with embryonic developmental arrest. A mutation in TLE6 was found in a patient with cleaved embryos that arrested on day 3 and failed to form blastocysts. Two patients with embryos that arrested at the cleavage stage had mutations in PADI6, and a mutation in KHDC3L was found in a patient with embryos arrested at the morula stage. No mutations were identified in these genes in an additional 80 patients. These findings provide further evidence for the important roles of TLE6, PADI6 and KHDC3L in embryonic development. This work lays the foundation for the genetic diagnosis of patients with recurrent IVF/ICSI failure.

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.

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.

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.

Genetics and Genomics of Gestational Trophoblastic Disease.

This article focuses on hydatidiform mole (HM), which is the most common form of gestational trophoblastic disease and the most studied at the genomic and genetic levels. We summarize current laboratory methods to diagnose HM, discuss their limitations and advantages, and share the lessons we have learned. We also provide an overview of the history of recurrent HM, their known genetic etiologies, and the mechanisms of their formation.

NLRP7 or KHDC3L genes and the etiology of molar pregnancies and recurrent miscarriage.

Women with mutation in both alleles of the NLRP7 or C6orf221/KHDC3L genes are predisposed to diploid biparental moles, but it has also been suggested that mutation in these genes can predispose to diploid androgenetic or triploid moles and to other kinds of reproductive wastage. We have investigated the association between molar pregnancy and recurrent miscarriages regarding changes in the NLRP7 and C6orf221/KHDC3L genes. Our study group can be divided into three sub-cohorts: (i) women having had at least one molar pregnancy and at least two non-mole miscarriages, (ii) women having had recurrent androgenetic hydatidiform moles and (iii) women having had one diploid androgenetic hydatidiform mole and a relative having had a hydatidiform mole (familial hydatidiform moles). We observed a statistically non-significant tendency of non-synonymous variants in NLRP7 to be more frequent in women with familial hydatidiform mole and in women with female family members with hydatidiform mole or non-mole miscarriage compared with women with no family history of mole or miscarriage. However, we did not find any unequivocal pathogenic mutations (the term 'unequivocal pathogenic mutations' refers to mutations that indubitably have a pathogenic effect on the affected woman) in NLRP7 or C6orf221/KHDC3L in any of the women in the study group. This indicates that recurrent miscarriages plus hydatidiform mole, recurrent androgenetic hydatidiform moles and familial androgenetic hydatidiform moles in general do not have the same monogenetic etiology as familiar diploid biparental moles.

A familial case of recurrent hydatidiform mole with p.Asp108Ilefs∗30 causing mutation in KHDC3L: A genetic and clinical report.

OBJECTIVE: Hydatidiform mole (HM) is defined by trophoblastic proliferation and vesicular enlargement of placental villi in which, KHDC3L gene plays a causal role. CASE REPORT: This report presents a clinical review and genetic screening for p.Asp108Ilefs∗30 mutation in KHDC3L gene in an affected woman with a previous history of HM and three siblings with a history of HM. Pathological examination of molar pregnancy in proband confirmed a typical complete HM (CHM). Also, DNA extraction was done, polymerase chain reaction was carried out and then sequencing was performed by the Sanger sequencing method. The screened mutation was found in all three sisters in a homozygous state. CONCLUSION: Egg donation is suggested for having viable children in these patients with the lowest risk of inadvertent damage.

KH domain containing 3 like (KHDC3L) frame-shift mutation causes both recurrent pregnancy loss and hydatidiform mole.

OBJECTIVE: Recurrent pregnancy loss (RPL) is a common infertility-related complication that affects approximately 1-3 % of women worldwide. Known causes of etiology are found in approximately half the cases but the other half remain unexplained. It is estimated that several thousands of genes contribute to reproductive success in mammals and the genetic causes of RPL cannot be fully addressed through targeted genetic tests. In recent years, massive parallel sequencing technologies has helped discovering many causal mutations in hereditary diseases such as RPL. STUDY DESIGN: Using whole-exome sequencing (WES), we studied a large multiplex consanguineous family with multiple cases of RPL and hydatidiform moles (HM). In addition, targeted Sanger sequencing was applied to 40 additional non-related individuals with RPL. RESULTS: The use of WES permitted to identify the pathogenic variant in KHDC3L (c.322_325delGACT) in related who experienced RPL with or without HM. Sanger sequencing confirmed the segregation of the mutation throughout the pedigree and permitted to establish this variant as the genetic cause responsible for RPL and HM in this family. CONCLUSION: KHDC3L is well established as a susceptibility gene for HM but we confirmed here that KHDC3L deleterious variants can also induce RPL. In addition, we observed a genotype-phenotype correlation, demonstrating that women with a truncating KHDC3L homozygous variant could not sustain a pregnancy and often had pregnancy losses mainly due to HM while those with the same heterozygous variant could have children but often endured RPL with no HM.

Exome-Sequencing Identifies Novel Genes Associated with Recurrent Pregnancy Loss in a Chinese Cohort.

Recurrent pregnancy loss (RPL) is a common reproductive problem affecting around 5% of couples worldwide. At present, about half of RPL cases remained unexplained. Previous studies have suggested an important role for genetic determinants in the etiology of RPL. Here, we performed whole-exome sequencing (WES) analysis on 100 unrelated Han Chinese women with a history of two or more spontaneous abortions. We identified 6736 rare deleterious nonsynonymous variants across all patients. To focus on possible candidate genes, we generated a list of 95 highly relevant genes that were functionally associated with miscarriage according to human and mouse model studies, and found 35 heterozygous variants of 28 RPL-associated genes in 32 patients. Four genes (FOXA2, FGA, F13A1, and KHDC3L) were identified as being strong candidates. The FOXA2 nonsense variant was for the first time reported here in women with RPL. FOXA2 knockdown in HEK-293T cells significantly diminished the mRNA and protein expression levels of LIF, a pivotal factor for maternal receptivity and blastocyst implantation. The other genes, with 29 variants, were involved in angiogenesis, the immune response and inflammation, cell growth and proliferation, which are functionally important processes for implantation and pregnancy. Our study identified several potential causal genetic variants in women with RPL by WES, highlighting the important role of genes controlling coagulation, confirming the pathogenic role of KHDC3L and identifying FOXA2 as a newly identified causal gene in women with RPL.

A Novel Mutation in NLRP7 Related to Recurrent Hydatidiform Mole and Reproductive Failure.

BACKGROUND: Hydatidiform mole (HM) is an abnormal human pregnancy with excessive trophoblastic proliferation and abnormal embryonic development, dividing into two complete HM (CHM) and partial HM (PHM) groups. One subcategory of the CHMs is recurrent and familial, which is known as biparental HM (BiHMs) or recurrent HM (RHM). NLRP7, KHDC3L and PADI6 are maternal-effect genes involved in RHMs. NLRP7 is a major gene responsible for RHMs. This study was performed on patients with molar pregnancies and miscarriage. The aim of this study was to genetic screen for mutations in NLRP7 and KHDC3L genes in an affected woman with previous history of 5RHM and the sibling with history of miscarriage. MATERIALS AND METHODS: In this experimental study, DNA was extracted from blood samples. KHDC3L and NLRP7 were polymerase chain reaction (PCR) amplified. The PCR products were purified and Sanger sequenced. RESULTS: In this study, there is no mutation in KHDC3L gene but a novel mutation was identified in the NACHT domain of NLRP7 gene. Patient with five recurrent moles had this mutation in the homozygous state while her sister with one miscarriage and one normal child showed this mutation in the heterozygous state. CONCLUSION: In this study, we identified a new mutation in NLRP7 gene of a patient with recurrent HM. Following egg donation, this patient has a normal boy. The sister of this patient with heterozygous mutation has a spontaneous abortion and one normal child that confirm the impact of a defective allele of NLRP7 on reproductive wastage in a recent finding.

Clinical and genetic-epignetic aspects of recurrent hydatidiform mole: A review of literature.

Hydatidiform Mole (HM) is the most common form of Gestational Trophoblastic Disease (GTD), defined by hyper-proliferation of trophoblastic cells. HM is typified as abnormal proliferation of extraembryonic trophoblastic (placental) tissues and failure of embryonic tissues development and is the only GTD with Mendelian inheritance, which can reoccur in different pregnancies. Moles are categorized into Complete Hydatidiform Moles (CHM) or Partial Hydatidiform Moles (PHM) and a rare familial trait, which forms a CHM and despite having androgenetic pattern, shows normal biparental inheritance, conceived from one sperm and egg. Recessive maternal-effect mutations in NLRP7 (NACHT, leucine rich repeat and PYD containing 7) and KHDC3L (KH Domain Containing 3-Like) genes have been shown to be responsible for Recurrent Hydatidiform Moles (HYDM1 MIM# 231090 when is caused by mutation in the NLRP7 gene and HYDM2 MIM#614293 when is caused by mutation in the KHDC3L gene). Methylation aberration in multiple maternally imprinted genes is introduced as the cause of Recurrent HYDM pathology. The current article reviews the histopathology, risk factors, and genetic and epigenetic characteristics of Recurrent HYDMs.

Genetics and Epigenetics of Recurrent Hydatidiform Moles: Basic Science and Genetic Counselling.

Gestational trophoblastic disease (GTD) is a group of conditions that originate from the abnormal hyperproliferation of trophoblastic cells, which derive from the trophectoderm, the outer layer of the blastocyst that would normally develop into the placenta during pregnancy. GTDs encompass hydatidiform mole (HM) (complete and partial), invasive mole, gestational choriocarcinoma, placental-site trophoblastic tumor, and epithelioid trophoblastic tumor. Of these, the most common is HM, and it is the only one that has been reported to recur in the same patients from independent pregnancies, which indicates the patients' genetic predisposition. In addition, HM is the only GTD that segregates in families according to Mendel's laws of heredity, which made it possible to use rare familial cases of recurrent HMs (RHMs) to identify two maternal-effect genes, NLRP7 and KHDC3L, responsible for this condition. Here, we recapitulate current knowledge about RHMs and conclude with the role and benefits of testing patients for mutations in the known genes.

Absence of KHDC3L mutations in Chinese patients with recurrent and sporadic hydatidiform moles.

To date, two maternal-effect genes have been shown to play causal roles in recurrent hydatidiform moles (RHMs). NLRP7, a major gene for this condition, codes for a nucleotide-binding oligomerization domain-like receptor and is mutated in 48 to 60% of patients with RHMs. KHDC3L is a recently identified gene that is mutated in 14% of NLRP7-negative patients. We screened KHDC3L for mutations in a total of 101 Chinese patients, 15 with at least two hydatidiform moles, 16 with at least two reproductive losses including one hydatidiform mole, and 70 with one hydatidiform mole and no other form of reproductive loss, but did not find any mutation. Our data favor the causal role of KHDC3L in a minority of RHM cases, demonstrate its noninvolvement in other forms of reproductive loss, and indicate the presence of other unidentified genes that cause or increase patients' susceptibility to RHMs in the Chinese population.

Novel NLRP7 mutations in familial recurrent hydatidiform mole: are NLRP7 mutations a risk for recurrent reproductive wastage?

OBJECTIVE: Familial recurrent hydatidiform mole is an exceedingly rare clinical condition. Affected women are predisposed to molar pregnancies of diploid, biparental origin rather than androgenetic origin. At present, NLRP7 and KHDC3L (C6orf221) are the only genes known to be associated with familial recurrent hydatidiform mole. This study investigated the genetic dispositions in two large Turkish families with recurring molar conceptuses. STUDY DESIGN: Copy number variation analysis was performed followed by NLRP7 gene sequencing. The finding of a mono-allelic condition in one family led to investigation of the adjacent NLRP2 gene and recently associated KHDC3L gene. Sampled molar tissues were genotyped using microsatellite markers. RESULTS: In one family, a homozygous single nucleotide insertion that caused a frameshift leading to an early stop codon, c.2940_2941insC (p.Glu981ArgfsX13), was identified in the affected sisters. In the other family, a heterozygous 60-kb deletion eliminating substantial portions of the NLRP2 and NLRP7 genes on one allele was found. Screening of NLRP2 and KHDC3L genes revealed no alterations that were considered to be pathological. Genotyping of six independent molar conceptions revealed that five were of diploid, biparental origin and one was of diandric, triploid origin. CONCLUSIONS: Two novel protein-truncating mutations in the NLRP7 gene were found to be associated with familial recurrent hydatidiform mole. Mutations in the NLRP7 gene causing recurrent biparental hydatidiform mole may also be associated with other forms of recurrent reproductive wastage.