RASopathies are the most common set of monogenic syndromes identified by exome sequencing for nonimmune hydrops fetalis: A systematic review and meta-analysis.

RASopathies are a group of malformation syndromes known to lead to nonimmune hydrops fetalis (NIHF) in severe presentations. Pathogenic variants can be de novo or parentally inherited. Despite being a known frequent presentation, the fraction of monogenic NIHF cases due to RASopathies is limited in the literature. Also, the specific parental contribution of RASopathies to NIHF is not well described. Our objective was to review pooled exome sequencing (ES) diagnostic yield of RASopathies for NIHF and to determine the parental contribution of RASopathy to NIHF. We performed a systematic review of prenatal ES studies from January 1, 2000 to August 1, 2022. Thirty-six studies met inclusion criteria. Cases with RASopathy gene variants were reviewed. NIHF cases were further classified as isolated or non-isolated. Thirty-six ES studies including 46 pregnancies with NIHF and a diagnosed RASopathy were reviewed. Forty-four diagnostic variants and 2 variants of uncertain significance in 12 RASopathy genes were identified. Expanding on what was previously published, a total of 506 NIHF cases were extracted with 191 cases yielding a positive diagnosis by ES. The overall rate of RASopathy diagnosis in clinically diagnosed NIHF cases was 9% (44/506). The rate of RASopathy diagnosis among NIHF cases with positive genetic diagnosis by ES was 23% (44/191). Of the 46 cases identified, 13 (28%) variants were parentally inherited; specifically, 5/13 (38%) maternal, 3/13 (23%) paternal, 2/13 (15%) biparental, and 3/13 (23%) unspecified. Majority of NIHF cases 29/46 (63%) were isolated. Among NIHF cases with positive ES diagnoses, RASopathy diagnostic yield by ES was 23%. NIHF secondary to RASopathies was parentally inherited in 28% of cases. Most cases of NIHF due to RASopathy were isolated, with no prenatal detection of associated anomalies.

Separate transcriptionally regulated pathways specify distinct classes of sister dendrites in a nociceptive neuron.

The dendritic processes of nociceptive neurons transduce external signals into neurochemical cues that alert the organism to potentially damaging stimuli. The receptive field for each sensory neuron is defined by its dendritic arbor, but the mechanisms that shape dendritic architecture are incompletely understood. Using the model nociceptor, the PVD neuron in C. elegans, we determined that two types of PVD lateral branches project along the dorsal/ventral axis to generate the PVD dendritic arbor: (1) Pioneer dendrites that adhere to the epidermis, and (2) Commissural dendrites that fasciculate with circumferential motor neuron processes. Previous reports have shown that the LIM homeodomain transcription factor MEC-3 is required for all higher order PVD branching and that one of its targets, the claudin-like membrane protein HPO-30, preferentially promotes outgrowth of pioneer branches. Here, we show that another MEC-3 target, the conserved TFIIA-like zinc finger transcription factor EGL-46, adopts the alternative role of specifying commissural dendrites. The known EGL-46 binding partner, the TEAD transcription factor EGL-44, is also required for PVD commissural branch outgrowth. Double mutants of hpo-30 and egl-44 show strong enhancement of the lateral branching defect with decreased numbers of both pioneer and commissural dendrites. Thus, HPO-30/Claudin and EGL-46/EGL-44 function downstream of MEC-3 and in parallel acting pathways to direct outgrowth of two distinct classes of PVD dendritic branches.

The clinical utility of DNA-based screening for fetal aneuploidy by primary obstetrical care providers in the general pregnancy population.

OBJECTIVE: To assess the clinical utility of cell-free DNA (cfDNA)-based screening for aneuploidies offered through primary obstetrical care providers to a general pregnancy population. METHODS: Patient educational materials were developed and validated and providers were trained. Serum was collected for reflexive testing of cfDNA failures. Providers and patients were surveyed concerning knowledge, decision making, and satisfaction. Pregnancy outcome was determined by active or passive ascertainment. RESULTS: Between September 2014 and July 2015, 72 providers screened 2,691 women. The five largest participating practices increased uptake by 8 to 40%. Among 2,681 reports, 16 women (0.6%) were screen-positive for trisomy 21, 18, or 13; all saw genetic professionals. Twelve were confirmed (positive predictive value (PPV), 75%; 95% CI, 48-93%) and four were false-positives (0.15%). Of 150 failures (5.6%), 79% had a negative serum or subsequent cfDNA test; no aneuploidies were identified. Of 100 women surveyed, 99 understood that testing was optional, 96 had their questions answered, and 95 received sufficient information. Pretest information was provided by the physician/certified nurse midwife (55) or office nurse/educator (40); none was provided by genetic professionals. CONCLUSION: This first clinical utility study of cfDNA screening found higher uptake rates, patient understanding of basic concepts, and easy incorporation into routine obstetrical practices. There were no reported cases of aneuploidy among cfDNA test failures.Genet Med advance online publication 12 January 2017.

Karyotype versus microarray testing for genetic abnormalities after stillbirth.

BACKGROUND: Genetic abnormalities have been associated with 6 to 13% of stillbirths, but the true prevalence may be higher. Unlike karyotype analysis, microarray analysis does not require live cells, and it detects small deletions and duplications called copy-number variants. METHODS: The Stillbirth Collaborative Research Network conducted a population-based study of stillbirth in five geographic catchment areas. Standardized postmortem examinations and karyotype analyses were performed. A single-nucleotide polymorphism array was used to detect copy-number variants of at least 500 kb in placental or fetal tissue. Variants that were not identified in any of three databases of apparently unaffected persons were then classified into three groups: probably benign, clinical significance unknown, or pathogenic. We compared the results of karyotype and microarray analyses of samples obtained after delivery. RESULTS: In our analysis of samples from 532 stillbirths, microarray analysis yielded results more often than did karyotype analysis (87.4% vs. 70.5%, P<0.001) and provided better detection of genetic abnormalities (aneuploidy or pathogenic copy-number variants, 8.3% vs. 5.8%; P=0.007). Microarray analysis also identified more genetic abnormalities among 443 antepartum stillbirths (8.8% vs. 6.5%, P=0.02) and 67 stillbirths with congenital anomalies (29.9% vs. 19.4%, P=0.008). As compared with karyotype analysis, microarray analysis provided a relative increase in the diagnosis of genetic abnormalities of 41.9% in all stillbirths, 34.5% in antepartum stillbirths, and 53.8% in stillbirths with anomalies. CONCLUSIONS: Microarray analysis is more likely than karyotype analysis to provide a genetic diagnosis, primarily because of its success with nonviable tissue, and is especially valuable in analyses of stillbirths with congenital anomalies or in cases in which karyotype results cannot be obtained. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development.).

Evaluation of patient education materials: the example of circulating cell free DNA testing for aneuploidy.

Informed consent is the process by which the treating health care provider discloses appropriate information to a competent patient so that the patient may make a voluntary choice to accept or refuse treatment. When the analysis of circulating cell free DNA (ccfDNA) became commercially available in 2011 through the Prenatal Diagnostic Laboratory at Women & Infants Hospital of Providence, Rhode Island to "high-risk" women, it provided an opportunity to examine how commercial laboratories informed potential consumers. We identified, via an internet search, four laboratories offering such testing in the United States and one in Europe. We evaluated patient educational materials (PEMs) from each using the Flesch Reading Ease method and a modified version of the Suitability Assessment of Materials (SAM) criteria. Pamphlets were also reviewed for their inclusion of content recommendations from the International Society for Prenatal Diagnosis, the National Society of Genetic Counselors, the American College of Obstetricians and Gynecologists jointly with the Society of Maternal Fetal Medicine, and the American College of Genetics and Genomics. Reading levels were typically high (10th-12th grade). None of the pamphlets met all SAM criteria evaluated nor did any pamphlet include all recommended content items. To comply with readability and content recommendations more closely, Women & Infants Hospital created a new pamphlet to which it applied the same criteria, and also subjected it to focus group assessment. These types of analyses can serve as a model for future evaluations of similar patient educational materials.

Iatrogenic Preterm Premature Rupture of Membranes after Fetoscopic Laser Ablative Surgery.

INTRODUCTION: To describe the incidence and risk factors for iatrogenic premature preterm rupture of membranes (iPPROM) after fetoscopic laser surgery for the twin-to-twin-transfusion syndrome. MATERIALS AND METHODS: This is a retrospective review of all patients who have undergone fetoscopic laser surgery at a single fetal treatment center since 2000. We defined iPPROM as spontaneous rupture of membranes before the onset of labor prior to 34 weeks of gestation. The iPPROM cohort was compared to the cohort without iPPROM for several preoperative, operative, and delivery characteristics. RESULTS: Ninety-two consecutive patients were reviewed. The overall rate of iPPROM was 18.5% (n = 17). The rates of iPPROM within 1 and 4 weeks were 5.4 and 10.9%, respectively. The median interval from surgery to delivery was significantly shorter in the iPPROM group (21 vs. 62 days, p = 0.01). The mean gestational age at delivery (27.0 vs. 31.1 weeks, p = 0.02) was lower in the iPPROM group. No other characteristics studied differed significantly between the groups. DISCUSSION: The incidence of iPPROM was substantially lower than in recent multicenter reports; however, no risk factors of iPPROM could be identified. Whether this is related to variations in surgical or anesthetic management will require further investigation.

Linking topography to tonotopy in the mouse auditory thalamocortical circuit.

The mouse sensory neocortex is reported to lack several hallmark features of topographic organization such as ocular dominance and orientation columns in primary visual cortex or fine-scale tonotopy in primary auditory cortex (AI). Here, we re-examined the question of auditory functional topography by aligning ultra-dense receptive field maps from the auditory cortex and thalamus of the mouse in vivo with the neural circuitry contained in the auditory thalamocortical slice in vitro. We observed precisely organized tonotopic maps of best frequency (BF) in the middle layers of AI and the anterior auditory field as well as in the ventral and medial divisions of the medial geniculate body (MGBv and MGBm, respectively). Tracer injections into distinct zones of the BF map in AI retrogradely labeled topographically organized MGBv projections and weaker, mixed projections from MGBm. Stimulating MGBv along the tonotopic axis in the slice produced an orderly shift of voltage-sensitive dye (VSD) signals along the AI tonotopic axis, demonstrating topography in the mouse thalamocortical circuit that is preserved in the slice. However, compared with BF maps of neuronal spiking activity, the topographic order of subthreshold VSD maps was reduced in layer IV and even further degraded in layer II/III. Therefore, the precision of AI topography varies according to the source and layer of the mapping signal. Our findings further bridge the gap between in vivo and in vitro approaches for the detailed cellular study of auditory thalamocortical circuit organization and plasticity in the genetically tractable mouse model.

Influence of experience, case load, and stage distribution on outcome of endoscopic laser surgery for TTTS--a review.

OBJECTIVE: Survival (> or =1 twin) after laser surgery for patients with twin-to-twin transfusion syndrome (TTTS) ranges from 65 to 93%. However, most studies are noncontrolled and retrospective, and have included a limited number of patients. The aim of this study was to perform a systematic review of outcomes after laser surgery in patients with TTTS. METHODS: We conducted database and manual searches of reference lists and pertinent journals published between 1995 and 2009 that report outcomes of laser surgery in patients with TTTS. Two authors performed the search independently of each other. There exist only two randomized controlled trials, each with fewer than 80 patients having undergone laser surgery. Uncontrolled and retrospective series were therefore considered as well. Studies had to report sufficient information on inclusive dates, stage distribution, overall neonatal survival, and neonatal survival of at least one twin. Of the 486 studies identified, we considered 19 studies. RESULTS: For each series, 95% confidence intervals (CI) were calculated. Survival was plotted against the date of publication, number of patients/series, gestational age at delivery, and proportion of advanced cases. Univariate analysis was performed to detect significant differences. Our meta-analysis, which included 1484 patients, shows 81.2% survival of at least one twin (CI: 79.1-83.2%). The average survival of at least one twin for the entire population remained within the CI of all but one series. Neither case load, nor stage distribution, nor chronological date of the study affected the survival. CONCLUSION: A systematic review of endoscopic laser surgery performed in patients with TTTS failed to show a significant impact of high caseloads, disease severity distribution, or improvements in technique.

MFM/geneticist view on prenatal management of twins.

Twin pregnancies are associated with an increase in both fetal and maternal morbidity and mortality. Health care supervision is complex, increasingly requiring care from maternal-fetal medicine specialists. This review discusses optimal twin prenatal management, which includes recognizing increased twin pregnancy risks specific to twin-types; counseling families regarding fetal complications, ranging from prematurity to cerebral palsy; screening for aneuploidy and open neural tube defects; specific twin guidelines for diagnostic testing, including chorionic villus sampling and amniocentesis; and monitoring for maternal complications.

The pediatric surgeons' contribution to in utero treatment of twin-to-twin transfusion syndrome.

OBJECTIVE: To evaluate the outcome of twin-to-twin transfusion syndrome (TTTS) treated using a combination of endoscopic fetal surgery-specific techniques and surgical restraint. SUMMARY BACKGROUND DATA: TTTS is a condition of identical twins that, if progressive and left untreated, leads to 100% mortality. The best treatment option is obliteration of the intertwin placental anastomoses, but fetal surgery carries significant maternal and fetal risks. Even if successful, percutaneous endoscopic laser ablation of placental vessels (LASER) causes premature rupture of membranes (PROM) in 10% to 20% of pregnancies. Patient selection is particularly critical because the progression of the disease is unpredictable. This has prompted many to intervene early, yielding survival rates of >=1 twin of 75% to 80%. METHODS: We developed a minimally invasive approach to fetal surgery, a unique membrane sealing technique and a conservative algorithm that reserves intervention for severe TTTS. Pregnancies with TTTS (stages I-IV) managed in the last 8 years were reviewed. LASER was offered in stage III/IV only. RESULTS: Ninety-eight cases of TTTS were managed in a pediatric surgery/maternal-fetal medicine collaborative Fetal Treatment Program-39 were observed (40%) and 59 underwent LASER (60%). Survival of >= twin was seen in 82.7%, and overall survival was 69.4%. These survival rates are similar to, or better than, other comparable series with similar stage distribution (low:high stage ratio 1:1) in which all patients underwent LASER. PROM rate was 4%. CONCLUSIONS: Reserving LASER treatment for severe TTTS results in outcomes similar to, or better than, LASER for all stages. Applying fetal surgery-specific endoscopic techniques, including port-site sealing, reduces postoperative complications.

Low fetal fraction of cell-free DNA predicts placental dysfunction and hypertensive disease in pregnancy.

OBJECTIVE: To examine the association of low fetal fraction of cell-free DNA (cfDNA) with placental compromise and adverse perinatal outcomes. MATERIALS AND METHODS: This was a retrospective cohort utilizing a sample of convenience including 639 women undergoing cfDNA screening at our institution from January 2013 to January 2017. Low fetal fraction was defined as less than the 25th percentile. Indicators of placental compromise were examined individually and as a composite outcome, including hypertensive disease of pregnancy, intrauterine growth restriction, abruption, and oligohydramnios. Neonatal outcomes, including preterm delivery, low Apgar scores, and small for gestational age, also were examined. We calculated risk ratios (RR) and 95% confidence intervals (CI). RESULTS: Low fetal fraction was associated with placental compromise (RR 1.6 [CI 1.1-2.2]), hypertensive disease of pregnancy (RR 1.6 [CI 1.003-2.6]), and preeclampsia with severe features (RR 3.3 [CI 1.2-8.9]). Low fetal faction was not associated with preterm delivery, low Apgar scores, or small for gestational age. CONCLUSIONS: Low fetal fraction of cfDNA among asymptomatic women may serve as a predictor of subsequent placental dysfunction and hypertensive disease.

Cell-Free DNA: Screening for Single-Gene Disorders and Determination of Fetal Rhesus D Genotype.

The use of cell-free DNA (cfDNA) for screening and diagnosis of single-gene disorders is an evolving technology, and its application at this time is limited. Invasive testing is currently recommended for the diagnosis of single-gene disorders. The limitations of cfDNA technology are most notable in clinical settings involving X-linked and autosomal recessive conditions, in part because maternal mutant alleles greatly outnumber those of fetal origin. Examples of single-gene disorders for which cfDNA has been used include skeletal dyplasias, cystic fibrosis, congenital adrenal hyperplasia, ß-thalassemia, and muscular dystrophies.

What education, background, and credentials are required to provide genetic counseling?

Technological advances in genetics have resulted in an increase in the number and complexity of screening and diagnostic tests in the prenatal clinical arena. It is critical that patients are provided with appropriate counseling to enable them to make educated decisions. During this workshop session participants discussed the education, background and credentials required to provide counseling regarding prenatal genetic testing options. The participants agreed that prenatal care providers may have limited time and training to adequately address prenatal genetic testing. Telemedicine and online education may help to address this challenge. Workshop participants agreed that educational and certifying organizations should work together to develop standards for the certification and maintenance of certification processes.

How Should Clinicians Counsel a Woman with a Strong Family History of Early-Onset Alzheimer's Disease about Her Pregnancy?

Counseling patients regarding the benefits, harms, and dilemmas of genetic testing is one of the greatest ethical challenges facing reproductive medicine today. With or without test results, clinicians grapple with how to communicate potential genetic risks as patients weigh their reproductive options. Here, we consider a case of a woman with a strong family history of early-onset Alzheimer's disease (EOAD). She is early in her pregnancy and unsure about learning her own genetic status. We address the ethical ramifications of each of her options, which include genetic testing, genetic counseling, and termination versus continuation of the pregnancy. Our analysis foregrounds clinicians' role in helping to ensure autonomous decision making as the patient reflects on these clinical options in light of her goals and values.

The North American Fetal Therapy Network Consensus Statement: prenatal management of uncomplicated monochorionic gestations.

Owing to vascular connections within a single placenta, monochorionic gestations present distinctive prenatal management challenges. Complications that can arise as a result of unbalanced hemodynamic exchange (twin-twin transfusion syndrome and twin anemia polycythemia sequence) and unequal placental sharing (selective fetal growth restriction) should be kept in mind while prenatal management is being planned. Because of unique monochorionic angioarchitecture, what happens to one twin can directly affect the other. Death of one twin can result in death or permanent disability of the co-twin. Early detection of these unique disease processes through frequent ultrasonographic surveillance may allow the opportunity for earlier referral, intervention, or both and potentially better outcomes. Therefore, monochorionic gestations should be managed differently than dichorionic gestations or singletons. The purpose of this document is to present in detail methods for monitoring and management of uncomplicated monochorionic gestations and to review the evidence for the roles of these methods for detection of complications in clinical practice. Finally, we present evidence-based and expert opinion-supported recommendations developed by the North American Fetal Therapy Network for the diagnosis, surveillance, and delivery of uncomplicated monochorionic gestations.

The North American Fetal Therapy Network consensus statement: prenatal surveillance of uncomplicated monochorionic gestations.

Because they share a common placenta, monochorionic gestations are subject to unique pregnancy complications that can threaten the life and health of both fetuses and therefore impose a disproportionate disease burden on overall perinatal morbidity and mortality. Early detection of these unique disease processes may allow for prompt referral to a regional treatment center, comprehensive counseling, and better patient outcomes. The North American Fetal Therapy Network is a consortium of 30 medical institutions in the United States and Canada with established expertise in fetal surgery and other forms of multidisciplinary care for complex fetal disorders. The goal of this publication is to briefly describe complications of monochorionic gestations and to provide multidisciplinary, evidence-based, and consensus-driven recommendations for surveillance of uncomplicated monochorionic gestations.

Noninvasive prenatal testing for microdeletion syndromes and expanded trisomies: proceed with caution.

The identification of circulating cell-free fetal DNA in maternal plasma has led to the introduction of noninvasive prenatal tests with high sensitivity and high specificity for common aneuploidies (trisomy 13, trisomy 18, trisomy 21). A new expanded noninvasive prenatal testing panel that includes five microdeletion syndromes (22q11 deletion syndrome, cri-du-chat [5p minus], Prader Willi or Angelman syndrome, 1p36 deletion syndrome) and two aneuploidies usually associated with nonviable pregnancies (trisomy 16 and trisomy 22) is now available. This expanded panel will be performed unless an opt-out box is checked. Because these disorders are so rare, the positive predictive value is expected to be low. As with all new screening tests and technologies, the expanded panel should be appropriately studied before it is widely adopted.

Maternal plasma DNA testing: experience of women counseled at a prenatal diagnosis center.

AIMS: To evaluate the early introduction of circulating cell-free (ccf) DNA testing in a prenatal diagnosis center serving a statewide population. RESULTS: A retrospective chart review of patients at high aneuploidy risk counseled during the two 10-week periods that documents indication, risk, maternal age, insurance coverage, decisions, and reasoning behind that decision. Among the 299 included women, indication was advanced maternal age (17% with and 56% without an additional indication), positive serum screen (15%), and abnormal ultrasound (12%). Uptake increased from 10% to 17%, as did patient awareness of the test (4% to 14%). Women with lower copayments were more likely to complete testing (23% vs. 5%, p<0.001). Most women completing testing (75%) wanted to avoid an invasive procedure, while those declining cited testing would not change anything (47%), preferred diagnostic testing (16%), negative follow-up testing (20%), and cost/insurance issues (9%). One of 42 tests was positive (trisomy 21). CONCLUSIONS: Individual patient follow-up allows us to document ccfDNA-related patient decision-making. Nearly half of the women did not want further testing and one in seven preferred immediate diagnostic testing. Patient costs were a barrier to testing that, if avoided, could increase test uptake by 50% or more.

Maternal and fetal safety of fluid-restrictive general anesthesia for endoscopic fetal surgery in monochorionic twin gestations.

STUDY OBJECTIVE: To review our experience with general anesthesia in endoscopic fetal surgery for twin-to-twin transfusion syndrome (TTTS), and to compare fetomaternal outcome before and after protocol implementation. DESIGN: Retrospective impact study. SETTING: University-affiliated medical center. MEASUREMENTS: Data from 85 consecutive patients who underwent endoscopic laser ablation of placenta vessels for severe TTTS were studied. Outcomes were compared in patients before (2000-2007) and after (2008-2012) a change to strict intraoperative intravenous (IV) fluid and liberal vasopressor management. Perioperative parameters (IV fluid administration, vasopressor use, maternal hemoglobin [Hb] concentration); maternal complication rate (respiratory, hemorrhagic); pregnancy outcome; and fetal and neonatal survival were recorded. MAIN RESULTS: Patients in the early group (2000-2007; n = 55) received 1634 ± 949 mL of crystalloid fluid intraoperatively, compared with 485 ± 238 mL (P < 0.001; Student's t test) given to the late group (2008-2012; n = 30). Maternal pulmonary edema and any respiratory distress were seen in 5.5% and 12.7% of patients in the early group, respectively, and in none of the late group patients (P < 0.05; Chi-square analysis). CONCLUSIONS: A significant risk of maternal respiratory complications exists after general anesthesia for endoscopic fetal surgery. Judicious fluid management significantly decreases this risk.