Double trisomy in spontaneous miscarriages: cytogenetic and molecular approach

Numerical and structural chromosomal anomalies in first trimester products of conception

OBJECTIVE

Multiple or complex chromosomal abnormalities are rare and are correlated with advanced maternal age and spontaneous abortion early in pregnancy. This study investigates the frequency of complex chromosomal abnormalities in products of conception in the first trimester of pregnancy.

STUDY DESIGN

473 samples from first trimester aborted tissues were analyzed with conventional cytogenetic or molecular techniques. The average maternal age was 39 years (range 23-55). From each sample at least ten metaphases were analyzed using standard GTG banding.

RESULTS

From 351 fetal origin cultured samples diagnosis was possible at 339 (97 %). Abnormal karyotypes were detected in 216 embryos (64 %) and a normal karyotype was detected in 123 (36 %). Non-complex chromosomal abnormalities were detected in 192 cases (89 %) with single trisomy 16 being the most frequent and complex abnormalities were identified in 24 cases (11 %). Polyploidies and monosomy 45,X occurred in 8 % each. Structural rearrangements and mosaicism were detected in 2 % and 3 %, respectively. Statistical analysis showed association between the week of gestation of single and complex chromosomal abnormalities (p = 0.04136).

CONCLUSIONS

Our results confirm that embryos with complex chromosomal abnormalities were more frequent among older women (>39 years old) and were aborted one week earlier than embryos with non-complex chromosomal abnormalities. Additionally, we have identified a higher number of complex chromosomal abnormalities (11 % vs 5-7 % in literature). Among complex chromosomal abnormalities, double trisomy was the most common finding, and the most frequent chromosomes involved were 21, X, and 15.

The first reported case of double trisomy 10 and 20 in a product of conception

BACKGROUND

Double trisomies are rare findings among products of conception and are often lethal to the developing embryo or fetus.

METHODS

Here we describe a double trisomy case with symptoms of threatened miscarriage at 9 weeks gestation. Ultrasound revealed an anembryonic pregnancy. Pregnancy was terminated by dilation and curettage at gestational age 11 weeks and 6 days. Histologic examination and chromosome microarray were performed on a formalin-fixed product of conception (POC) sample to identify the cause of the anembryonic pregnancy.

RESULTS

Chromosome microarray analysis revealed a female chromosome complement with double trisomies 10 and 20, arr(10,20)x3, consistent with a karyotype of 48,XX,+10,+20.

CONCLUSION

To the best of our knowledge, this is the first reported case of double trisomy 10 and 20 in a POC. Due to nonspecific histopathological findings, chromosomal microarray is a powerful tool in identifying and differentiating chromosomal aneuploidies.

Double Trisomy 16 and 22 Clinically Mimic Partial Hydatidiform Mole in a Case of Subsequent Pregnancy Loss

A case of double trisomy 16 and 22 in the second pregnancy loss is presented. DNA analyses (short tandem repeats genotyping) of miscarriage specimen was indicated because of ultrasound suspicion of partial hydatidiform mole. After the partial hydatidiform mole exclusion, further DNA analyses focused on the most common aneuploidies causing pregnancy loss, detected double trisomy 16 and 22 in the product of conception. The couple was referred to clinical genetic consultation and normal parental karyotypes were proved. For further explanatory purposes, archived material from the first pregnancy loss was analyzed and trisomy of chromosome 18 was detected. By comparison of allelic profiles of the mother, father, and both losses, the maternal origin of all aneuploidies was proven what can be attributed to frequent meiosis errors, probably due to advanced maternal age (44 years at the first loss and 45 years at the second loss). In conclusion, aneuploidies can mimic partial hydatidiform mole. Genetic analysis is helpful on the one hand to rule out partial hydatidiform mole and on the other hand to identify aneuploidies and in this way to determine the cause of miscarriage.

Characteristics and mechanisms of mosaicism in prenatal diagnosis cases by application of SNP array

BACKGROUND

With the application of chromosome microarray, next-generation sequencing and other highly sensitive genetic techniques in disease diagnosis, the detection of mosaicism has become increasingly prevalent. This study involved a retrospective analysis of SNP array testing on 4512 prenatal diagnosis samples, wherein the characterization of mosaicism was explored and insights were gained into the underlying mechanisms thereof.

RESULTS

Using SNP array, a total of 44 cases of mosaicism were identified among 4512 prenatal diagnostic cases; resulting in a detection rate of approximately 1.0%. The prevalence of mosaicism was 4.1% for chorionic villus sample, 0.4% for amniotic fluid, and 1.3% for umbilical cord blood. Of these cases, 29 were mosaic aneuploidy and 15 were mosaic segmental duplication/deletion. Three cases of mosaic trisomy 16 and three cases of mosaic trisomy 22 were diagnosed in the CVS samples, while four cases of mosaic trisomy 21 were detected in amniotic fluid and umbilical cord blood samples. The distribution pattern of mosaicism suggested trisomy rescue as the underlying mechanism. Structurally rearranged chromosomes were observed, including three cases with supernumerary marker chromosomes, three cases with dicentric chromosomes, and one case with a ring chromosome. All mosaic segmental duplication/deletion cases were the result of mitotic non-disjunction, with the exception of one case involving mosaic11q segmental duplication.

CONCLUSION

Improved utilization of SNP arrays enables the characterization of mosaicism and facilitates the estimation of disease mechanisms and recurrence.

Double Aneuploidy of Down Syndrome (Trisomy 21) and Jacobs Syndrome (Trisomy XYY) with Complete Tracheal Rings Deformity: Case Report and Literature Review

Down syndrome (DS, trisomy 21) with an extra copy of chromosome 21 is one of the most common aneuploidies in humans. Jacobs syndrome or XYY syndrome (trisomy XYY) with an extra copy of sex chromosome Y is a rare sex chromosome trisomy in males. Double aneuploidy (DA) with an extra copy of chromosome 21 and sex chromosome Y is an extremely rare occurrence. Most trisomy 21 results from nondisjunction during maternal oocyte meiosis-I, whereas trisomy XYY is results from nondisjunction during paternal spermatocyte meiosis-I. We present a case of natural conception premature newborn of 30.4 weeks gestational age who had a DS facial phenotype with extensive syndactyly on both hands and feet. Other multisystem congenital anomalies were discovered, including mal-aligned perimembranous ventricular septal defect, bicuspid aortic valve, Dandy-Walker malformation's tetra-ventriculomegaly, and a rare complete tracheal rings deformity (CTRD) with trachea stenosis. Prenatal amniocentesis and postnatal chromosomal karyotyping analysis detected 48, XYY, + 21 nontranslocation trisomy 21, and free-lying Y chromosome without translocation. The existence of DA is rarely reported in literature reviews. In this review, we will discuss the characteristics of DS and Jacobs syndrome as well as the associated multiorgan malformation including the rare lethal CTRD.

First Croatian Case of Double Aneuploidy: A Child With Klinefelter and Edwards Syndrome (48,XXY,+18) - Possible Causes and Contributing Factors

We report a case of double aneuploidy in a preterm male newborn with karyotype 48,XXY,+18 whose mother was of advanced age and infected with the SARS-CoV-2 virus during the early stages of her pregnancy. The clinical features observed in the newborn included intrauterine growth retardation, dysmorphic facial features, overlapping fingers on both hands, respiratory distress syndrome, ventricular septal defect, patent ductus arteriosus, persistent pulmonary hypertension, and bilateral clubfoot, a phenotype that mainly correlates with Edwards syndrome (trisomy 18). To our knowledge, this is the first reported case of double aneuploidy in Croatia. This paper provides a detailed description of the clinical presentation and treatment strategies used, with the aim of providing valuable data for future recognition and management of similar cases. Furthermore, we discuss the mechanisms of nondisjunction that might account for this rare form of aneuploidy.

First prenatal case of Kagami-Ogata syndrome associated with a small supernumerary marker chromosome derived from chromosome 15

OBJECTIVE

Uniparental disomy (UPD) is one of the common causes of imprinting disorders, which can have an impact on gene expression according to the origin of the parental chromosome. Paternal UPD14 leads to Kagami-Ogata syndrome (KOS), which has a more severe phenotype than maternal UPD14, also called Temple syndrome. Small supernumerary marker chromosomes (SSMCs) are defined as structural chromosomal abnormalities that may be inherited or come from micronucleus-mediated chromothripsis. The association of UPD and SSMC is very rare but not fortuitous and several mechanisms can explain this phenomenon.

CASE REPORT

We report the first prenatal case of paternal isodisomy for chromosome 14 associated with a de novo SSMC originating from chromosome 15 and revealed by KOS. The mechanism could be a chromothripsis mediated by trisomy rescue.

CONCLUSION

Regarding this case, in relation to a de novo SSMC, it could be important to extend the research of UPD to other acrocentric chromosomes if ultrasound signs are evocative.

Copy number variation sequencing combined with quantitative fluorescence polymerase chain reaction in clinical application of pregnancy loss

PURPOSE

In this study, we evaluated the feasibility of the combining CNV-seq and quantitative fluorescence polymerase chain reaction (QF-PCR) for miscarriage analysis in clinical practice.

METHODS

Over a 35-month period, a total of 389 fetal specimens including 356 chorionic villi and 33 fetal muscle tissues were analyzed by CNV-seq and QF-PCR. Relationships between the risk factors (e.g., advanced maternal age, abnormal pregnancy history, and gestational age) and incidence of these chromosomal abnormalities were further analyzed by subgroup.

RESULTS

Clinically significant chromosomal abnormalities were identified in 58.95% cases. Aneuploidy was the most common abnormality (46.84%), followed by polyploidy (8.16%) and structural chromosome anomalies (3.95%). In sub-group analysis, significant differences were found in the total frequency of chromosomal abnormalities between the early abortion and the late abortion group, as well as in the distribution of chromosomal abnormalities between the advanced and the younger maternal age group. Meanwhile, the results of the logistic regression analysis identified a trend suggesting that the percentage of fetal chromosomal abnormalities is significantly higher in advanced maternal age, lesser gestational age, and lesser number of prior miscarriages.

CONCLUSION

Our study suggests that CNV-seq and QF-PCR are efficient and reliable technologies in the fetal chromosome analysis of miscarriages and could be used as a routine selection method for the genetic analysis of spontaneous abortion.

Application of Copy Number Variation Sequencing in Genetic Analysis of Miscarriages in Early and Middle Pregnancy

High-throughput sequencing based on copy number variation (CNV-seq) is commonly used to detect chromosomal abnormalities. This study identifies chromosomal abnormalities in aborted embryos/fetuses in early and middle pregnancy and explores the application value of CNV-seq in determining the causes of pregnancy termination. High-throughput sequencing was used to detect chromosome copy number variations (CNVs) in 116 aborted embryos in early and middle pregnancy. The detection data were compared with the Database of Genomic Variants (DGV), the Database of Chromosomal Imbalance and Phenotype in Humans using Ensemble Resources (DECIPHER), and the Online Mendelian Inheritance in Man (OMIM) database to determine the CNV type and the clinical significance. High-throughput sequencing results were successfully obtained in 109 out of 116 specimens, with a detection success rate of 93.97%. In brief, there were 64 cases with abnormal chromosome numbers and 23 cases with CNVs, in which 10 were pathogenic mutations and 13 were variants of uncertain significance. An abnormal chromosome number is the most important reason for embryo termination in early and middle pregnancy, followed by pathogenic chromosome CNVs. CNV-seq can quickly and accurately detect chromosome abnormalities and identify microdeletion and microduplication CNVs that cannot be detected by conventional chromosome analysis, which is convenient and efficient for genetic etiology diagnosis in miscarriage.

A child with complementary mosaic trisomy 8 and mosaic trisomy 21; clinical description of Warkany-Down syndrome and mechanism of origin

Aneuploidy mosaicism involving two complementary different autosomal trisomy cell lines is extremely rare. Although a mosaic double trisomy 8/trisomy 21 has been described in literature, this is the first report of Warkany (+8)-Down (+21) syndrome due to two complementary mosaic trisomy cell lines. The phenotype of the male patient with Warkany-Down syndrome includes upslanting palpebral fissures, hypertelorism, small low-set ears with unilateral aural stenosis, large and broad hands and feet with deep palmar and plantar creases, bilateral cryptorchidism, generalized mild hypotonia and transient neonatal thrombocytopenia. At the age of two years, his developmental quotient is around 50. His height, weight and head circumference are below the third centile. We speculate on the mechanism of origin of the complementary trisomy cell lines based on molecular cytogenetic studies that showed no evidence for a chimera.

Placental Histomorphology in a Case of Double Trisomy 48,XXX,+18

Background

Approximately 50% of early spontaneous abortions are found to have chromosomal abnormalities. In these cases, certain histopathologic abnormalities are suggestive of, although not diagnostic for, the presence of chromosomal abnormalities. However, placental histomorphology in cases of complex chromosomal abnormalities, including double trisomies, is virtually unknown.

Case Report

We present the case of a 27-year-old G3P22002 female presenting at 19 weeks and 1 day of gestation by last menstrual period for scheduled prenatal visit. Ultrasound revealed a single fetus without heart tones and adequate amniotic fluid. Limited fetal measurements were consistent with estimated gestational age of 17 weeks. Labor was induced with misoprostol due to fetal demise. Autopsy revealed an immature female fetus with grade 1-2 maceration. The ears were low-set and posteriorly rotated. The fingers were short bilaterally, and the right foot showed absence of the second and third digits. Evaluation of the organs showed predominantly marked autolysis consistent with retained stillbirth. Placental examination revealed multiple findings, including focal pseudovillous papilliform trophoblastic proliferation of the undersurface of the chorionic plate and clustering of perpendicularly oriented sclerotic chorionic villi in the chorion laeve, which have not been previously reported in cases of chromosomal abnormalities. Karyotype of placental tissue revealed a 48,XXX,+18 karyotype and the same double trisomy of fetal thymic tissue by FISH.

Conclusion

In addition to convoluted outlines of chorionic villi, villous trophoblastic pseudoinclusions, and clusters of villous cytotrophoblasts, the previously unreported focal pseudovillous papilliform trophoblastic proliferation of the undersurface of the chorionic plate and clustering of perpendicularly oriented sclerotic chorionic villi in the chorion laeve were observed in this double trisomy case. More cases have to be examined to show if the histology is specific for this double trisomy.

Exploring the cause of early miscarriage with SNP-array analysis and karyotyping

OBJECTIVE

The aim of this study is to explore the cause of miscarriage, providing risk assessment to guide the next pregnancy.

METHODS

Four hundred eighty-four products-of-conception (POC) samples were analyzed by single nucleotide polymorphism (SNP) array, and peripheral blood samples of couples were collected for karyotyping or fluorescence in situ hybridization (FISH) analysis.

RESULTS

Four hundred sixty-eight of the 484 (96.7%) fresh POC samples were successfully analyzed using SNP-array. The rate of clinically significant chromosomal abnormalities were 58.3% (274/468), in which rates of aneuploidy, polyploidy, partial aneuploidy, uniparental isodisomy (isoUPD), and pathogenic microdeletion/microduplication were 43.4% (203/468), 8.8% (41/468), 3.6% (17/468), 1.9% (9/48), and 0.9% (4/468), respectively. The percentage of embryonic chromosomal abnormalities significantly increased with maternal age of patients older than 35 years old. Among 468 couples, 12 major chromosomal rearrangements were detected by G-banding, including nine reciprocal translocations, two Robertsonian translocations, and one superfemale.

CONCLUSIONS

Chromosome abnormality is the main causes of early miscarriage, and aneuploidies are the most common type of chromosomal abnormalities. Application of SNP array and karyotyping in early miscarriage can provide more genetic information about miscarriage, providing risk assessment to guide the next pregnancy.

Double Aneuploidy Detected by Cell-Free DNA Testing and Confirmed by Fetal Tissue Analysis

BACKGROUND

Double aneuploidies account for 0.21-2.8% of spontaneous abortions resulting from chromosomal abnormalities. Rarely, cell-free DNA testing detects multiple aneuploidies; however, to discern among maternal, placental, and fetal origin, further evaluation is required.

CASE

A 49-year-old woman, gravida 5 para 0, underwent cell-free DNA testing at 11 4/7 weeks of gestation, which revealed a fetus that was high risk for trisomies 18 and 21. On ultrasonography at 14 weeks of gestation, she was diagnosed with a missed abortion and underwent surgical management. Fetal and placental tissues were sent for analysis and were positive for trisomies 18 and 21, confirming the results of cell-free DNA testing.

CONCLUSION

Our case highlights the ability of cell-free DNA testing to recognize a double aneuploidy confirmed by fetal tissue analysis.

Chromosomal anomalies in early spontaneous abortions: interphase FISH analysis on 855 FFPE first trimester abortions

OBJECTIVE

Cytogenetic analysis of spontaneous abortuses presents at least two main challenges, cell culture failure, and excess of normal female karyotypes related to maternal cell contamination (MCC). Molecular cytogenetic techniques using uncultured cell suspension overcome cell culture failure, but do not resolve MCC at all. The aim of the present study is to demonstrate that interphase fluorescence in situ hybridization (FISH) on routine formalin-fixed paraffin embedded (FFPE) abortive materials is an efficient method to identify chromosomal anomalies in abortuses and to detect MCC.

METHOD

Interphase FISH with a panel of eight probes was applied on 855 FFPE consecutive early spontaneous abortions.

RESULTS

Male/female ratio was 0.88 in the complete sample, 0.9 in the group of negative FISH result, and 0.8 in the group with abnormal FISH results, suggesting that no gender predominance was present in our data. The aneuploidy rate was 50.3%. Autosomal trisomies were 60%, polyploidies 23.2%, and X monosomy 14%. Chromosomal mosaicism was discovered in 1.9% with six cases of confined placental mosaicism.

CONCLUSION

FISH on FFPE abortion materials appears to be a successful approach to detect chromosomal anomalies in abortions. Moreover, the preservation of the tissue morphology allows the analysis of only the fetal cells, making the presence of maternal tissues irrelevant.

Report of a new case with pentasomy X and novel clinical findings

Pentasomy X is an extremely rare sex chromosome abnormality, a condition that only affects females, in which three more X chromosomes are added to the normally present two chromosomes in females. We investigated the novel clinical findings in a 1-year-old female baby with pentasomy X, and determined the parental origins of the X chromosomes. Our case had thenar atrophy, postnatal growth deficiency, developmental delay, mongoloid slant, microcephaly, ear anomalies, micrognathia and congenital heart disease. A conventional cytogenetic technique was applied for the diagnosis of the polysomy X, and quantitative fluorescent polymerase chain reaction (QF-PCR) using 11 inherited short tandem repeat (STR) alleles specific to the chromosome X for the determination of parental origin of X chromosomes. A cytogenetic evaluation revealed that the karyotype of the infant was 49,XXXXX. Comparison of the infant's features with previously reported cases indicated a clinically recognizable specific pattern of malformations referred to as the pentasomy X syndrome. However, to the best of our know-ledge, this is the first report of thenar atrophy in a patient with 49,XXXXX. The molecular analysis suggested that four X chromosomes of the infant originated from the mother as a result of the non disjunction events in meiosis I and meiosis II. We here state that the clinical manifestations seen in our case were consistent with those described previously in patients with pentasomy X. The degree of early hypotonia constitutes an important early prognostic feature in this syndrome. The pathogenesis of pentasomy X is not clear at present, but it is thought to be caused by successive maternal non disjunctions.

Cell-free DNA testing in a trisomy 21 pregnancy with confined placental mosaicism for a cell line with trisomy for both chromosomes 18 and 21

NIPT (noninvasive prenatal testing) detected trisomy for two chromosomes. One trisomy reflected the fetal karyotype, and the other resulted from CPM (confined placental mosaicism). This case illustrates that extensive cytogenetic analysis can be required to identify CPM, and that patients should be counseled regarding the possibility of discordant NIPT results.

Positive predictive value of non-invasive prenatal screening for fetal chromosome disorders using cell-free DNA in maternal serum: independent clinical experience of a tertiary referral center

BACKGROUND

Non-invasive prenatal screening (NIPS) for fetal chromosome abnormalities using cell-free deoxyribonucleic acid (cfDNA) in maternal serum has significantly influenced prenatal diagnosis of fetal aneuploidies since becoming clinically available in the fall of 2011. High sensitivity and specificity have been reported in multiple publications, nearly all of which have been sponsored by the commercial performing laboratories. Once results are returned, positive and negative predictive values (PPVs, NPVs) are the performance metrics most relevant to clinical management. The purpose of this report is to present independent data on the PPVs of NIPS in actual clinical practice.

METHODS

Charts were retrospectively reviewed for patients who had NIPS and were seen March 2012 to December 2013 in a tertiary academic referral center. NIPS results were compared to diagnostic genetic test results, fetal ultrasound results, and clinical phenotype/outcomes. The PPV was calculated using standard epidemiological methods. Correlation between screen results and both maternal age at delivery and gestational age at time of screening was assessed using Wilcoxon's rank sum test.

RESULTS

Of 632 patients undergoing NIPS, 92 % of tests were performed in one of the four major commercial laboratories offering testing. However, all four laboratories are represented in both the normal and abnormal results groups. There were 55 abnormal NIPS results. Forty-one of 55 abnormal NIPS results were concordant with abnormal fetal outcomes, 12 were discordant, and 2 were undetermined. The PPV for all conditions included in the screen was 77.4 % (95 % CI, 63.4 - 87.3). Of 578 patients with normal NIPS results, normal pregnancy outcome was confirmed for 156 (27 %) patients. This incomplete follow-up of normal NIPS results does not affect PPV calculations, but it did preclude calculations of sensitivity, specificity, and NPV. Maternal age at delivery was significantly lower for patients with abnormal discordant results, compared to patients with abnormal concordant results (P = 0.034). Gestational age at time of screening was not associated with concordance of screen results (P = 0.722).

CONCLUSIONS

The experience of using NIPS in clinical practice confirms that abnormal results cannot be considered diagnostic. Pre-test counseling should emphasize this. Diagnostic genetic testing should always be offered following abnormal NIPS results.

Phenotypic modifications of patients with full chromosome aneuploidies and concurrent suspected or confirmed second diagnoses

The coexistence of two or more distinct genetic conditions is known to be a rare phenomenon. Full chromosome aneuploidies can be associated with a broad variety of cytogenetic abnormalities or single gene disorders resulting in phenotypic modifications that confuse the diagnostic process. We present six patients with primary aneuploidies and a suspected or confirmed secondary genetic diagnosis or unusual birth defect. Among the cases included, we report the first patients with concurrent Down syndrome in combination with Prader-Willi, Craniofacial Microsomia, and Stickler syndromes. We also describe only the second reported case of a neonate with Down syndrome and Marfan syndrome. In all cases, the unusual clinical presentations lead to further molecular cytogenetic studies as well as single or multi-gene molecular evaluations. We make emphasis on the importance of entertaining the possibility of coexistent diagnoses when the phenotype is not what is expected for aneuploidies rather than attributing the unusual findings to rare or unreported associations of the primary aneuploidy.

Double trisomy 48,XXX,+18 with multiple dysmorphic features

BACKGROUND

Chromosomal abnormality is a common cause of congenital anomalies, psychiatric disorders, and mental retardation. However, the double trisomy 48,XXX,+18 is a rare chromosome abnormality.

METHODS

Case report and literature review.

RESULTS

A 7-hour-old girl presented to our unit because of poor response after birth. She presented with multiple dysmorphic features, including small for gestational age infant, flat nasal bridge, widely-spaced eyes, the left thumb deformities, flat facial profile, raised sternum, ventricular septal defect, the third lateral brain ventricle enlargement, and small liver. This case expands the spectrum of malformations reported in association with the double trisomy 48,XXX,+18. The literature on 16 fetuses or infants with the 48,XXX,+18 were also reviewed.

CONCLUSION

These data suggested that in patients with clinical features similar to trisomy 18, especially with anomalies of the ears and/or reproductive malformations, double trisomy (48,XXX,+18) should be considered and karyotyping should be performed although it is a rare disease.

Functional consequences of copy number variants in miscarriage

Background

The presence of unique copy number variations (CNVs) in miscarriages suggests that their integral genes have a role in maintaining early pregnancy. In our previous work, we identified 19 unique CNVs in ~40% of studied euploid miscarriages, which were predominantly familial in origin. In our current work, we assessed their relevance to miscarriage by expression analysis of 14 genes integral to CNVs in available miscarriage chorionic villi. As familial CNVs could cause miscarriage due to imprinting effect, we investigated the allelic expression of one of the genes (TIMP2) previously suggested to be maternally expressed in placenta and involved in placental remodelling and embryo development.

Results

Six out of fourteen genes had detectable expression in villi and for three genes the RNA and protein expression was altered due to maternal CNVs. These genes were integral to duplication on Xp22.2 (TRAPPC2 and OFD1) or disrupted by a duplication mapping to 17q25.3 (TIMP2). RNA and protein expression was increased for TRAPPC2 and OFD1 and reduced for TIMP2 in carrier miscarriages. The three genes have roles in processes important for pregnancy development such as extracellular matrix homeostasis (TIMP2 and TRAPPC2) and cilia function (OFD1). TIMP2 allelic expression was not affected by the CNV in miscarriages in comparison to control elective terminations.

Conclusion

We propose that functional studies of CNVs could help determine if and how the miscarriage CNVs affect the expression of integral genes. In case of parental CNVs, assessment of the function of their integral genes in parental reproductive tissues should be also considered in the future, especially if they affect processes relevant for pregnancy development and support.

Electronic supplementary material

The online version of this article (doi:10.1186/s13039-015-0109-8) contains supplementary material, which is available to authorized users.

Double and multiple chromosomal aneuploidies in spontaneous abortions: A single institutional experience

OBJECTIVE:

To characterize double and multiple aneuploidies in spontaneous abortions (SAB).

MATERIALS AND METHODS:

Retrospective analysis of cytogenetics data obtained by culturing/harvesting products of the conception material at our center from 2006 to 2009 was performed. The abnormal cytogenetic results, maternal age, gestational age, and previous pregnancy history were recorded and compared.

RESULTS:

Double and multiple aneuploidies are rare, however, a high percentage of double (4.6%) and multiple (0.4%) chromosomal aneuploidies were observed in our study of 1502 cases of SAB. Of 1502 cases of SAB evaluated, 70 cases (4.6%) showed double aneuploidy, whereas 6 cases (0.4%) had multiple aneuploidies. The chromosomes most frequently involved in double aneuploidy in the decreasing order were 21, 16, ± X, 22, 18, 13, and 15. The most frequent chromosome combinations observed were: Loss of X/21 (8.5%), 21/22 (4.4%), 16/21 (4.4%), and 7/16 (4.4%). The chromosome combinations in multiple aneuploidy included trisomy of chromosomes X/5/8, 8/20/22, 16/20/22, 14/21/22, and loss of X with 21/21 and 7/21. These abnormalities were significantly observed in women between the age group 40-44 years (59.2%). A high success rate (94%) of obtaining metaphase cells was observed in this study mainly due to the use of direct and long-term cultures.

CONCLUSIONS:

We observed a high percentage of double (4.6%) and multiple (0.4%) aneuploidies, frequently involving the acrocentic chromosomes 13, 15, 21, and 22 and nonacrocentric chromosomes X, 16, and 18.

Prenatal diagnosis of chromosomal mosaicism in over 1600 cases using array comparative genomic hybridization as a first line test

OBJECTIVE

The aim of this study was to assess the detection of chromosomal mosaicism in chorionic villus (CVS) and amniotic fluid (AF) samples using array comparative genomic hybridization (aCGH) and quantitative fluorescent polymerase chain reaction.

METHODS

All patients undergoing invasive prenatal testing by aCGH at a specialist prenatal screening service were included in the study. A total of 1609 samples (953 CVS and 656 AF) underwent quantitative fluorescent polymerase chain reaction and targeted aCGH without concurrent conventional G-banded karyotyping.

RESULTS

Chromosomal mosaicism was detected in 20 of the 1609 cases (1.24%); of which 17 were derived from 953 CVS (1.78%), and three from 656 AF (0.46%). Mosaicism was observed at a level as low as 9%. Four cases were likely confined placental mosaicism, 12 were likely true fetal mosaicism, and four cases were unable to be classified into either group.

CONCLUSIONS

This study demonstrates that the use of aCGH as a first line test is able to identify chromosomal mosaicism down to 9%, which is lower than the level reliably detected using standard cytogenetic analysis. aCGH avoids the disadvantages of culturing, which include culture bias, artifact, and culture failure.

Rapid detection of fetal aneuploidies by quantitative fluorescent-polymerase chain reaction for prenatal diagnosis in the Turkish population

Prenatal diagnosis is testing for diseases or conditions in a fetus or embryo before it is born. It employs a variety of techniques to determine the health and condition of an unborn fetus. The main goal of this process is to perform prenatal diagnosis at the earliest possible stage of gestation. In this regard, quantitative fluorescent-polymerase chain reaction (QF-PCR), a novel technique that is fast and reliable, was employed to detect aneuploidies (13, 18, 21, X and Y) without the need of the time-consuming culturing process. The QF-PCR method can detect five different chromosome aneuploidies with 98.6% accuracy. In this study, 1874 amniotic fluid samples of pregnant subjects, who were referred to the Department of Medical Biology and Genetics, Adana, Turkey (molecular biology section), were analyzed with the QF-PCR technique by employing 27 short tandem repeat (STR) markers to detect chromosomes 13, 18, 21, X and Y aneuploidies. We detected 31 subjects (1.7%) with aneuploidies or euploidies out of the 1874 subjects. The average age of the pregnant subjects was 32 (range: 14-49). Abnormal karyotypes detected were as follows: 47,XX,+21 (19.4%, 6/31), 47,XY,+21 (48.4%, 15/31), 48,XXX,+21 (3.2%, 1/31), 69,XXX (3.2%, 1/31), 47,XY,+13 (3.2%, 1/31), 47,XXY (9.6%, 3/31), 47,XXX (9.6%, 3/31) and 45,X (3.2%, 1/31). Moreover, some STR markers were found to be more specific to the Turkish population. In conclusion, QF-PCR can be regarded as an alternative method of conventional cytogenetic analysis as it is a rapid and reliable method; however, in most cases it is required to be supported or validated with conventional cytogenetic karyotyping and some STR markers employed for QF-PCR can be more informative for a given population.

Rapid detection of aneuploidy and unbalanced chromosomal rearrangements by subtelomeric multiplex ligation-dependent probe amplification in fetuses with congenital heart disease

OBJECTIVE

To validate multiplex ligation-dependent probe amplification (MLPA) with subtelomeric probe mixes as a tool for diagnosis of aneuploidy and unbalanced terminal chromosomal rearrangements in fetuses with congenital heart disease.

METHODS

A prospective study of 117 fetuses found to have structural heart defects by ultrasound at 17-40 weeks' gestation. MLPA with P036E and P070B probe mixes was performed and compared to traditional karyotyping by cell culture and to findings of quantitative fluorescence-polymerase chain reaction (QF-PCR).

RESULTS

MLPA was able to define the fetal karyotype in 99% of cases whereas cell culture only defined the karyotype in 64% of cases. Consequently, the overall number of chromosomal abnormalities that were detected increased. The majority of these affected chromosomes, 21, 18, 13, X or Y, were also confirmed by QF-PCR. Two (5%) cases had atypical aneuploidy that was confirmed by MLPA but not by QF-PCR. In 4 cases, structural rearrangements or mosaicism were not detected by MLPA.

CONCLUSIONS

Subtelomeric MLPA may be a valuable adjunct to QF-PCR and/or conventional cytogenetics for the investigation of chromosomal abnormalities in fetuses with congenital heart disease.

Double aneuploidy with Edwards-Klinefelter syndromes (48,XXY,+18) of maternal origin: prenatal diagnosis and molecular cytogenetic characterization in a fetus with arthrogryposis of the left wrist and aplasia of the left thumb

OBJECTIVE

To present the prenatal diagnosis and molecular investigation of the parental origin and mechanism of nondisjunction underlying an 48,XXY,+18 karyotype in a fetus with congenital abnormalities, and to review the literature.

MATERIALS, METHODS, AND RESULTS

A 42-year-old woman was referred for amniocentesis at 18 weeks of gestation because of advanced maternal age. Prenatal ultrasound revealed bilateral choroid plexus cysts. Amniocentesis revealed a karyotype of 48,XXY,+18. The parental karyotypes were normal. Level II ultrasound revealed a flexion contracture deformity of the left wrist with absence of the thumb. The pregnancy was terminated at 22 weeks of gestation. A 332 g male fetus was delivered with clenched hands, arthrogryposis of the left wrist, aplasia of the left thumb, micrognathia, low-set ears, hypertelorism, rocker-bottom feet, and a normal penis. Quantitative fluorescent polymerase chain reaction assays using polymorphic DNA markers showed a triallelic pattern with a dosage ratio of 1:1:1 (paternal:maternal:maternal) for chromosome 18-specific markers, and a monoallelic pattern of a single maternal allele for chromosome X-specific markers. The fetus inherited two copies of two different maternal alleles on chromosome 18, and two copies of a single maternal allele on chromosome X. The molecular result, along with the karyotype of 48,XXY,+18, was consistent with the occurrence of nondisjunction of chromosome 18 in a maternal meiosis I error and nondisjunction of chromosome X in a maternal meiosis II error or less likely a postzygotic mitotic error.

CONCLUSION

The present case provides evidence that abnormal separation of chromosomes 18 and X resulting in double aneuploidy may occur in different cell divisions, and such an occurrence is related to advanced maternal age.

A small supernumerary marker chromosome, derived from chromosome 22, possibly associated with repeated spontaneous abortions

We report a phenotypically normal couple with repeated spontaneous abortions and without other clinical features. Clinical, hematological, biochemical, and endocrinological aspects of the couple did not reveal any abnormalities. The karyotype of the wife was normal (46,XX), while the husband was found to have an abnormal karyotype, 47,XY,+der(22)mat. The marker chromosome was familial and non-satellite. Although the potential risk of small supernumerary marker chromosomes for spontaneous abortions cannot be defined precisely, marker chromosomes, together with methods used for ascertainment, are also factors to be considered when investigating infertility consequences. Furthermore, identification of the origin of a marker chromosome may provide additional information for patient karyotype-phenotype correlations. Further studies, such as molecular analyses to identify the breakpoint, are necessary for investigating phenotype-genotype correlations and assessment of genetic risks for small secondary chromosomes. The cause of repeated spontaneous abortions in this couple might be the presence of this marker chromosome in the husband. Consequently, we recommended genetic counseling before further pregnancies.

Mechanisms of mosaicism, chimerism and uniparental disomy identified by single nucleotide polymorphism array analysis

Mosaic aneuploidy and uniparental disomy (UPD) arise from mitotic or meiotic events. There are differences between these mechanisms in terms of (i) impact on embryonic development; (ii) co-occurrence of mosaic trisomy and UPD and (iii) potential recurrence risks. We used a genome-wide single nucleotide polymorphism (SNP) array to study patients with chromosome aneuploidy mosaicism, UPD and one individual with XX/XY chimerism to gain insight into the developmental mechanism and timing of these events. Sixteen cases of mosaic aneuploidy originated mitotically, and these included four rare trisomies and all of the monosomies, consistent with the influence of selective factors. Five trisomies arose meiotically, and three of the five had UPD in the disomic cells, confirming increased risk for UPD in the case of meiotic non-disjunction. Evidence for the meiotic origin of aneuploidy and UPD was seen in the patterns of recombination visible during analysis with 1-3 crossovers per chromosome. The mechanisms of formation of the UPD included trisomy rescue, with and without concomitant trisomy, monosomy rescue, and mitotic formation of a mosaic segmental UPD. UPD was also identified in an XX/XY chimeric individual, with one cell line having complete maternal UPD consistent with a parthenogenetic origin. Utilization of SNP arrays allows simultaneous evaluation of genomic alterations and insights into aneuploidy and UPD mechanisms. Differentiation of mitotic and meiotic origins for aneuploidy and UPD supports existence of selective factors against full trisomy of some chromosomes in the early embryo and provides data for estimation of recurrence and disease mechanisms.

Parental Origin and Cell Stage Errors in X-Chromosome Polysomy 49, XXXXY

Polysomy 49, XXXXY is a rare sex chromosome aneuploidy syndrome characterized by mental retardation, severe speech impairment, craniofacial abnormalities, multiple skeletal defects and genital abnormalities. We describe a patient with 49, XXXXY syndrome who had many characteristics of Fraccaro syndrome; language impairment, mongoloid slant, epicanthal folds, cryptorchidism, umbilical hernia and dysmyelinization in his brain. A GTG-banding technique was used for karyotype analysis of peripheral blood cell cultures. The parental origin of polysomy X was identified by using quantitative fluorescent polymerase chain reaction (QF-PCR) with seven short tandem repeat (STR) markers specific for the X/Y-chromosome which revealed that all the X-chromosomes were of maternal origin. This report provides evidence for successive non disjunctions in maternal meiosis I and II.

Causes of Fetal Wastage

Fetal wastage has many causes, but genetic factors are by far the most common. The earlier the pregnancy loss occurs, the greater the likelihood of genetic causation. Among first trimester abortions, 50% to 80% show chromosomal abnormalities, usually aneuploidy. This is greater than all other causes combined. Chromosomal numerical abnormalities can be recurrent and sporadic; failure to take this into account is a major pitfall in many reports addressing causation. Moreover, many causes of fetal wastage that are traditionally considered to be "nongenetic" are actually the result of perturbations of gene products-proteins. Among nongenetic causes of first trimester fetal wastage, the best established are thyroid abnormities; antifetal antibodies; and the inherited and acquired thrombophilias. The latter are more established in the second trimester. Uterine anomalies can lead to second trimester losses. Infections seem uncommon, and alloimmune causes are not validated.

MLPA as a screening method of aneuploidy and unbalanced chromosomal rearrangements in spontaneous miscarriages

OBJECTIVE

The present study aims to validate multiplex ligation-dependent probe amplification (MLPA) technique with subtelomeric probe mixes as a screening method to detect aneuploidy and unbalanced terminal chromosomal rearrangements in spontaneous abortions (SAs).

METHODS

MLPA with P036B and P070 probe mixes was performed on 221 miscarriage DNA samples between the 5th and 24th week of gestation. Cytogenetic culture was attempted on 178 miscarriages. Karyotyped miscarriages served as controls in this blinded study. Results were confirmed by quantitative fluorescent-PCR (QF-PCR).

RESULTS

Among the karyotyped miscarriages, MLPA was able to detect all the expected aneuploidies, as well as an unbalanced product from a reciprocal translocation, and revealed cryptic deletions and duplications not visible at the 550-band resolution level. In addition, chromosomal anomalies were found in approximately 37% of cases that failed to grow or could not be cultivated. As expected, ploidy changes were not detected. Copy number variation was found for target sequences of P036B (CYFIP1, MRPL41, CAB45) and P070 (DECR2, TNFRSF18) probe mixes.

CONCLUSIONS

We propose the use of MLPA with subtelomeric probe mixes as a reliable, rapid and economical first approach to detect aneuploidy and unbalanced terminal chromosomal rearrangements in SAs.