P–553 Women with molar pregnancies have a genetic susceptibility to aneuploid miscarriages

Study question

What causes non-molar miscarriages in women with one hydatidiform mole (HM)?

Summary answer

We found a higher rate of aneuploidies in the non-molar miscarriages of women with HM than in those from women with sporadic or recurrent miscarriages.

What is known already

Women with hydatidiform moles have higher rates of miscarriages and women with recurrent miscarriages have higher rates of moles than women from the general population.

Study design, size, duration

We retrieved archived formalin-fixed paraffin embedded tissues from non-molar miscarriages of patients with one HM and analyzed them for the presence of aneuploidies using single nucleotide polymorphism (SNP)-microarray. We next determined the meiotic origin of the aneuploidies by genotyping the aneuploid non-molar miscarriages along with the parental genomes using microsatellite markers.

Participants/materials, setting, methods

All participants and some of their partners provided written consent to participate in our study, agreed to a blood draw for genotyping analysis, and agreed for us to retrieve their molar and non-molar tissues from various histopathology laboratories for research purposes.

Main results and the role of chance

We demonstrate for the first time that patients with an HM and miscarriages are at higher risk for aneuploid miscarriages [83.3%, 95% confidence interval (CI): 0.653–0.944] than women with sporadic (51.5%, 95% CI: 50.3–52.7%, p value = 0.0003828) or recurrent miscarriages (43.8%, 95% CI: 40.7–47.0%, p value = 0.00002). Genotyping the aneuploid miscarriages and the parental genomes demonstrated that most of the aneuploidies originated from errors in maternal meiosis I or II.

Limitations, reasons for caution

We were able to retrieve only 30 non-molar miscarriages from women with one HM for analysis. Expanding such analysis to a larger and independent cohort of miscarriages from such patients will be important to validate our observations.

Wider implications of the findings: Our data suggest common genetic female germline defects predisposing to HM and aneuploid non-molar miscarriages in some patients.

Trial registration number

Not applicable

Recurrent triploid and dispermic conceptions in patients with NLRP7 mutations

To understand the mechanisms leading to hydatidiform mole formation in patients with NLRP7 mutations, we used a combination of various approaches to characterize five products of conception, from two patients, shown by flow cytometry to contain non-diploid cells. We demonstrate that four of these conceptions are triploid and two of them originated from fertilization with more than one sperm. We show that three of these triploid conceptions fulfill the histopathological criteria of partial hydatidiform mole and one fulfills the histopathological criteria of spontaneous abortion. Our data demonstrate that some oocytes from one patient with NLRP7 mutations are not able to prevent polyspermic fertilization and highlight the importance of using several approaches to characterize the genetic complexity of molar tissues and reproductive wastage. Altogether, our previous and current data show the association of NLRP7 mutations with several types of hydatidiform moles and with triploid spontaneous abortions.

Cytogenetic and histologic correlation of peripheral nerve sheath tumors of soft tissue

Cytogenetic analysis was performed on 11 peripheral nerve sheath tumors of soft tissue from 10 patients. They include 6 benign and 5 malignant schwannomas. Five cases which include two benign, one cellular and two malignant schwannomas had a known association with a nerve, but only one patient with malignant schwannoma has clinically documented neurofibromatosis type I. All the patients had a normal diploid constitutional karyotype. Two cases of cellular schwannoma were analyzed by routine cytogenetic analysis and fluorescence in situ hybridization (FISH). One tumor was karyotyped as 45, XX,-13,-22 +mar; and the other case had a 45,X,-Y,t(1;17) (p12;q11.2) karyotype. In the latter, the breakpoint in 17q occurred below the centromere and is at or in the region of the Neurofibromatosis Type 1 (NF1) gene. Four benign tumors had a normal diploid karyotype. One hypodiploid malignant schwannoma with myxoid features demonstrated monosomy of chromosomes 17 and 22 by FISH analysis. The rest of the malignant schwannomas showed a wide range of numerical and structural aberrations, with frequent loss of 22q and gains of chromosomes 2 and 7. Loss of a sex chromosome was observed in cellular as well as malignant schwannomas. Regional karyotypic evolution was noted in one malignant schwannoma. Cytogenetic analysis may prove to be useful in identifying tumors, such as cellular schwannomas, which, because of their histologic features may be inadvertently categorized as malignant. Simultaneous involvement of NF1 and NF2 genes, which are located on chromosomes 17q and 22q, respectively, should be investigated at a molecular level in both benign and malignant tumors of peripheral nerves.

Cytogenetics and origins of pediatric germ cell tumors

We present cytogenetic and DNA fingerprint analysis on 13 new cases of pediatric germ cell tumors; we analyze further four cases we have reported previously. The patients ranged in age from 23 weeks gestation to 16 years. The tumors were located in the ovary, sacrococcygeum, testis, mediastinum, and the craniofacial region, and represented benign, immature, and malignant cases. All of the new cases had a normal diploid karyotype. We have previously reported on multiple genetic mechanisms of origin for ovarian germ cell tumors, namely meiosis I nondisjunction, meiosis II nondisjunction, endoreduplication of a haploid ovum, mitotic division of premeiotic germ cell, and fusion of two ova. To determine the origin of extragonadal and testicular GCTs, Q-band centromeric heteromorphisms and DNA markers were analyzed in the host and the cognate tumor. Our data suggest that extragonadal and testicular GCTs do not arise by a meiosis I or II error, or by endoreduplication; rather, they arise mitotically from either a somatic or a germ cell.

Genetics and biology of human ovarian teratomas. III. Cytogenetics and origins of malignant ovarian germ cell tumors

This report presents cytogenetic data on three cases of malignant ovarian germ cell tumors. All were diagnosed as malignant teratoma; case 1 with yolk sac elements; case 2 with elements of endodermal sinus tumor, embryonal carcinoma, and choriocarcinoma; and case 3 with yolk sac elements and embryonal carcinoma. Metaphase cells from each tumor, and normal tissue from the host, were karyotyped and scored for centromeric heteromorphisms in an attempt to determine the mechanism of origin. The karyotypes were 79,XXX,+1,+3,-6,+8,+12,+14,-15,+17, +20,+21,+22;49,XX,+8,+12,+22; and 48,XX,+3,+14, respectively. The analysis of centromeric heteromorphisms and DNA fingerprints of host and teratoma using the M13 probe revealed that one case originated from a germ cell before the first meiotic division. Normal host tissue was not available in case 2, but several centromeric markers were heterozygous in the tumor, indicating either meiosis I error or complete failure of germ cell meiosis. In the third case the centromeric heteromorphisms that were heterozygous in the host appeared to be homozygous for certain chromosomes and heterozygous for others in the tumor. These results suggest that germ cell teratomas could arise by the fusion of two ova.

Squamous cell carcinoma in situ arising in an ovarian mature cystic teratoma. Report of one case with histopathologic, cytogenetic, and flow cytometric DNA content analysis

A squamous cell carcinoma in situ arose in an ovarian mature teratoma (ie, dermoid cyst) in a 62-year-old woman. Flow cytometric DNA content analysis of paraffin-embedded in situ carcinoma showed a normal DNA content with moderate to high proliferative activity (S-phase fraction estimate, 16% to 18%). Cytogenetic analysis of the in situ cancer and the benign cystic portion of the tumor revealed a 46,XX karyotype. In addition, the benign cystic portion of the tumor revealed homozygous chromosomal heteromorphisms, compared with heterozygous markers found in peripheral blood lymphocytes. These results show that this squamous cell carcinoma in situ was euploid and suggest that the mature cystic teratoma was derived from a single germ cell after meiosis I.

Genetics and biology of human ovarian teratomas. I. Cytogenetic analysis and mechanism of origin

One hundred and two benign, mature ovarian teratomas and two immature, malignant teratomas were karyotyped and scored for centromeric heteromorphisms as part of an ongoing project to determine the chromosomal karyotype and the genetic origin of ovarian teratomas and to assess their utility for gene-centromere mapping. Karyotypic analysis of the benign cases revealed 95 46,XX teratomas and 7 chromosomally abnormal teratomas (47,XXX, 47,XX,+8 [two cases], 47,XX,+15, 48,XX,+7,+12 91,XXXX,-13 [mosaic], 47,XX,-15,+21,+mar). Our study reports on the first cases of tetraploidy and structural rearrangement in benign ovarian teratomas. The two immature cases had modal chromosome numbers of 78 and 49. Centromeric heteromorphisms that were heterozygous in the host were homozygous in 65.2% (n = 58) of the benign teratomas and heterozygous in the remaining 34.8% (n = 31). Chromosome 13 heteromorphisms were the most informative, with 72.7% heterozygosity in hosts. The cytogenetic data indicate that 65% of teratomas are derived from a single germ cell after meiosis I and failure of meiosis II (type II) or endoreduplication of a mature ovum (type III); 35% arise by failure of meiosis I (type I) or mitotic division of premeiotic germ cells (type IV).