Invasive procedures for prenatal diagnosis: Any future left?

Single-cell whole-genome sequencing, haplotype analysis in prenatal diagnosis of monogenic diseases

Monogenic inherited diseases are common causes of congenital disabilities, leading to severe economic and mental burdens on affected families. In our previous study, we demonstrated the validity of cell-based noninvasive prenatal testing (cbNIPT) in prenatal diagnosis by single-cell targeted sequencing. The present research further explored the feasibility of single-cell whole-genome sequencing (WGS) and haplotype analysis of various monogenic diseases with cbNIPT. Four families were recruited: one with inherited deafness, one with hemophilia, one with large vestibular aqueduct syndrome (LVAS), and one with no disease. Circulating trophoblast cells (cTBs) were obtained from maternal blood and analyzed by single-cell 15X WGS. Haplotype analysis showed that CFC178 (deafness family), CFC616 (hemophilia family), and CFC111 (LVAS family) inherited haplotypes from paternal and/or maternal pathogenic loci. Amniotic fluid or fetal villi samples from the deafness and hemophilia families confirmed these results. WGS performed better than targeted sequencing in genome coverage, allele dropout (ADO), and false-positive (FP) ratios. Our findings suggest that cbNIPT by WGS and haplotype analysis have great potential for use in prenatally diagnosing various monogenic diseases.

Nanostructures in non-invasive prenatal genetic screening

Prenatal screening is an important issue during pregnancy to ensure fetal and maternal health, as well as preventing the birth of a defective fetus and further problems such as extra costs for the family and society. The methods for the screening have progressed to non-invasive approaches over the recent years. Limitations of common standard screening tests, including invasive sampling, high risk of abortion and a big delay in result preparation have led to the introduction of new rapid and non-invasive approaches for screening. Non-invasive prenatal screening includes a wide range of procedures, including fetal cell-free DNA analysis, proteome, RNAs and other fetal biomarkers in maternal serum. These biomarkers require less invasive sampling than usual methods such as chorionic villus sampling, amniocentesis or cordocentesis. Advanced strategies including the development of nanobiosensors and the use of special nanoparticles have provided optimization and development of NIPS tests, which leads to more accurate, specific and sensitive screening tests, rapid and more reliable results and low cost, as well. This review discusses the specifications and limitations of current non-invasive prenatal screening tests and introduces a novel collection of detection methods reported studies on nanoparticles' aided detection. It can open a new prospect for further studies and effective investigations in prenatal screening field.

The effect of maternal body mass index and gestational age on circulating trophoblast yield in cell-based noninvasive prenatal testing

OBJECTIVE

To examine the effects of maternal body mass index (BMI) and gestational age (GA) on the number of single circulating trophoblasts (SCT).

METHODS

Maternal blood was collected in 20 to 40 mL. All singleton pregnant women at any gestation were recruited. Trophoblasts were recovered by immunomagnetic enrichment and stained for cytokeratin and CD45. Candidate trophoblasts were identified by fluorescence microscopy.

RESULTS

Blood samples were collected from 425 singleton pregnancies from April 2018 to December 2019. At least one candidate cell was identified in 88% (373/425). There was an inverse correlation between trophoblasts yield and increasing BMI (r = -0.19, P < .001). The mean ± SD number of trophoblasts/mL was 0.12  ± 0.22 in the underweight group (n = 5), 0.23 ± 0.25 in the normal weight (n = 169), 0.18 ± 0.19 in the overweight (n = 114), and 0.13 ± 0.15 in the obese (n = 109). Significantly more cells were identified in the normal weight than those in the obese (P = .001). In addition, the mean ± SD number of cells/mL was 0.21  ± 0.21 at GA of 10 to 14 weeks (n = 260), 0.14 ± 0.23 at GA ≥15 (n = 102) and 0.12 ± 0.12 at GA <10 (n = 63); P < .001.

CONCLUSION

The lower number of SCT was identified from the samples of women with a high BMI. Cell recovery for SCT testing seems optimal at GA of 10 to 14 weeks, but earlier and later testing is still possible.

Antenatally detected liver and biliary pathology

Liver and biliary pathology in the neonate are rare and include a broad range of structural, neoplastic, infectious, genetic, and metabolic diseases. While most conditions present postnatally, antenatal detection is increasing given recent advances in antenatal imaging capabilities. In certain structural or obstructive liver diseases, antenatal detection now proves essential to help guide treatment and prevent morbidity. We review the epidemiology, pathophysiology, common antenatal diagnostic findings, and recommendations for surgical liver and biliary pathology in the neonate.

Genome-wide non-invasive prenatal testing in single- and multiple-pregnancies at any risk: Identification of maternal polymorphisms to reduce the number of unnecessary invasive confirmation testing

OBJECTIVE

Non-invasive prenatal testing by targeted or genome-wide copy number profiling (cnNIPT) has the potential to outperform standard NIPT targeting the common trisomies 13, 18, and 21, only. Nevertheless, prospective results and outcome data on cnNIPT are still scarce and there is increasing evidence for maternal copy number variants (CNVs) interfering with results of both, standard and cnNIPT.

STUDY DESIGN

We assessed the performance of cnNIPT in 3053 prospective and 116 retrospective cases with special consideration of maternal CNVs in singleton and multiple gestational pregnancies at any risk, as well as comprehensive follow-up.

RESULTS

A result was achieved in 2998 (98.2%) of total prospective cases (89.2% analyzed genome-wide). Confirmed fetal chromosomal abnormalities were detected in 45 (1.5%) cases, of which five (11%) would have remained undetected in standard NIPTs. Additionally, we observed 4 likely fetal trisomies without follow-up and a likely phenotype associated placental partial trisomy 16. Moreover, we observed clinically relevant confirmed maternal CNVs in 9 (0.3%) cases and likely maternal clonal hematopoiesis in 3 (0.1%). For common fetal trisomies we prospectively observed a very high sensitivity (100% [95% CI: 91.96-100%]) and specificity (>99.9% [95% CI: 99.8-100%]), and positive predictive value (PPV) (97.8% [95% CI: 86.1-99.7%]), but our retrospective control cases demonstrated that due to cases of fetal restricted mosaicism the true sensitivity of NIPT is lower. After showing that 97.3% of small CNVs prospectively observed in 8.3% of genome-wide tests were mostly benign maternal variants, sensitivity (75.0% [95% CI: 19.4%-99.4%]), specificity (99.7% [99.5%-99.9%]) and PPV (30.0% [14.5%-52.1%]) for relevant fetal CNVs were relatively high, too. Maternal autoimmune disorders and medication, such as dalteparin, seem to impair assay quality.

CONCLUSION

When maternal CNVs are recognized as such, cnNIPT showed a very high sensitivity, specificity and PPV for common trisomies in single and multiple pregnancies at any risk and very good values genome-wide. We found that the resolution for segmental aberrations is generally comparable to standard karyotyping, and exceeds the latter if the fetal fraction is above 10%, which allows detection of the 2.5 Mb 22q11.2 microdeletion associated with the velocardiofacial syndrome, even if the mother is not a carrier.

Highly sensitive and rapid isolation of fetal nucleated red blood cells with microbead-based selective sedimentation for non-invasive prenatal diagnostics

Non-invasive prenatal diagnostics (NIPD) has been an emerging field for prenatal diagnosis research. Carrying the whole genome coding of the fetus, fetal nucleated red blood cells (FNRBCs) have been pursued as a surrogate biomarker traveling around in maternal blood. Here, by combining a unique microbead-based centrifugal separation and enzymatic release, we demonstrated a novel method for FNRBC isolation from the blood samples. First, the gelatin-coated silica microbeads were modified with FNRBC-specific antibody (anti-CD147) to capture the target cells in the blood samples. Then, the density difference between microbead-bound FNRBCs and normal blood cells enables the purification of FNRBCs via an improved high-density percoll-based separation. The non-invasive release of FNRBCs can then be achieved by enzymatically degrading the gelatin film on the surface of the microbeads, allowing a gentle release of the captured target cells with as high as 84% efficiency and ∼80% purity. We further applied it to isolate fetal cells from maternal peripheral blood. The released cells were analyzed by real-time polymerase chain reaction to verify their fetal origin and fluorescent in situ hybridization to detect fetal chromosome disorders. This straightforward and reliable alternative platform for FNRBC detection may have the potential for realizing facile NIPD.

Frequency-enhanced transferrin receptor antibody-labelled microfluidic chip (FETAL-Chip) enables efficient enrichment of circulating nucleated red blood cells for non-invasive prenatal diagnosis

Fetal aneuploidy and other chromosomal aberrations affect 9 in 1000 live births. Unlike the invasive diagnosis with high risk of miscarriage, non-invasive prenatal diagnosis (NIPD) sampling from maternal blood becomes a promising way for fetal genetic screening. However, fetal cell-based NIPD has a major challenge due to the small number of fetal cells present in maternal blood. We designed a frequency-enhanced transferrin receptor antibody-labelled microfluidic chip (FETAL-Chip) for efficient enrichment and identification of circulating fetal cells, i.e., circulating nucleated red blood cells (cNRBCs) from maternal blood. The FETAL-Chip can dramatically enhance the interaction of fetal cells with antibody-coated microposts to increase the capture efficiency while minimizing nonspecific adsorption. With the help of immunostaining, we can identify cNRBCs from as little as 2 milliliter maternal blood. Various numbers of cNRBCs were detected from volunteers as early as 7 weeks after conception and throughout the entire pregnancy. Gene analysis was also carried out to confirm the fetal origin of captured cells. With easy, non-invasive and highly efficient enrichment of cNRBCs, the method presented here offers great potential for non-invasive prenatal diagnosis.

The SEeMORE strategy: single-tube electrophoresis analysis-based genotyping to detect monogenic diseases rapidly and effectively from conception until birth

BACKGROUND

The development of technologies that detect monogenic diseases in embryonic and fetal samples are opening novel diagnostic possibilities for preimplantation genetic diagnosis (PGD) and prenatal diagnosis (PND) thereby changing laboratory practice. Molecular diagnostic laboratories use different workflows for PND depending on the disease, type of biological sample, the presence of one or more known mutations, and the availability of the proband. Paternity verification and contamination analysis are also performed. The aim of this study was to test the efficacy of a single workflow designed to optimize the molecular diagnosis of monogenic disease in families at-risk of transmitting a genetic alteration.

METHODS

We used this strategy, which we designated "SEeMORE strategy" (Single-tube Electrophoresis analysis-based genotyping to detect MOnogenic diseases Rapidly and Effectively from conception to birth). It consists of a multiplex PCR that simultaneously carries out linkage analysis, direct analysis, maternal contamination and parenthood testing. We analyzed samples from previously diagnosed families for PND (cystic fibrosis or Duchenne muscular dystrophy) without, however, knowing the results.

RESULTS

The results obtained with the SEeMORE strategy concurred with those obtained with traditional PND. In addition, this strategy has several advantages: (i) use of one or a few cells; (ii) reduction of the procedure to 1 day; and (iii) a reduction of at least 2-3-fold of the analytic cost.

CONCLUSIONS

The SEeMORE strategy is effective for the molecular diagnosis of monogenic diseases, irrespective of the amount of starting material and of the disease mutation, and can be used for PND and PGD.

Obstetric professionals' perceptions of non-invasive prenatal testing for Down syndrome: clinical usefulness compared with existing tests and ethical implications

BACKGROUND

While non-invasive prenatal testing (NIPT) for fetal aneuploidy is commercially available in many countries, little is known about how obstetric professionals in non-Western populations perceive the clinical usefulness of NIPT in comparison with existing first-trimester combined screening (FTS) for Down syndrome (DS) or invasive prenatal diagnosis (IPD), or perceptions of their ethical concerns arising from the use of NIPT.

METHODS

A cross-sectional survey among 327 obstetric professionals (237 midwives, 90 obstetricians) in Hong Kong.

RESULTS

Compared to FTS, NIPT was believed to: provide more psychological benefits and enable earlier consideration of termination of pregnancy. Compared to IPD, NIPT was believed to: provide less psychological stress for high-risk women and more psychological assurance for low-risk women, and offer an advantage to detect chromosomal abnormalities earlier. Significant differences in perceived clinical usefulness were found by profession and healthcare sector: (1) obstetricians reported more certain views towards the usefulness of NIPT than midwives and (2) professionals in the public sector perceived less usefulness of NIPT than the private sector. Beliefs about earlier detection of DS using NIPT were associated with ethical concerns about increasing abortion. Participants believing that NIPT provided psychological assurance among low-risk women were less likely to be concerned about ethical issues relating to informed decision-making and pre-test consultation for NIPT.

CONCLUSIONS

Our findings suggest the need for political debate initially on how to ensure pregnant women accessing public services are informed about commercially available more advanced technology, but also on the potential implementation of NIPT within public services to improve access and equity to DS screening services.

Interventions et techniques de diagnostic prénatal visant l'obtention d'un prélèvement fœtal à des fins diagnostiques : Risques et avantages pour la mère et le fœtus

OBJECTIF

Offrir aux fournisseurs de soins de maternité et à leurs patientes des lignes directrices factuelles contemporaines en ce qui concerne les services de counseling traitant des risques et des avantages maternels propres à la tenue des interventions diagnostiques prénatales orientées par échographie (et/ou des techniques permettant l'établissement d'un diagnostic génétique) nécessaires dans les cas où il a été établi pendant la période prénatale que la grossesse serait exposée à des risques, ainsi qu'en ce qui concerne la prise de décisions subséquentes quant à la prise en charge de la grossesse (questions abordant des aspects tels que le niveau du fournisseur de soins obstétricaux, la surveillance prénatale, le lieu où devraient se dérouler les soins et l'accouchement, et la décision de poursuivre ou d'interrompre la grossesse). La présente directive clinique se limite aux services de counseling traitant des risques et des avantages maternels, et aux décisions en matière de prise en charge de la grossesse pour les femmes qui nécessitent (ou qui envisagent) la mise en œuvre d'une intervention ou d'une technique effractive orientée par échographie aux fins de l'établissement d'un diagnostic prénatal.

POPULATION DE PATIENTES

Femmes enceintes identifiées, à la suite de la mise en œuvre de protocoles établis de dépistage prénatal (taux sériques maternels ± imagerie, résultats d'analyse de l'ADN acellulaire indiquant des risques élevés, résultats anormaux au moment de l'imagerie fœtale diagnostique ou antécédents familiaux de troubles héréditaires), comme étant exposées à un risque accru d'anomalie génétique fœtale. Ces femmes pourraient nécessiter ou demander des services de counseling au sujet des risques et des avantages pour la grossesse de la tenue d'une intervention effractive orientée par échographie visant à déterminer l'étiologie, le diagnostic, et/ou la pathologie de possibles anomalies fœtales. RéSULTATS: La littérature publiée a été récupérée par l'intermédiaire de recherches menées dans Medline, PubMed et The Cochrane Library jusqu'en juin 2014 au moyen d'un vocabulaire contrôlé (« prenatal diagnosis », « amniocentesis », « chorionic villi sampling », « cordocentesis ») et de mots clés (« prenatal screening », « prenatal genetic counselling », « post-procedural pregnancy loss rate ») appropriés. Les résultats ont été restreints aux analyses systématiques, aux études observationnelles et aux essais comparatifs randomisés / essais cliniques comparatifs publiés en anglais entre janvier 1985 et juin 2014. Les recherches ont été mises à jour de façon régulière et intégrées à la directive clinique jusqu'en juin 2014. La littérature grise (non publiée) a été identifiée par l'intermédiaire de recherches menées dans les sites Web d'organismes s'intéressant à l'évaluation des technologies dans le domaine de la santé et d'organismes connexes, dans des collections de directives cliniques, dans des registres d'essais cliniques et auprès de sociétés de spécialité médicale nationales et internationales.

VALEURS

La qualité des résultats a été évaluée au moyen des critères décrits dans le rapport du Groupe d'étude canadien sur les soins de santé préventifs (Tableau 1). AVANTAGES, DéSAVANTAGES ET COûTS: Consentement éclairé de la patiente, transfert des connaissances, évaluation du risque génétique prénatal, soulagement de l'anxiété, création d'anxiété, défense des droits, compréhension du dépistage fœtal, limites du dépistage fœtal, choix en matière de prise en charge de la grossesse, complication de la grossesse ou fausse couche, soins opportuns et améliorés pour l'accouchement d'un enfant présentant une morbidité reconnue. RECOMMANDATIONS.

Fetal nucleated red blood cell analysis for non-invasive prenatal diagnostics using a nanostructure microchip

Cell-free DNA has been widely used in non-invasive prenatal diagnostics (NIPD) nowadays. Compared to these incomplete and multi-source DNA fragments, fetal nucleated red blood cells (fNRBCs), once as an aided biomarker to monitor potential fetal pathological conditions, have re-attracted research interest in NIPD because of their definite fetal source and the total genetic information contained in the nuclei. Isolating these fetal cells from maternal peripheral blood and subsequent cell-based bio-analysis make maximal genetic diagnosis possible, while causing minimal harm to the fetus or its mother. In this paper, an affinity microchip is reported which uses hydroxyapatite/chitosan nanoparticles as well as immuno-agent anti-CD147 to effectively isolate fNRBCs from maternal peripheral blood, and on-chip biomedical analysis was demonstrated as a proof of concept for NIPD based on fNRBCs. Tens of fNRBCs can be isolated from 1 mL of peripheral blood (almost 25 mL^-1 in average) from normal pregnant women (from the 10th to 30th gestational week). The diagnostic application of fNRBCs for fetal chromosome disorders (Trisomy 13 and 21) was also demonstrated. Our method offers effective isolation and accurate analysis of fNRBCs to implement comprehensive NIPD and to enhance insights into fetal cell development.

Invasive prenatal diagnosis of fetal thalassemia

Thalassemia is the most common monogenic inherited disease worldwide, affecting individuals originating from many countries to various extents. As the disease requires long-term care, prevention of the homozygous state presents a substantial global disease burden. The comprehensively preventive programs involve carrier detections, molecular diagnostics, genetic counseling, and prenatal diagnosis. Invasive prenatal diagnosis refers to obtaining fetal material by chorionic villus sampling (CVS) at the first trimester, and by amniocentesis or cordocentesis at the second trimester. Molecular diagnosis, which includes multiple techniques that are aimed at the detection of mutations in the α- or β-globin genes, facilitates prenatal diagnosis and definitive diagnosis of the fetus. These are valuable procedures for couples at risk, so that they can be offered options to have healthy offspring. According to local practices and legislation, genetic counseling should accompany the invasive diagnostic procedures, DNA testing, and disclosure of the results. The most critical issue in any type of prenatal molecular testing is maternal cell contamination (MCC), especially when a fetus is found to inherit a particular mutation from the mother. The best practice is to perform MCC studies on all prenatal samples. The recent successful studies of fetal DNA in maternal plasma may allow future prenatal testing that is non-invasive for the fetus and result in significant reduction of invasive diagnostic procedures.

Experiences of Prenatal Genetic Screening and Diagnostic Testing Among Pregnant Korean Women of Advanced Maternal Age

PURPOSE

This study explored the experiences of Korean women of advanced maternal age undergoing prenatal genetic screening and diagnostic testing.

DESIGN

A descriptive, qualitative design was used to guide the study.

METHOD

Ten participants were purposely recruited from a large metropolitan Korean hospital for clinical observations and individual, semistructured interviews. The content analysis method was used to analyze field notes and interview transcripts.

FINDINGS

Three themes emerged: reacting to an unfavorable screening result, dealing with the anticipated consequences of diagnostic testing, and realistically embracing the unborn child.

CONCLUSIONS

The findings of this study inform the development of tailored interventions aimed at reducing the heavy emotional burdens placed on pregnant women and the stigma of bearing children with genetic conditions. Clear reciprocal communication and shared decision making should be promoted in the day-to-day practice of delivering health care for pregnant Korean women.

Knowledge and Attitudes Regarding Non-Invasive Prenatal Testing (NIPT) and Preferences for Risk Information among High School Students in Sweden

Non-invasive prenatal testing (NIPT) was recently introduced for prenatal testing of genetic disorders. Cell-free fetal DNA is present in maternal blood during pregnancy and enables detection of fetal chromosome aberrations in a maternal blood sample. The public perspective to this new, simple method has not been illuminated. The views of young people (i.e. future parents) are important to develop suitable counseling strategies regarding prenatal testing. The aim was to explore Swedish high school students’ attitudes, knowledge and preferences regarding NIPT. A questionnaire was completed by 305 students recruited from one high school in Stockholm, November and December 2014. Most students (80 %) considered prenatal testing as good. The majority (65 %) was positive or very positive towards NIPT and 62 % stated that they potentially would like to undergo the test if they or their partner was pregnant. The vast majority (94 %) requested further information about NIPT. Most students (61 %) preferred verbal information, whereas 20 % preferred information via the Internet. The majority of the high school students was positive towards prenatal testing and most was positive towards NIPT. Further, information was requested by the vast majority before making a decision about NIPT. Most of the students preferred verbal information and to a lesser extent information via the Internet. The attitudes, knowledge and preferences for risk information concerning NIPT in young adults are important, in order to increase knowledge on how to educate and inform future parents.

Positive Attitudes towards Non-Invasive Prenatal Testing (NIPT) in a Swedish Cohort of 1,003 Pregnant Women

Objective

The clinical utilization of non-invasive prenatal testing (NIPT) for identification of fetal aneuploidies is expanding worldwide. The aim of this study was to gain an increased understanding of pregnant women’s awareness, attitudes, preferences for risk information and decision-making concerning prenatal examinations with emphasis on NIPT, before its introduction into Swedish healthcare.

Method

Pregnant women were recruited to fill in a questionnaire, including multiple-choice questions and Likert scales, at nine maternity clinics located in different areas of Stockholm, Sweden.

Results

In total, 1,003 women participated in the study (86% consent rate). The vast majority (90.7%) considered examinations aiming to detect fetal abnormalities to be good. Regarding NIPT, 59.8% stated that they had heard about the method previously, yet 74.0% would like to use the test if available. The main factor affecting the women’s decision to undergo prenatal chromosomal screening was worry about the baby’s health (82.5%), followed by the urge to have as much information as possible about the fetus (54.5%). Most women (79.9%) preferred to receive NIPT information orally.

Conclusion

The overwhelming majority of a cohort of 1,003 pregnant women considered prenatal examinations good. Moreover, the majority had a positive attitude towards NIPT and would like to use the test if available.

About one-half of early spontaneous preterm deliveries can be identified by a rapid matrix metalloproteinase-8 (MMP-8) bedside test at the time of mid-trimester genetic amniocentesis

OBJECTIVE

Mid-trimester amniocentesis continues to be used for the prenatal diagnosis of chromosomal anomalies and other genetic disorders. Analysis of amniotic fluid obtained at the time of mid-trimester genetic amniocentesis identifies those patients who are at risk for early spontaneous preterm delivery. This is based on a solid body of evidence that found subclinical intra-amniotic inflammation/infection to be causally linked to early spontaneous preterm birth. Although several biomarkers have been proposed to identify intra-amniotic inflammation, the accumulated data suggest that the determination of amniotic fluid matrix metalloproteinase-8 (MMP-8), or neutrophil collagenase, is a powerful predictor of spontaneous preterm delivery. MMP-8 is released by inflammatory cells in response to microbial products or "danger signals". A rapid point-of-care test has been developed to determine MMP-8 at the bedside within 20 min, and without the requirement of laboratory equipment. The objective of this study was to determine whether an elevation of MMP-8 in the amniotic fluid, measured by a rapid point-of-care test, can identify those patients at risk for spontaneous preterm delivery after a mid-trimester genetic amniocentesis.

STUDY DESIGN

A case-control study was designed to obtain amniotic fluid from asymptomatic singleton pregnant women who underwent mid-trimester genetic amniocentesis. An MMP-8 bedside test was performed to analyze the amniotic fluid of 64 patients with early spontaneous preterm delivery (<30 weeks) and 128 matched controls with normal pregnancy outcomes.

RESULTS

(1) The MMP-8 bedside test (Yoon's MMP-8 Check™) was positive in 42.2% (27/64) of patients with spontaneous preterm delivery but in none (0/128) of the control cases (p < 0.001); (2) the MMP-8 bedside test had a sensitivity of 42.2%, and a specificity of 100% in the prediction of spontaneous preterm delivery (<30 weeks) following a mid-trimester genetic amniocentesis; and (3) among the patients with spontaneous preterm delivery, those with a positive MMP-8 bedside test had a significantly higher rate of spontaneous delivery within 2 weeks and 4 weeks of an amniocentesis [40.7% (11/27) versus 5.4% (2/37); 63.0% (17/27) versus 24.3% (9/37)] and a shorter interval-to-delivery period than those with a negative test [interval-to-delivery: median (range), 16 d (0-95 d) versus 42 d (2-91 d); p < 0.05 for each].

CONCLUSION

We conclude that 42% of patients with an early spontaneous preterm delivery (< 30 weeks) could be identified by a rapid MMP-8 bedside test at the time of their mid-trimester genetic amniocentesis. The MMP-8 bedside test is a powerful predictor of early spontaneous preterm birth in asymptomatic pregnant women.

Changes in and Efficacies of Indications for Invasive Prenatal Diagnosis of Cytogenomic Abnormalities: 13 Years of Experience in a Single Center

Background

Because the future application of cell-free fetal DNA screening is expected to dramatically improve the diagnostic yield and reduce unnecessary invasive procedures, it is time to summarize the indications of invasive prenatal diagnosis. This retrospective study was performed to evaluate the changes and efficacies of indications of invasive procedures for detecting cytogenomic abnormalities from 2000 to 2012.

Material/Methods

From our regional obstetric unit, 7818 invasive procedures were referred by indications of advance maternal age (AMA), abnormal ultrasound findings (aUS), abnormal maternal serum screening (aMSS), and family history (FH). Chromosome, fluorescence in situ hybridization (FISH), and array comparative genomic hybridization (aCGH) analyses were performed on chorionic villus sampling (CVS) and amniotic fluid (AF) specimens at the Yale Cytogenetics Laboratory. The abnormal findings from single or combined indications were compared to evaluate the diagnostic yield.

Results

The annual caseload declined by 57.2% but the diagnostic yield increased from 7.2% to 13.4%. Chromosomal and genomic abnormalities were detected in 752 cases (9.6%, 752/7818) and 12 cases (4%, 12/303), respectively. Significantly decreased AMA referrals and increased aUS and aMSS referrals were noted. The top 3 indications by diagnostic yield were AMA/aUS (51.4% for CVS, 24.2% for AF), aUS (34.7% for CVS, 14.5% for AF), and AMA/aMSS (17.8% for CVS, 9.9% for AF).

Conclusions

Over a period of 13 years, the indication of aMSS and aUS were increasing while AMA was decreasing for prenatal diagnosis of cytogenomic abnormalities, and there was a continuous trend of reduced invasive procedures. Prenatal evaluation using AMA/aUS was the most effective in detecting chromosomal abnormalities, but better indications for genomic abnormalities are needed.

Utilization of noninvasive prenatal testing: impact on referrals for diagnostic testing

OBJECTIVE

Since the introduction of noninvasive prenatal testing (NIPT), a marked decrease in prenatal diagnostic testing (chorionic villus sampling [CVS] and amniocentesis) has been observed with unknown potential effects on genetic diagnosis of these pregnancies. The purpose of this study was to understand the impact of NIPT on genetics counseling referrals, diagnostic testing with CVS/amniocentesis, and appropriate use of NIPT.

STUDY DESIGN

A retrospective cohort study was performed on all women referred for genetic counseling and prenatal testing during the 2 years preceding the introduction of NIPT (pre-NIPT) and 2 years following (post-NIPT). The primary outcome was the difference in the number of women referred for genetic counseling and prenatal diagnosis during the pre-NIPT period compared with the post-NIPT period. The secondary outcome was the difference in the number of women referred who were not considered candidates for NIPT between the 2 study periods.

RESULTS

There was a statistically significant reduction in the number of referrals for genetic counseling and diagnostic testing in the post-NIPT compared with the pre-NIPT period (2824 vs 3944, P = .001), a reduction of 28.4%. During the post-NIPT period there was a significant reduction in referrals of women who would not be candidates for NIPT (467 pre-NIPT vs 285 post-NIPT, P = .043). In women who had diagnostic testing with CVS during the study period, 32.4% of the aneuploidies identified would not have been detected by NIPT.

CONCLUSION

There was a significant reduction in the number of patients referred for genetic counseling and prenatal diagnosis following the introduction of NIPT. In addition, there was a significant reduction in the number of patients referred for counseling and testing who would not be candidates for NIPT. This suggests that an increasing number of potential patients are being offered NIPT screening instead of diagnostic testing, including those at risk for fetal single gene disorders and aneuploidies not detectable by NIPT, potentially leading to misdiagnosis.

Impact of Cell-Free Fetal DNA Screening on Patients' Choice of Invasive Procedures after a Positive California Prenatal Screen Result

Until recently, maternal serum analyte levels paired with sonographic fetal nuchal translucency measurement was the most accurate prenatal screen available for Trisomies 18 and 21, (91% and 94% detection and false positive rates of 0.31% and 4.5% respectively). Women with positive California Prenatal Screening Program (CPSP) results have the option of diagnostic testing to determine definitively if the fetus has a chromosomal abnormality. Cell-free fetal (cff-) DNA screening for Trisomies 13, 18, and 21 was first offered in 2012, allowing women with positive screens to choose additional screening before diagnostic testing. Cff-DNA sensitivity rates are as high as 99.9% and 99.1%, with false positive rates of 0.4% and 0.1%, for Trisomies 18 and 21, respectively. A retrospective chart review was performed in 2012 on 500 CPSP referrals at the University of California, San Diego Thornton Hospital. Data were collected prior to and after the introduction of cff-DNA. There was a significant increase in the number of participants who chose to pursue additional testing and a decrease in the number of invasive procedures performed after cff-DNA screening was available. We conclude that as fetal aneuploidy screening improves, the number of invasive procedures will continue to decrease.

Pregnancy Loss Following Amniocentesis or CVS Sampling-Time for a Reassessment of Risk

Risk of procedure-related pregnancy loss is currently widely quoted in the UK as 1% for amniocentesis and 1.5% for chorionic villus sampling. Published data suggest that these risk figures are out of date and inaccurate, and that new guidelines are required for pre-test counseling. It is our opinion that accurate and evidence-based information concerning miscarriage risk is vital when counseling women, as exaggeration of this risk may deter women from testing, or cause unjustified remorse if a miscarriage ensues. It is also essential that health-care economists are aware of the up-to-date evidence on “procedure-related risk” when applying risk-benefit analysis to assess new technology for non-invasive screening.

Lab-on-a-chip technology: impacting non-invasive prenatal diagnostics (NIPD) through miniaturisation

This paper aims to provide a concise review of non-invasive prenatal diagnostics (NIPD) to the lab-on-a-chip and microfluidics community. Having a market of over one billion dollars to explore and a plethora of applications, NIPD requires greater attention from microfluidics researchers. In this review, a complete overview of conventional diagnostic procedures including invasive as well as non-invasive (fetal cells and cell-free fetal DNA) types are discussed. Special focus is given to reviewing the recent and past microfluidic approaches to NIPD, as well as various commercial entities in NIPD. This review concludes with future challenges and ethical considerations of the field.

A method for noninvasive detection of fetal large deletions/duplications by low coverage massively parallel sequencing

OBJECTIVE

To report the feasibility of fetal chromosomal deletion/duplication detection using a novel bioinformatic method of low coverage whole genome sequencing of maternal plasma.

METHOD

A practical method Fetal Copy-number Analysis through Maternal Plasma Sequencing (FCAPS), integrated with GC-bias correction, binary segmentation algorithm and dynamic threshold strategy, was developed to detect fetal chromosomal deletions/duplications of >10 Mb by low coverage whole genome sequencing (about 0.08-fold). The sensitivity/specificity of the resultant FCAPS algorithm in detecting deletions/duplications was firstly assessed in silico and then tested in 1311 maternal plasma samples from those with known G-banding karyotyping results of the fetus.

RESULTS

Deletions/duplications, ranged from 9.01 to 28.46 Mb, were suspected in four of the 1311 samples, of which three were consistent with the results of fetal karyotyping. In one case, the suspected abnormality was not confirmed by karyotyping, representing a false positive case. No false negative case was observed in the remaining 1307 low-risk samples. The sensitivity and specificity for detection of >10-Mb chromosomal deletions/duplications were100% and 99.92%, respectively.

CONCLUSION

Our study demonstrated FCAPS has the potential to detect fetal large deletions/duplications (>10 Mb) with low coverage maternal plasma DNA sequencing currently used for fetal aneuploidy detection.

The evolving role of genetics in reproductive medicine

As medicine has evolved over the last century, medical genetics has grown from nonexistence to one of the most visible aspects of how we understand and treat disease. This increased role of genetics within medicine will only increase in the coming years, and its role in reproductive medicine will be significant. Genetics has emerged as a primary focus of research with translational applications within reproductive medicine. The aim of this article is to outline the applications of genetics currently available, and how these technologies can provide a positive impact on patient care.

Chromosomal Microarrays in Prenatal Diagnosis: Time for a Change of Policy?

Microarrays have replaced conventional karyotyping as a first-tier test for unbalanced chromosome anomalies in postnatal cytogenetics mainly due to their unprecedented resolution facilitating the detection of submicroscopic copy number changes at a rate of 10-20% depending on indication for testing. A number of studies have addressed the performance of microarrays for chromosome analyses in high risk pregnancies due to abnormal ultrasound findings and reported an excess detection rate between 5% and 10%. In low risk pregnancies, clear pathogenic copy number changes at the submicroscopic level were encountered in 1% or less. Variants of unclear clinical significance, unsolicited findings, and copy number changes with variable phenotypic consequences are the main issues of concern in the prenatal setting posing difficult management questions. The benefit of microarray testing may be limited in pregnancies with only moderately increased risks (advanced maternal age, positive first trimester test). It is suggested to not change the current policy of microarray application in prenatal diagnosis until more data on the clinical significance of copy number changes are available.

Physician recommendation for invasive prenatal testing: the case of the 'precious baby'

STUDY QUESTION

Do clinicians manage pregnancies conceived by assisted reproductive technologies (ART) differently from spontaneous pregnancies?

SUMMARY ANSWER

Clinicians' decisions about prenatal testing during pregnancy depend, at least partially, on the method of conception.

WHAT IS KNOWN ALREADY

Research thus far has shown that patients' decisions regarding prenatal screening are different in ART pregnancies compared with spontaneous ones, such that ART pregnancies may be considered more valuable or 'precious' than pregnancies conceived without treatment.

STUDY DESIGN, SIZE AND DURATION

In this cross-sectional study, preformed during the year 2011, 163 obstetricians and gynecologists in Israel completed an anonymous online questionnaire.

PARTICIPANTS, SETTING, METHODS

Clinicians were randomly assigned to read one of two versions of a vignette describing the case of a pregnant woman. The two versions differed only with regard to the method of conception (ART; n = 78 versus spontaneous; n = 85). Clinicians were asked to provide their recommendations regarding amniocentesis.

MAIN RESULTS AND THE ROLE OF CHANCE

The response rate among all clinicians invited to complete the questionnaire was 16.7%. Of the 85 clinicians presented with the spontaneous pregnancy scenario, 37 (43.5%) recommended amniocentesis. In contrast, of the 78 clinicians presented with the ART pregnancy scenario, only 15 (19.2%) recommended the test. Clinicians were 3.2 (95% confidence interval [CI]: 1.6-6.6) times more likely to recommend amniocentesis for a spontaneous pregnancy than for an ART pregnancy.

LIMITATIONS AND REASONS FOR CAUTION

The study is limited by a low response rate, the relatively small sample and the hypothetical nature of the decision, as clinician recommendations may have differed in an actual clinical setting.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings show that fertility history and use of ART may affect clinicians' recommendations regarding amniocentesis following receipt of screening test results. This raises the question of how subjective factors influence clinicians' decisions regarding other aspects of pregnancy management.

STUDY FUNDING AND COMPETING INTEREST

There was no funding source to this study. The authors declare no conflicts of interest.

Prenatal diagnosis and 47,XXY

In this contribution, we consider detection of 47,XXY by a variety of available methods. These include traditional invasive procedures, screening with maternal serum analytes and fetal ultrasound, and most recently cell-free fetal DNA. Since its introduction in the late 1960s, prenatal genetic diagnosis has evolved greatly. Serendipitious detection of 47,XXY was not infrequent when prenatal genetic diagnosis routinely involved testing by the invasive procedures CVS and amniocentesis. In 2013 this is much less common and relatively few pregnancies in the U.S. and Europe are tested without prior screening protocols, traditionally maternal serum analyte and fetal ultrasound (NT). These protocols are not designed to identify 47,XXY or other X-chromosome aneuploides and with screening by analysis of cell-free DNA in maternal blood, this situation may or may not be altered. Increased numbers of cases could be detected if intake increases and vendors offer information on 47,XXY. A further consideration is that ability of array CGH to detect microdeletions or microduplications below resolution of a karyotype could make return to direct testing using an invasive procedure attractive.

Cell-free fetal DNA and maternal serum analytes for monitoring embryonic and fetal status

Biomarkers can be employed for screening for fetal genetic disorders, identifying individuals at sufficiently high risk for a confirmatory invasive procedure. In this article we discuss prenatal genetic aneuploidy screening. Maternal serum analytes and ultrasound have long been routinely offered, providing detection rates of 80% to 93% for trisomy 21; however, an invasive procedure (false-positive) must be performed in 5% of pregnancies screened. Recovering fetal cells from maternal blood initially proved inconsistent, but new methods recovering trophoblasts offer promise for detecting disorders using a single fetal cell, analogous to preimplantation genetic diagnosis. Current emphasis is focused predominantly on cell-free fetal DNA, which accounts for 5% to 10% of total cell-free DNA in maternal blood. Analysis of maternal blood results in detection rates of over 99% for fetal trisomy 21, and also very high rates for trisomy 18 and sex chromosomal abnormalities. Such detection rates are substantively higher than with maternal serum analytes, and are accompanied by a much lower (<1%) false-positive rate.

Noninvasive screening tools for Down syndrome: a review

Down syndrome is the leading cause of prenatal chromosome abnormalities, accounting for 53% of all reported chromosome conditions. Testing strategies, guidelines, and screening options have expanded from their conception in the 1970s, and now include such options as anatomical ultrasound, maternal serum screening, and noninvasive prenatal testing. This review summarizes all currently available noninvasive diagnostic techniques for the detection of Down syndrome. By understanding fully each technology and the possible alternatives, the physician will be able to provide their patients with all the information necessary to make an informed decision regarding their medical management.