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.

Application of next-generation sequencing to preimplantation genetic testing for recurrent hydatidiform mole patients

PURPOSE

To study the application of next-generation sequencing on preimplantation genetic testing for recurrent hydatidiform mole patients.

METHODS

A total of ten recurrent hydatidiform mole patients aged 27-34 years with a history of at least twice hydatidiform moles and no normal pregnancy were collected from 2019 to 2020. The diagnosis of hydatidiform mole type was clarified using short tandem repeat genotyping on products of conception, and whole-exome sequencing was applied for all patients and their partners. Seven recurrent hydatidiform mole patients with complete hydatidiform mole/partial hydatidiform mole type among previous hydatidiform mole tissues and no Pathogenetic/Likely pathogenetic/Uncertain significance variants in NLRP7/KHDC3L/MEI1/C11orf80 underwent a procedure of preimplantation genetic testing. Next-generation sequencing for analyzing the copy number variants and the numbers of heterozygous single nucleotide polymorphism was adopted to clarify the ploidy and parental origin of the embryo chromosomes in vitro. Embryos with biparental diploidy were selected for transfer.

RESULTS

Seven patients have undergone the procedure of preimplantation genetic testing, and twenty-three embryos were obtained, among which 82.6% (n = 19) were identified transferrable and 17.4% (n = 4) were identified aneuploid. Two patients have delivered healthy babies and another is currently in the second trimester after transfer.

CONCLUSION

Analyzing the copy number variants and the numbers of heterozygous single nucleotide polymorphism on the basis of next-generation sequencing can be utilized in the procedure of preimplantation genetic testing among part of recurrent hydatidiform mole patients. The current study is effective to reduce the occurrence of hydatidiform mole with improved clinical strategy, the advanced testing technology and analysis methods, as three of seven patients have conceived or delivered successfully.

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.

A novel NLRP7 protein-truncating mutation associated with discordant and divergent p57 immunostaining in diploid biparental and triploid digynic moles

NLRP7 is a maternal-effect gene that has a primary role in the oocyte. Its biallelic mutations are a major cause for recurrent diploid biparental hydatidiform moles (HMs). Here, we describe the full characterization of four HMs from a patient with a novel homozygous protein-truncating mutation in NLRP7. We found that some HMs have features of both complete and partial moles. Two HMs expressed p57 in the cytotrophoblast and stromal cells and exhibited divergent and discordant immunostaining. Microsatellite DNA-genotyping demonstrated that two HMs are diploid biparental and one is triploid digynic due to the failure of meiosis II. FISH analysis demonstrated triploidy in the cytotrophoblast and stromal cells in all villi. Our data highlight the atypical features of HM from patients with recessive NLRP7 mutations and the important relationship between NLRP7 defects in the oocyte and p57 expression that appear to be the main contributor to the molar phenotype regardless of the zygote genotype.

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.

Recurrent familial hydatidiform mole - a rare clinical problem

Familial recurrent hydatidiform mole is a rare event; here we report an unusual case of a gravida 5 aged 29 years, with five recurrent hydatidiform moles and no normal pregnancy. After the fourth molar pregnancy, she developed persistent trophoblastic disease that required 7 cycles of single agent chemotherapy. Two years after the treatment, she presented with her fifth molar pregnancy. Her elder sister had seven hydatidiform moles from two different unrelated male partners. As this is familial, and recurrent, with no viable conceptions in both the sisters, it is likely to be biparental in origin. Unlike androgenetic moles, biparental moles arise due to a global inherited failure of maternal imprinting. It is an autosomal recessive defect in the female germ line. Genetic analysis is essential, although it is not available in all centers. Donor Oocyte IVF is the only option for women with biparental moles to have normal offspring.