Accuracy of fetal fraction measurements in a single-nucleotide polymorphism-based noninvasive prenatal test.

Background: Noninvasive prenatal testing (NIPT) for fetal aneuploidy relies on the analysis of fetoplacental cell-free DNA (cfDNA) found in maternal plasma. A minimum cfDNA fetal fraction (FF) is required for reliable test performance, but some methods may have suboptimal accuracy for FF measurement. This study investigated the accuracy of a single-nucleotide polymorphism- (SNP-) based NIPT method to assess FF.

Reproductive Carrier Screening: Identifying Families at Risk for Familial Hypercholesterolemia in the United States.

Background: Familial hypercholesterolemia is a treatable genetic condition but remains underdiagnosed. We reviewed the frequency of pathogenic or likely pathogenic (P/LP) variants in the gene in female individuals receiving reproductive carrier screening.

Methods: This retrospective observational study included samples from female patients (aged 18-55 years) receiving a 274-gene carrier screening panel from January 2020 to September 2022.

Overview of Noninvasive Prenatal Testing (NIPT) for the Detection of Fetal Chromosome Abnormalities; Differences in Laboratory Methods and Scope of Testing.

Although nearly all noninvasive prenatal testing is currently based on analyzing circulating maternal cell-free DNA, the technical methods usedvary considerably. We review the different methods. Based on validation trials and clinical experience, there are mostly relatively small differences in screening performance for trisomies 21, 18, and 13 in singleton pregnancies.

Reproductive Carrier Screening Results With Maternal Health Implications During Pregnancy.

Objective: To identify conditions on a reproductive carrier screening panel with the potential for carrier manifestations during pregnancy and review the implications for obstetric care.

Methods: This was a retrospective cross-sectional study of consecutive samples from female patients aged 18-55 years submitted to a commercial laboratory for a 274-gene carrier screening panel (January 2020 to September 2022). A literature review was performed to identify genes on the panel with potential for pregnancy complications in carriers.

Positive predictive values and outcomes for uninformative cell-free DNA tests: An Italian multicentric Cytogenetic and cytogenomic Audit of diagnOstic testing (ICARO study).

Objectives: To establish the positive predictive values (PPV) of cfDNA testing based on data from a nationwide survey of independent clinical cytogenetics laboratories.

Methods: Prenatal diagnostic test results obtained by Italian laboratories between 2013 and March 2020 were compiled for women with positive non-invasive prenatal tests (NIPT), without an NIPT result, and cases where there was sex discordancy between the NIPT and ultrasound. PPV and other summary data were reviewed.

Assessment of an automated approach for variant interpretation in screening for monogenic disorders: A single-center study.

Background: Automation has been introduced into variant interpretation, but it is not known how automated variant interpretation performs on a stand-alone basis. The purpose of this study was to evaluate a fully automated computerized approach.

Method: We reviewed all variants encountered in a set of carrier screening panels over a 1-year interval.

A Critical Evaluation of Validation and Clinical Experience Studies in Non-Invasive Prenatal Testing for Trisomies 21, 18, and 13 and Monosomy X.

Non-invasive prenatal testing (NIPT) for trisomies 21, 18, 13 and monosomy X is widely utilized with massively parallel shotgun sequencing (MPSS), digital analysis of selected regions (DANSR), and single nucleotide polymorphism (SNP) analyses being the most widely reported methods. We searched the literature to find all NIPT clinical validation and clinical experience studies between January 2011 and January 2022. Meta-analyses were performed using bivariate random-effects and univariate regression models for estimating summary performance measures across studies.

Non-invasive prenatal screening for fetal triploidy using single nucleotide polymorphism-based testing: Differential diagnosis and clinical management in cases showing an extra haplotype.

Objective: An extra haplotype is infrequently encountered in single nucleotide polymorphism(SNP)-based non-invasive prenatal testing (NIPT) and is usually attributed to an undetected twin or triploidy. We reviewed a large series to establish relative frequencies of these outcomes and identify alternative causes.

Methods: In 515,804 women receiving NIPT from September 2017 through March 2019, all results with an extra haplotype were reviewed.

Non-invasive prenatal testing in the management of twin pregnancies.

Twin pregnancies are common and associated with pregnancy complications and adverse outcomes. Prenatal clinical management is intensive and has been hampered by inferior screening and less acceptable invasive testing. For aneuploidy screening, meta-analyses show that non-invasive prenatal testing (NIPT) through analysis of cell-free DNA (cf-DNA) is superior to serum and ultrasound-based tests.

Performance of conventional cytogenetic analysis on chorionic villi when only one cell layer, cytotrophoblast or mesenchyme alone, is analyzed.

Objective: To provide an estimation of the probability of error when chorionic villi (CV) cytogenetic analysis is limited to a single placental layer; either a direct preparation (Dir) or long-term culture (LTC).

Methods: We retrospectively reviewed cytogenetic studies on 81,593 consecutive CV samples in which both Dir and LTC were analyzed. All mosaic cases received amniocentesis.

The origins of aneuploidy research consortium.

The presence of high levels of aneuploidy in oocytes and early embryos and their fate is of considerable scientific and clinical importance. The Origins of Aneuploidy Research Consortium (OARC) was established to promote interdisciplinary communication and collaborative research into this topic. Under the umbrella of OARC, a series of papers has now been published in this Special Issue of Prenatal Diagnosis.

Uniparental disomy: Origin, frequency, and clinical significance.

Uniparental disomy (UPD) is defined as two copies of a whole chromosome derived from the same parent. There can be multiple mechanisms that lead to UPD; these are reviewed in the context of contemporary views on the mechanism leading to aneuploidy. Recent studies indicate that UPD is rare in an apparently healthy population and also rare in spontaneous abortion tissues.

Review of epidemiological factors (other than maternal age) that determine the prevalence of common autosomal trisomies.

The birth prevalence of each common autosomal trisomy (21, 18 and 13) increases with advancing maternal age and this is the most important epidemiological risk factor. Prevalence during pregnancy is also dependent on gestational age. Other factors claimed to influence prevalence include paternal age, ethnicity, family history, premature reproductive aging, parity, twinning, smoking, environmental exposures, maternal medical conditions, and predispositions.

Aneuploidy in first trimester chorionic villi and spontaneous abortions: Windows into the origin and fate of aneuploidy through embryonic and fetal development.

Objective: To review the mosaic autosomal trisomies in chorionic villi sample (CVS) trophoblasts, mesenchyme, and both cell lineages and to compare them with trisomies in spontaneous abortions.

Methods: Mosaic autosomal trisomies from 76 102 diagnostic CVS tests were classified as involving trophoblasts, involving mesenchyme, or present in both. Autosomal trisomies in products of conception were based on 18 published studies.

Correction: Clinical experience with carrier screening in a general population: support for a comprehensive pan-ethnic approach.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Clinical experience with carrier screening in a general population: support for a comprehensive pan-ethnic approach.

Purpose: To present results from a large cohort of individuals receiving expanded carrier screening (CS) in the United States.

Methods: Single-gene disorder carrier status for 381,014 individuals was determined using next-generation sequencing (NGS) based CS for up to 274 genes. Detection rates were compared with literature-reported values derived from disease prevalence and carrier frequencies.

Combining the use of a fetal fraction-based risk algorithm and probability of an informative redraw in noninvasive prenatal testing for fetal aneuploidy.

Some women undergoing noninvasive prenatal testing (NIPT) do not receive an informative result due to low fetal fraction (FF). A proportion of these are at increased risk for fetal trisomy 13, 18, or triploidy, while others have no change from their prior risk. Women with an initial uninformative NIPT need to be counseled about any such change in their risk for fetal abnormality and also the probability that a redraw will be informative.

Cell-free DNA fetal fraction in twin gestations in single-nucleotide polymorphism-based noninvasive prenatal screening.

Objectives: The performance of noninvasive prenatal screening (NIPS) for fetal aneuploidy in twin pregnancies is dependent on the amount of placentally derived cell-free DNA, the "fetal fraction (FF)," present in maternal plasma. We report FF values in monozygotic (MZ) and dizygotic (DZ) pregnancies.

Methods: We reviewed FF in pregnancies at 10 to 20 completed weeks gestational age based on single-nucleotide polymorphism (SNP)-based NIPS where zygosity was routinely established in twin pregnancies.