Non-invasive Prenatal Testing: Technologies, Clinical Assays and Implementation Strategies for Women's Healthcare Practitioners

α- and β-Genotyping of Thalassemia Patients Based on a Multimodal Liver MRI Radiomics Model: A Preliminary Study in Two Centers

BACKGROUND

So far, there is no non-invasive method that can popularize the genetic testing of thalassemia (TM) patients on a large scale. The purpose of the study was to investigate the value of predicting the α- and β- genotypes of TM patients based on a liver MRI radiomics model.

METHODS

Radiomics features of liver MRI image data and clinical data of 175 TM patients were extracted using Analysis Kinetics (AK) software. The radiomics model with optimal predictive performance was combined with the clinical model to construct a joint model. The predictive performance of the model was evaluated in terms of AUC, accuracy, sensitivity, and specificity.

RESULTS

The T2 model showed the best predictive performance: the AUC, accuracy, sensitivity, and specificity of the validation group were 0.88, 0.865, 0.875, and 0.833, respectively. The joint model constructed from T2 image features and clinical features showed higher predictive performance: the AUC, accuracy, sensitivity, and specificity of the validation group were 0.91, 0.846, 0.9, and 0.667, respectively.

CONCLUSION

The liver MRI radiomics model is feasible and reliable for predicting α- and β-genotypes in TM patients.

A new and improved method of library preparation for non-invasive prenatal testing: plasma to library express technology

OBJECTIVES

This study aims to develop a novel library preparation method, plasma to library express technology (PLET), to construct next-generation sequencing (NGS) libraries directly from plasma without cell-free DNA (cfDNA) isolation.

METHODS

Peripheral blood samples (600) were obtained from a retrospective cohort of 300 pregnant women prior to invasive diagnostic testing. The samples were subsequently distributed between library preparation methodologies, with 300 samples prepared by PLET and 300 by conventional methods for non-invasive prenatal testing (NIPT) to screen for common trisomies using low-pass whole genome next generation sequencing.

RESULTS

NIPT conducted on PLET libraries demonstrated comparable metrics to libraries prepared using conventional methods, including 100% sensitivity and specificity.

CONCLUSIONS

Our study demonstrates the potential utility of PLET in the clinical setting and highlights its significant advantages, including dramatically reduced process complexity and markedly decreased turnaround time.

Noninvasive prenatal testing of beta-thalassemia for common Pakistani mutations: a comparative study using cell-free fetal DNA from maternal plasma and chorionic villus sampling

BACKGROUND

The discovery of circulating cell-free fetal DNA (cff-DNA) in maternal plasma has inspired the noninvasive prenatal testing (NIPT) approaches for various genetic fetal screening including rhesus D typing, sex determination, aneuploidies, and single-gene disorders.

OBJECTIVE

Noninvasive determination of paternally inherited beta-thalassemia mutations in maternal total cell-free DNA (cf-DNA) by using allele-specific amplification refractory mutation system (ARMS) real-time PCR (RT-PCR) in concordance with the conventional invasive method.

METHODS

An observational study was conducted at the Armed Forces Institute of Blood Transfusion in collaboration with the genetics resource center from March 2021 to August 2021. A total number of 26 couples were selected having a history of previously affected children with beta-thalassemia. A routine chorionic villus sampling (CVS) invasive procedure was carried out, and the mutation analysis was done using conventional PCR. To assess NIPT, a total cf-DNA was also extracted from maternal plasma and analyzed using allele-specific ARMS RT-PCR.

RESULTS

Based on conventional PCR testing, 13 of 26 couples were found having beta-thalassemia carriers with homozygous mutation, and 13 couples were carriers with heterozygous mutations. Further to assess NIPT, the cf-DNA of 13 pregnant females among the couples with different mutational patterns was analyzed by allele-specific ARMS RT-PCR to detect paternally inherited mutations. In comparison with conventional PCR, 11 cases (84.6%) were matched successfully, while two cases (15.4%) had no concordance with conventional invasive prenatal testing (IPT).

CONCLUSION

NIPT using maternal cf-DNA by allele-specific ARMS RT-PCR can be feasible to screen paternal inherited mutant alleles to rule out pregnant women from invasive procedures where the test would be negative for paternal inheritance. However, a low amount of fetal DNA in maternal plasma is a limiting factor and required further improvement to enrich fetal cf-DNA for complete concordance with conventional IPT.

Evaluation of the clinical performance of noninvasive prenatal testing at a Japanese laboratory

AIM

We aimed to evaluate the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of noninvasive prenatal testing (NIPT) in high-risk pregnant women.

METHODS

Pregnant women who underwent GeneTech NIPT, the most commonly used NIPT in Japan, between January 2015 and March 2019, at Japan NIPT Consortium medical sites were recruited for this study. The exclusion criteria were as follows: pregnant women with missing survey items, multiple pregnancy/vanishing twins, chromosomal abnormalities in the fetus other than the NIPT target disease, and nonreportable NIPT results. Sensitivity and specificity were calculated from the obtained data, and maternal age-specific PPV and NPV were estimated.

RESULTS

Of the 45 504 cases, 44 263 cases fulfilling the study criteria were included. The mean maternal age and gestational weeks at the time of procedure were 38.5 years and 13.1 weeks, respectively. Sensitivities were 99.78% (95% confidence interval [95% CI]: 98.78-99.96), 99.12% (95% CI: 96.83-99.76), and 100% (95% CI: 88.30-100) for trisomies 21, 18, and 13, respectively. Specificities were more than 99.9% for trisomies 21, 18, and 13, respectively. Maternal age-specific PPVs were more than 93%, 77%, and 43% at the age of 35 years for trisomies 21, 18, and 13, respectively.

CONCLUSION

The GeneTech NIPT data showed high sensitivity and specificity in the detection of fetal trisomies 21, 18, and 13 in high-risk pregnant women, and maternal age-specific PPVs were obtained. These results could provide more accurate and improved information regarding NIPT for genetic counseling in Japan.

Isolated echogenic intracardiac foci and the role of cell-free fetal DNA: A cost-effectiveness analysis

OBJECTIVES

Cell-free fetal DNA (cfDNA) has been increasingly incorporated into prenatal aneuploidy screening paradigms given its relatively high sensitivity for Down syndrome (DS). This is often the case when fetal ultrasonographic soft markers are present, such as the relatively common echogenic intracardiac focus (EIF). We sought to evaluate the cost-effectiveness of a screening strategy that included cfDNA screening when an isolated EIF is identified in a low-risk population with prior aneuploidy screening.

METHODS

A decision-analytic model was constructed using TreeAge software with probabilities derived from the literature. Our model compared cfDNA screening following isolated EIF detection in women less than 35 years with prior reassuring first trimester screen compared to a strategy of no further aneuploidy screening. Strategies were compared to generate an incremental cost-effectiveness ratio with a threshold of $100 000/quality-adjusted life year (QALY) and applied to a theoretical cohort.

RESULTS

The cfDNA strategy resulted in 21 fewer DS births and 52 additional QALYs, however, increased costs by $51.3 million. This yielded an incremental cost-effectiveness ratio of $986 503; therefore, it was not a cost-effective strategy.

CONCLUSION

In a low-risk population with prior reassuring aneuploidy screening, it is not cost effective to offer cfDNA after identification of an isolated EIF.

Physicians' perception toward non-invasive prenatal testing through the eye of the Rogers' diffusion of innovation theory in China

OBJECTIVE

Physicians' attitudes and adoption behavior toward the delivery of prenatal tests take vital significance for its influence on their professional practice and patient acceptance. This study aimed to identify how physicians have perceived the diffusion of non-invasive prenatal testing (NIPT) in China.

METHODS

A cross-sectional study was conducted from July 2016 to October 2016 in Shanghai, and Fujian and Sichuan Provinces in China. Physicians working on prenatal screening completed a self-report questionnaire. Following Roger's diffusion of innovation model, multivariable logistic regressions were performed separately for the following key elements of the theory which influence diffusion: physician-perceived attributes of NIPT, communication channels, the nature of the social system, the extent of change agent (who introduces innovations into a society), promotion efforts, and physicians' benefits from adopting NIPT.

RESULTS

Most specialists had a positive attitude (53.2 percent) toward NIPT, whereas 58.9 percent of physicians had already adopted NIPT in their clinical practice. Physician adoption of NIPT was positively associated with the strength of HTA evidence (p = .03), perceived communication frequency with colleagues (p = .04), adoption by other physicians (p = .07), hospital competition (p = .06), hospital teaching status (p = .02), perceived for-profit genetic testing company's promotion (p < .001), and perceived clinical practice skill improvement (p = .02). However, the adoption behavior toward NIPT may be negatively associated with physician-perceived ethical concerns of NIPT (p = .06).

CONCLUSION

Obstetricians and gynecologists' positive perceptions facilitate the adoption of NIPT. Combined with cost-effectiveness analysis of prenatal screening methods, health policy makers can promote the adoption of appropriate, cost-effective prenatal screening in pregnant women.

Non-invasive Prenatal Testing Using Fetal DNA

Non-invasive prenatal diagnosis (NIPD) is based on fetal DNA analysis starting from a simple peripheral blood sample, thus avoiding risks associated with conventional invasive techniques. During pregnancy, the fetal DNA increases to approximately 3-13% of the total circulating free DNA in maternal plasma. The very low amount of circulating cell-free fetal DNA (ccffDNA) in maternal plasma is a crucial issue, and requires specific and optimized techniques for ccffDNA purification from maternal plasma. In addition, highly sensitive detection approaches are required. In recent years, advanced ccffDNA investigation approaches have allowed the application of non-invasive prenatal testing (NIPT) to determine fetal sex, fetal rhesus D (RhD) genotyping, aneuploidies, micro-deletions and the detection of paternally inherited monogenic disorders. Finally, complex and innovative technologies such as digital polymerase chain reaction (dPCR) and next-generation sequencing (NGS) (exhibiting higher sensitivity and/or the capability to read the entire fetal genome from maternal plasma DNA) are expected to allow the detection, in the near future, of maternally inherited mutations that cause genetic diseases. The aim of this review is to introduce the principal ccffDNA characteristics and their applications as the basis of current and novel NIPT.

Recent trends in prenatal genetic screening and testing

Prenatal testing in recent years has been moving toward non-invasive methods to determine the fetal risk for genetic disorders without incurring the risk of miscarriage. Rapid progress of modern high-throughput molecular technologies along with the discovery of cell-free fetal DNA in maternal plasma led to novel screening methods for fetal chromosomal aneuploidies. Such tests are referred to as non-invasive prenatal tests (NIPTs), non-invasive prenatal screening, or prenatal cell-free DNA screening. Owing to many advantages, the adoption of NIPT in routine clinical practice was very rapid and global. As an example, NIPT has recently become a standard screening procedure for all pregnant women in the Netherlands. On the other hand, invasive sampling procedures remain important, especially for their diagnostic value in the confirmation of NIPT-positive findings and the detection of Mendelian disorders. In this review, we focus on current trends in the field of NIPT and discuss their benefits, drawbacks, and consequences in regard to routine diagnostics.

Current genetic counseling practice in the United States following positive non-invasive prenatal testing for sex chromosome abnormalities

The purpose of this study was to describe current genetic counseling practice in the United States following a non-invasive prenatal testing (NIPT) result positive for a sex chromosome abnormality (SCA). Screening for SCAs can be confounded by confined placental mosaicism, natural loss of the X chromosome from maternal cells during aging, and undiagnosed maternal SCA or copy number variant (CNV). Furthermore, with the exception of 45,X, individuals with SCAs usually have no ultrasound or postnatal findings. This makes follow-up for unresolved positive NIPT necessary; however, there are currently no clinical guidelines. This study used a cross-sectional design with an anonymous questionnaire to survey 176 genetic counselors. The majority of prenatal respondents always offered diagnostic testing (>88%) and anatomy ultrasound (~90%), but the percent consistently offering maternal karyotype (22%-52%) and postnatal evaluation (28%-87%) varied. Maternal karyotype was offered more often when NIPT was positive for 45,X or 47,XXX and patients had normal prenatal diagnostic testing (p < 0.02) or declined testing (p < 0.02). Offer of postnatal evaluation was more likely when diagnostic testing was declined (p < 0.001). The majority of pediatric providers always offered a postnatal karyotype for the newborn (>72%) but the percent offering maternal karyotype (6%-46%) varied widely. With the current inconsistencies, many newborns with undiagnosed SCAs who could benefit from growth hormone therapy, early intervention, and/or targeted surveillance may be missed. Therefore, there is a need for professional guidelines to help improve the consistency of clinical care for patients with NIPT results positive for SCAs.

An update on current prenatal testing options: first trimester and noninvasive prenatal testing

Prenatal genetic testing is rapidly evolving and requires that prenatal care providers stay up-to-date with accurate, evidence-based knowledge. Noninvasive prenatal testing (NIPT), first trimester maternal serum markers, and fetal nuchal translucency are the most recently developed screening tests added to the testing repertoire for detection of chromosomal disorders such as trisomy 21 (Down syndrome). NIPT is a new, highly accurate technique that uses maternal serum and is rapidly being introduced as a first trimester screening tool and increasingly being requested by pregnant women. The American College of Obstetricians and Gynecologists recommends that all pregnant women be offered first and second trimester screening options, regardless of risk status, but does not yet recommend NIPT. It is important for prenatal care providers to be aware of and understand these testing options in order to assist women and their families in making well-informed decisions during pregnancy. The purpose of this article is to update midwives and other prenatal care providers on the current prenatal genetic testing options available and how to appropriately offer and discuss them with their clients. We discuss how these tests work; what to do with the results; and most importantly, how to support and communicate accurate information to women and families as they navigate through an increasingly complicated array of testing choices.

Fetal RHD Genotyping Using Real-Time Polymerase Chain Reaction Analysis of Cell-Free Fetal DNA in Pregnancy of RhD Negative Women in South of Iran

BACKGROUND

Maternal-fetal RhD antigen incompatibility causes approximately 50% of clinically significant alloimmunization cases. The routine use of prophylactic anti-D immunoglobulin has dramatically reduced hemolytic disease of the fetus and newborn. Recently, fetal RHD genotyping in RhD negative pregnant women has been suggested for appropriate use of anti-D immunoglobulin antenatal prophylaxis and decrease unnecessary prenatal interventions.

MATERIALS AND METHODS

In this prospective cohort study, in order to develop a reliable and non-invasive method for fetal RHD genotyping, cell free fetal DNA (cffD- NA) was extracted from maternal plasma. Real-time quantitative polymerase chain reaction (qPCR) for detection of RHD exons 7, 5, 10 and intron 4 was performed and the results were compared to the serological results of cord blood cells as the gold standard method. SRY gene and hypermethylated Ras-association domain family member 1 (RASSF1A) gene were used to confirm the presence of fetal DNA in male and female fetuses, respectively.

RESULTS

Out of 48 fetuses between 8 and 32 weeks (wks) of gestational age (GA), we correctly diagnosed 45 cases (93.75%) of RHD positive fetuses and 2 cases (4.16%) of the RHD negative one. Exon 7 was amplified in one sample, while three other RHD gene sequences were not detected; the sample was classified as inconclusive, and the RhD serology result after birth showed that the fetus was RhD-negative.

CONCLUSION

Our results showed high accuracy of the qPCR method using cffDNA for fetal RHD genotyping and implicate on the efficiency of this technique to predict the competence of anti-D immunoglobulin administration.

Non-invasive prenatal testing for fetal chromosome abnormalities: review of clinical and ethical issues

Genomics-based non-invasive prenatal screening using cell-free DNA (cfDNA screening) was proposed to reduce the number of invasive procedures in current prenatal diagnosis for fetal aneuploidies. We review here the clinical and ethical issues of cfDNA screening. To date, it is not clear how cfDNA screening is going to impact the performances of clinical prenatal diagnosis and how it could be incorporated in real life. The direct marketing to users may have facilitated the early introduction of cfDNA screening into clinical practice despite limited evidence-based independent research data supporting this rapid shift. There is a need to address the most important ethical, legal, and social issues before its implementation in a mass setting. Its introduction might worsen current tendencies to neglect the reproductive autonomy of pregnant women.

High-resolution melting analysis for noninvasive prenatal diagnosis of IVS-II-I (G-A) fetal DNA in minor beta-thalassemia mothers

OBJECTIVES

The high-resolution melting (HRM) technique is fast, effective and successful method for mutation detection. The aim of this study was to determine the sensitivity and specificity of the HRM method for detection of a paternally inherited mutation in a fetus as a noninvasive prenatal diagnosis of β-thalassemia.

METHODS

Genomic DNAs were prepared from 50 β-thalassemia minor couples whose pregnancy was at risk for homozygous β-thalassemia. Ten milliliters of the maternal blood from each pregnant woman were collected and after separating plasma stored at -80 °C until analysis. The extracted DNAs were analyzed by HRM real-time PCR for detection of IVS-II-I (G-A) as a paternally inherited mutation. The gold standard was the result of a chorionic villus sampling by a standard reverse dot blotting test.

RESULTS

The sensitivity and specificity of HRM real-time PCR were 92.6% and 82.6%, respectively. Also, the positive and negative predictive values were 86.2% and 90.47%, respectively.

CONCLUSIONS

HRM real-time PCR was a sensitive and specific method for determining the paternally inherited mutation in the fetus at risk with thalassemia major.

Performance of Momguard, a new non-invasive prenatal testing protocol developed in Korea

Objective

To evaluate the performance of Momguard, non-invasive prenatal test (NIPT) for detecting trisomy (T) 21, T18, T13, and sex-chromosome abnormalities recently developed in Korea.

Methods

This preliminary study formed part of a large prospective cohort study conducted at Asan Medical Center, Seoul, Korea. Only pregnant women who underwent both NIPT and confirmatory karyotyping were included in this study. NIPT results were compared with those of karyotype analyses.

Results

Among 93 eligible cases, NIPT results could not be obtained in one case due to a low fetal cell-free DNA fraction. Based on NIPT, eight cases of fetal aneuploidies, including T21 (n=5), T18 (n=2), and T13 (n=1), were identified. For T21 and T18, the sensitivity and specificity of NIPT were both 100%, with a false-positive and false-negative rate of 0% and a positive-predictive value of 100%. One patient classified as having intermediate risk for T13 by NIPT was confirmed to have T13 by karyotyping, and there were no false-negative cases. No cases of sex-chromosome anomalies were detected by NIPT or karyotyping during the study period.

Conclusion

Momguard is a reliable screening tool for detecting T21 and T18. For T13 and sex-chromosome anomalies, further prospective studies are necessary to confirm its utility.

Discordant circulating fetal DNA and subsequent cytogenetics reveal false negative, placental mosaic, and fetal mosaic cfDNA genotypes

Background

The American College of Obstetrics and Gynecology (ACOG) and Maternal Fetal Medicine (MFM) Societies recommended that abnormal cfDNA fetal results should be confirmed by amniocentesis and karyotyping. Our results demonstrate that normal cfDNA results inconsistent with high-resolution abnormal ultrasounds should be confirmed by karyotyping following a substantial frequency of incorrect cfDNA results.

Methods

Historical review of our ~4,000 signed prenatal karyotypes found ~24% of reported abnormalities would not have been detected by cfDNA. Akron Children’s Hospital Cytogenetics Laboratory has completed 28 abnormal cfDNA cases among the 112 amniocenteses karyotyped.

Results

Following abnormal cfDNA results our karyotypes confirmed only 60% of the cfDNA results were consistent. Our cases found a normal cfDNA test result followed by a 20 weeks anatomical ultrasound detected a false negative trisomy 18 cfDNA result. One cfDNA result that reported trisomy 21 in the fetus was confirmed by karyotyping which also added an originally undetected balanced reciprocal translocation. Another reported karyotyped case followed by a repeated microarray of pure fetal DNA, together revealed one phenotypically normal newborn with a complex mosaic karyotype substantially decreasing the newborn’s eventual reproductive fitness. This second case establishes the importance of karyotyping the placenta and cord or peripheral blood when inconsistent or mosaic results are identified following an abnormal cfDNA result with a normal newborn phenotype without a prenatal karyotype.

Conclusions

These Maternal Fetal Medicine referrals demonstrate that positive NIPT results identify an increased abnormal karyotypic frequency as well as a substantial proportion of discordant fetal results. Our results found: (1) a normal NIPT test result followed by a 20 week anatomical ultrasound detected a false negative trisomy 18 NIPT result, (2) a substantial proportion of abnormal NIPT tests identify chromosomal mosaicism that may or may not be confined to the placenta, (3) follow up karyotyping should be completed on the newborn placenta and peripheral blood when the amniocyte karyotype does not confirm the NIPT reported abnormality in order to identify ongoing risk of developing mosaic symptoms, and (4) karyotyping all high risk fetuses tested by amniocentesis defines the 24% of chromosome abnormalities not currently screened by NIPT.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0569-y) contains supplementary material, which is available to authorized users.

Physician liability and non-invasive prenatal testing

Although non-invasive prenatal testing (NIPT) marks a notable development in the field of prenatal genetic testing, there are some physician liability considerations raised by this technology. As NIPT is still emerging as the standard of care and is just starting to receive provincial funding, the question arises of whether physicians are obligated to disclose the availability of NIPT to eligible patients as part of the physician-patient discussion about prenatal screening and diagnosis. If NIPT is discussed with patients, it is important to disclose the limitations of this technology with respect to its accuracy and the number of disorders that it can detect when compared with invasive diagnostic options. A failure to sufficiently disclose these limitations could leave patients with false assurances about the health of their fetuses and could raise informed consent and liability issues, particularly if a child is born with a disability as a result.

Discrepancy in fetal sex assignment between cell free fetal DNA and ultrasound

Noninvasive prenatal testing utilizing free fetal DNA is commonly used in pregnancy to screen for trisomy 13, 18, 21 and also fetal sex aneuploidy. We report on two cases of discrepancy between phenotypic and genotypic sex and potential medical implications. In our first case, a patient with known male gender via cell free fetal DNA (cffDNA) testing had an ultrasound at 18 weeks' gestation, which identified Dandy-Walker malformation and female-appearing ambiguous genitalia. As Dandy-Walker malformation could not be considered isolated in the presence of ambiguous genitalia, this finding allowed for more complete counseling of the parents as well as extensive genetic workup. Our second case involved a fetus with intrauterine growth restriction diagnosed by ultrasound and normal-appearing female genitalia. After birth, adrenal insufficiency was diagnosed and chromosome analysis identified normal male chromosomes. These two cases showed that fetal sex determination by cffDNA can be used as a tool for earlier identification of affected pregnancies, allowing for parental decision-making, genetic testing and earlier intervention.

Evaluation of a Modified DNA Extraction Method for Isolation of Cell-Free Fetal DNA from Maternal Serum

BACKGROUND

Discovery of short cell free fetal DNA (cffDNA) fragments in maternal plasma has created major changes in the field of prenatal diagnosis. The use of cffDNA to set up noninvasive prenatal test is limited due to the low concentration of fetal DNA in maternal plasma therefore, employing a high efficiency extraction method leads to more accurate results. The aim of this study was to evaluate the efficiency of Triton/Heat/Phenol (THP) protocol in comparison with the QIAamp DNA Blood mini Kit for cffDNA purification.

METHODS

In order to evaluate the efficiency of THP protocol, DNA of Rhesus D (RhD) negative pregnant women's plasma was collected, then real-time PCR for RHD exon 7 was performed. The Ct value data of real time PCR obtained by two different methods were compared and after delivery serology test on cord blood was done to validate the real time PCR results.

RESULTS

The results indicated significant differences between two extraction methods (p=0.001). The mean±SD of Ct-value using THP protocol was 33.8±1.6 and 36.1±2.47 using QIAamp DNA Blood mini Kit.

CONCLUSION

Our finding demonstrated that THP protocol was more effective than the QIAamp DNA Blood mini Kits for cffDNA extraction and lead to decrease the false negative results.

Non-Invasive Testing, Non-Invasive Counseling

This article describes a new prenatal genetic test that is painless, early, and increasingly available. State legislatures have reacted by prohibiting abortion for reason of fetal sex or of fetal diagnosis and managing genetic counseling. This article explores these legislative responses and considers how physicians and genetic counselors currently communicate post-testing options. The article then examines the challenges ahead for genetic counseling, particularly in light of the troubling grip of abortion politics on conversations about prenatal diagnosis.

What does next-generation sequencing mean for prenatal diagnosis?

The ability to gain genetic information from the fetus in the mother's blood during pregnancy has been a long desired goal of research in prenatal medicine. The detection of fetal DNA in maternal blood, coupled with the development of the powerful techniques of next-generation sequencing finally transferred this analysis into clinical practice. Following the commercial introduction of noninvasive prenatal testing for aneuploidies, there has been a very strong demand, which has fostered an extreme rapid development and improvement of technology. Publications in this field are so numerous so that it is challenging to keep up with the latest state of the art. Here, we describe the current basic concepts of cell-free DNA-based noninvasive prenatal testing, give an overview of the currently commercially available tests and the chromosomal aberrations that can be identified. We also present current and future concepts for the implementation of cell-free DNA testing into clinical care.

Uptake of noninvasive prenatal testing at a large academic referral center

OBJECTIVE

Noninvasive prenatal testing (NIPT) is a recently developed risk-assessment technique with high sensitivity and specificity for fetal aneuploidy. The effect NIPT has had on traditional screening and diagnostic testing has not been clearly demonstrated. In this study, NIPT uptake and subsequent changes in the utilization of first-trimester screen (FTS), chorionic villus sampling (CVS), and amniocentesis in a single referral center is reported.

STUDY DESIGN

Monthly numbers of NIPT (in high-risk patients), FTS, CVS, and amniocentesis were compared between a 35-month baseline period (April 2009 through February 2012) before introduction of NIPT, and the initial 16 months following NIPT introduction divided in 4-month quarters beginning in March 2012 through June 2013.

RESULTS

A total of 1265 NIPT, 6637 FTS, 251 CVS, and 1134 amniocentesis were recorded over the 51-month study period in singleton pregnancies of women who desired prenatal screening and diagnostic testing. NIPT became the predominant FTS method by the second quarter following its introduction, increasing by 55.0% over the course of the study period. Total first-trimester risk assessments (NIPT+FTS) were not statistically different following NIPT (P = .312), but average monthly FTS procedures significantly decreased following NIPT introduction, decreasing by 48.7% over the course of the study period. Average monthly CVS and amniocentesis procedures significantly decreased following NIPT introduction, representing a 77.2% and 52.5% decrease in testing, respectively. Screening and testing per 100 morphological ultrasounds followed a similar trend.

CONCLUSION

NIPT was quickly adopted by our high-risk patient population, and significantly decreased alternate prenatal screening and diagnostic testing in a short period of time.

QF-PCR rapid aneuploidy screen and aCGH analysis of cell free fetal (cff) DNA in supernatant of compromised amniotic fluids (AF)

OBJECTIVE

The aim of this study was to determine whether cell free fetal (cff) DNA in residual amniotic fluid (AF) supernatant obtained from bloody, low-volume and late gestation samples can be used for prenatal diagnosis by quantitative fluorescence polymerase chain reaction (QF-PCR) and array comparative genomic hybridization (aCGH).

METHOD

A total of 49 compromised AFs were analyzed in this case-control, double-blinded study. The samples were processed through: a conventional cytogenetic approach utilizing Fluorescence in situ Hybridization and/or karyotype (Approach I); QF-PCR analysis to establish the presence of maternal cell contamination (MCC) (Approach II) and a newly proposed approach using AF supernatant cff DNA (Approach III). Data on clinical impact and turn-around-time was collected.

RESULTS

Evidence of MCC was not detected in any of the cff DNA samples, and informative results were provided for all cases, including nine aneuploidies. In contrast, the conventional approach (I) failed to provide results either due to MCC or culture failure in a significant proportion of cases. An adequate amount of quality cff DNA was obtained for successful aCGH testing.

CONCLUSION

We have shown that it is feasible to isolate pure cff DNA from routinely discarded AF supernatant to perform QF-PCR and microarray analyses, providing timely and informative results even for problematic grossly bloody and otherwise compromised AF samples or culture failures.