Systematic evidence-based review: The application of noninvasive prenatal screening using cell-free DNA in general-risk pregnancies.

PURPOSE: Noninvasive prenatal screening (NIPS) using cell-free DNA has been assimilated into prenatal care. Prior studies examined clinical validity and technical performance in high-risk populations. This systematic evidence review evaluates NIPS performance in a general-risk population. METHODS: Medline (PubMed) and Embase were used to identify studies examining detection of Down syndrome (T21), trisomy 18 (T18), trisomy 13 (T13), sex chromosome aneuploidies, rare autosomal trisomies, copy number variants, and maternal conditions, as well as studies assessing the psychological impact of NIPS and the rate of subsequent diagnostic testing. Random-effects meta-analyses were used to calculate pooled estimates of NIPS performance (P < .05). Heterogeneity was investigated through subgroup analyses. Risk of bias was assessed. RESULTS: A total of 87 studies met inclusion criteria. Diagnostic odds ratios were significant (P < .0001) for T21, T18, and T13 for singleton and twin pregnancies. NIPS was accurate (≥99.78%) in detecting sex chromosome aneuploidies. Performance for rare autosomal trisomies and copy number variants was variable. Use of NIPS reduced diagnostic tests by 31% to 79%. Conclusions regarding psychosocial outcomes could not be drawn owing to lack of data. Identification of maternal conditions was rare. CONCLUSION: NIPS is a highly accurate screening method for T21, T18, and T13 in both singleton and twin pregnancies.

Tobacco and Cannabis Use During Pregnancy.

OBJECTIVES: Nicotine (NIC) use during pregnancy can influence markers used in biochemical maternal serum screening. This study was designed to determine prevalence of disclosed tobacco smokers in our patient population and to compare disclosed tobacco smoking status with the presence of serum nicotine and a common tetrahydrocannabinol (THC) metabolite. METHODS: A deidentified dataset of disclosed smoking status for quadruple (Quad) screens was obtained. Residual serum submitted for Quad screens was obtained from frozen storage and analyzed for NIC and THC metabolites. RESULTS: Of specimens that had corresponding responses to the smoking history question on the patient history form, 7.2% (n = 1,783 of 24,611) specified that the patient was a tobacco smoker. Of the 271 specimens biochemically analyzed for NIC and THC metabolites, disclosed tobacco smokers had the highest prevalence of detectable NIC and THC metabolites. THC product use was most prevalent in patients categorized as probable tobacco smokers based on cotinine concentrations, as well as in younger patients. CONCLUSIONS: Prevalence and concentration of NIC and THC metabolites vary based on disclosed tobacco smoker status. Biochemical testing may increase sensitivity for the identification of NIC and THC status over self-reporting.

Detection of maternal X chromosome abnormalities using single nucleotide polymorphism-based noninvasive prenatal testing.

BACKGROUND: Maternal X chromosome abnormalities may cause discordant results between noninvasive prenatal screening tests and diagnostic evaluation of the fetus/newborn, leading to unnecessary invasive testing. Women with X chromosome abnormalities are at increased risk for reproductive, pregnancy, or other health complications, which may be reduced or ameliorated by early diagnosis, monitoring, and intervention. OBJECTIVE: This study aimed to validate a single nucleotide polymorphism-based noninvasive prenatal test to identify X chromosome abnormalities of maternal origin. STUDY DESIGN: All tests unable to evaluate fetal risk for aneuploidy because of uninformative algorithm results were eligible for inclusion. Two groups of cases were prospectively identified: Group A (n=106) where a maternal X chromosome abnormality was suspected and Group B (control group, n=107) where a fetal chromosome abnormality involving chromosome 13, 18, 21, or X was suspected but did not meet criteria for reporting. Maternal DNA was isolated from the plasma-depleted cellular pellet and sent to a reference laboratory for blinded analysis using chromosomal microarray. A chromosome abnormality involving chromosomes 13, 18, 21, or X was reported by the reference laboratory if ≥5 Mb in size and present in ≥20% of the DNA. RESULTS: A maternal X chromosome abnormality was suspected in 1/1305 tests (149/194,385; 0.08%). In Group A, a maternal X chromosome abnormality was confirmed in 100/106 cases (94.3% positive predictive value, 1-sided 97.5% confidence interval, 88.1%-100.0%). Turner syndrome was the most commonly suspected maternal abnormality (58/106, 54.7%), with confirmation of mosaic or nonmosaic 45,X by microarray in 38/58 (65.5%) cases. Noninvasive prenatal screening tests suspected the presence of maternal 47,XXX with or without mosaicism in 40/106 (37.7%) cases, confirmed by microarray in 38/40 (95.0%). In Group B (n=107), no maternal microarray abnormalities were reported, providing a negative predictive value of 100% (1-sided 97.5% confidence interval, 96.6%-100.0%). CONCLUSION: When noninvasive prenatal testing suspected a maternal X chromosome abnormality, maternal microarray confirmed an X chromosome abnormality with 94.3% positive predictive value. Of the maternal X chromosome abnormalities detected by array, >50% were 45,X. When fetal chromosome abnormalities involving chromosomes 13, 18, 21, or X were suspected, no maternal chromosome abnormalities were reported, yielding a negative predictive value of 100%. Women with maternal X abnormalities suspected with noninvasive prenatal testing may be at increased risk for reproductive and health complications; early evaluation and treatment may prevent long-term consequences or disability.

Delineating the Clinical Spectrum Associated With Xq25q26.2 Duplications: Report of 2 Families and Review of the Literature.

To date, 13 patients with interstitial microduplications involving Xq25q26.2 have been reported. Here, we report 6 additional patients from 2 families with duplications involving Xq25q26.2. Family I carries a 5.3-Mb duplication involving 26 genes. This duplication was identified in 3 patients and was associated with microcephaly, growth failure, developmental delay, and dysmorphic features. Family II carries an overlapping 791-kb duplication that involves 3 genes. This duplication was identified in 3 patients and was associated with learning disability and speech delay. The size and gene content of published overlapping Xq25q26.2 duplications vary, making it difficult to define a critical region or establish a genotype-phenotype correlation. However, patients with overlapping duplications have been found to share common clinical features including microcephaly, growth failure, intellectual disability, learning difficulties, and dysmorphic features. The 2 families presented here provide additional insight into the phenotypic spectrum and clinical significance of duplications in this region.

Xq11.1-11.2 deletion involving ARHGEF9 in a girl with autism spectrum disorder.

We report an 8-year-old female with autism spectrum disorder (ASD), intellectual disability and speech delay who was found to carry a de novo 82 kb deletion of chromosome Xq11.1-11.2 involving the ARHGEF9 gene on chromosomal microarray. So far, 11 patients with point mutations, disruptions due to chromosomal rearrangements and deletions involving ARHGEF9 have been reported in the literature. ARHGEF9-related disorders comprise a wide phenotypic spectrum, including behavior disorders, autism spectrum disorder, intellectual disability, hyperekplexia and infantile epileptic encephalopathy. ARHGEF9 encodes for collybistin which plays an important role in post synaptic clustering of glycine and inhibitory gamma-aminobutyric acid receptors along with its scaffolding partner, gephyrin. The reduction of inhibitory receptor clusters in brain has been proposed as a plausible underlying pathophysiological mechanism. With this report, we provide further evidence for the role of ARHGEF9 in neurocognitive function, its implication in ASD, and review the clinical features of previously published individuals with ARHGEF9-related intellectual disability.

A cost-effectiveness analysis of cell free DNA as a replacement for serum screening for Down syndrome.

OBJECTIVE: The aim of this article is to determine the cost effectiveness of cell free DNA (cfDNA) as a replacement for integrated screening using a societal cost perspective. METHOD: This study used Monte-Carlo simulation with one-way and probabilistic sensitivity analysis. RESULTS: Cell free DNA is more effective and less costly than integrated screening. The incremental cost-effectiveness ratio for cfDNA relative to the integrated test was -$277 955 per case detected (95th percent confidence interval -$881 882 to $532 785). CONCLUSION: Cell free DNA screening is a cost-effective replacement for maternal serum screening when the lifetime costs of Down syndrome live births are considered. The adoption of cfDNA screening would save approximately $277 955 for each additional case detected over integrated screening.

Genetic counselor review of genetic test orders in a reference laboratory reduces unnecessary testing.

Genetic tests are routinely ordered by health care providers (HCPs) within a wide range of medical specialties. Many providers have limited knowledge or experience with ordering and interpreting genetic tests; thus, test order errors are common. Rigorous review of genetic test orders by genetic counselors (GCs) can provide a direct financial benefit to medical institutions, patients and insurers. GCs at ARUP (Associated Regional University Pathologists) Laboratories routinely perform a preanalytic assessment of complex molecular genetic test orders that includes reviewing clinical and family history information and considering the clinical utility and cost-effectiveness of ordered tests. GCs contact the ordering institution and/or HCP as needed to collect additional clinical information and confirm the test order or suggest alternative testing based on the provided information. A retrospective review of the GC-facilitated test changes over a 21-month period at ARUP laboratories was performed. Approximately 26% of all requests for complex genetic tests assessing germ line mutations were changed following GC review. Testing fees associated with canceled tests were summed to estimate the cost-savings resulting from GC-facilitated test reviews. The test review process resulted in an average reduction in charges to the referring institutions of $48,000.00 per month. GC review of genetic test orders for appropriateness and clinical utility reduces healthcare costs to hospitals, insurers, and patients.

A tradeoff analysis of risk cutoffs for the quadruple serum screen for Down syndrome.

OBJECTIVES: In maternal serum screening for Down syndrome, a cutoff of 1 : 270 is often used as a decision point to recommend invasive confirmatory testing. However, it has not been established how well this or any other cutoff relates to patient preferences, that is, the values that pregnant women attach to various screening outcomes. The purpose of this study was to examine the clinical and economic tradeoffs of a wide range of risk cutoffs for the quadruple screen. METHODS: Screening costs and outcomes for multiple risk cutoffs were modeled using a Monte Carlo simulation. RESULTS: The optimal cutoff for maternal serum screening depends on the relative values placed by the patient on different outcomes. Total societal costs were similar across the range of cutoffs. CONCLUSIONS: Given that different screening outcomes are optimized by different cutoff values, a one-size-fits-all approach may not be appropriate.

The impact of utilization of early aneuploidy screening on amniocenteses available for training in obstetrics and fetal medicine.

OBJECTIVE: First-trimester aneuploidy screening has high detection rates and low false-positive rates. Their use as well as the implementation of non-invasive prenatal testing may affect specialty training in prenatal diagnosis procedures. STUDY DESIGN: Descriptive study of first-trimester aneuploidy screening and amniocentesis in an obstetric training program. Screening methods were tracked from their introduction in 2004 through 2011. The volume of amniocentesis procedures from 2000 to 2011 was evaluated. RESULTS: First-trimester screening tests increased from 283 to 1225 between 2005 and 2011, whereas genetic amniocenteses declined from 460 to 168 during the same period. The percent of older women who chose a first-trimester screen test rose from 12.7% to 44.2% CONCLUSION: First-trimester screening options reduce genetic amniocenteses available for training. Fetal medicine and general obstetrics training programs need to evaluate their clinical experience and determine whether simulation training methods are needed for education.

Chromosomal loss of 3q26.3-3q26.32, involving a partial neuroligin 1 deletion, identified by genomic microarray in a child with microcephaly, seizure disorder, and severe intellectual disability.

Neuroligin 1 (NLGN1) is one of five members of the neuroligin gene family and may represent a candidate gene for neurological disorders, as members of this family are involved in formation and remodeling of central nervous system synapses. NLGN1 is expressed predominantly in the central nervous system, where it dimerizes and then binds with ß-neurexin to form a functional synapse. Mutations in neurexin 1 (NRXN1) as well as two other members of the neuroligin family, NLGN3 and NLGN4, have been associated with autism and mutations in NLGN4 have also been associated with intellectual disability, seizures, and EEG abnormalities. Genomic microarray is recommended for the detection of chromosomal gains or losses in patients with intellectual disability and multiple congenital anomalies. Results of uncertain significance are not uncommon. Parental studies can provide additional information by demonstrating that the imbalance is either de novo or inherited, and therefore is more or less likely to be causative of the clinical phenotype. However, the possibility that even inherited deletions and duplications may play a role in the phenotype of the proband cannot be excluded as many copy number variants associated with neurodevelopmental conditions show incomplete penetrance and may be inherited from an unaffected parent. Here, we report on a patient with a 2.2 Mb deletion at 3q26.3-3q26.32-encompassing the terminal end of NLGN1 and the entire NAALADL2 gene-detected by genomic microarray, and confirmed by FISH and real-time quantitative PCR. The same size deletion was subsequently found in her healthy, asymptomatic, adult mother.

Practice guidelines for communicating a prenatal or postnatal diagnosis of Down syndrome: recommendations of the national society of genetic counselors.

Down syndrome is one of the most common conditions encountered in the genetics clinic. Due to improvements in healthcare, educational opportunities, and community inclusion over the past 30 years, the life expectancy and quality of life for individuals with Down syndrome have significantly improved. As prenatal screening and diagnostic techniques have become more enhanced and widely available, genetic counselors can expect to frequently provide information and support following a new diagnosis of Down syndrome. This guideline was written for genetic counselors and other healthcare providers regarding the communication of a diagnosis of Down syndrome to ensure that families are consistently given up-to-date and balanced information about the condition, delivered in a supportive and respectful manner.