Development of a prenatal clinical care pathway for uncomplicated gastroschisis and literature review.

BACKGROUND: Gastroschisis is an abdominal wall defect wherein the bowel is herniated into the amniotic fluid. Controversy exists regarding optimal prenatal surveillance strategies that predict fetal well-being and help guide timing of delivery. Our objective was to develop a clinical care pathway for prenatal management of uncomplicated gastroschisis at our institution. METHODS: We performed a review of literature from January 1996 to May 2017 to evaluate prenatal ultrasound (US) markers and surveillance strategies that help determine timing of delivery and optimize outcomes in fetal gastroschisis. RESULTS: A total 63 relevant articles were identified. We found that among the US markers, intraabdominal bowel dilatation, polyhydramnios, and gastric dilatation are potentially associated with postnatal complications. Prenatal surveillance strategy with monthly US starting at 28weeks of gestational age (wGA) and twice weekly non-stress testing beginning at 32wGA is recommended to optimize fetal wellbeing. Timing of delivery should be based on obstetric indications and elective preterm delivery prior to 37wGA is not indicated. CONCLUSIONS: Close prenatal surveillance of fetal gastroschisis is necessary due to the high risk for adverse outcomes including intrauterine fetal demise in the third trimester. Decisions regarding the timing of delivery should take into consideration the additional prematurity-associated morbidity.

High-resolution profiling of human cytomegalovirus cell-free DNA in human plasma highlights its exceptionally fragmented nature.

Human cytomegalovirus (CMV) infections comprise a leading cause of newborn impairments worldwide and are pervasive concerns among the immunocompromised. Quantification of CMV viral loads is increasingly used to guide definitions of CMV disease but standardization of CMV quantitation remains problematic, mostly due to differences in qPCR amplicon sizes between clinical laboratories. Here, we used plasma cfDNA sequencing data from 2,208 samples sent for non-invasive prenatal aneuploidy screening to detect CMV and precisely measure the length of CMV fragments in human plasma. CMV reads were identified in 120 (5.4%) samples. Median cfDNA fragment size derived from CMV was significantly shorter than cfDNA derived from human chromosomes (103 vs 172 bp, p < 0.0001), corresponding to the 3rd percentile of human cfDNA. Sequencing of cfDNA from seven plasma samples from transplant patients positive for CMV confirmed the extraordinarily short nature of CMV cfDNA fragment size with a median length of 149 bp. We further show that these high-resolution measurements of CMV DNA fragment size accurately predict measured discrepancies in serum viral load measurements by different qPCR assays. These results highlight the exceptionally fragmented nature of CMV cfDNA and illustrate the promise of plasma cfDNA sequencing for quantitating viral loads through detection of fragments that would be unrecoverable by qPCR.

A Paradigm Shift: Considerations in Prenatal Cell-Free DNA Screening.

BACKGROUND: Testing to determine the health of a fetus has undergone multiple iterations since the widespread adoption of amniocentesis in the 1970s, including several combinations of ultrasound and/or maternal serum screening. The clinical paradigm for prenatal screening for fetal chromosome aneuploidies was transformed by the introduction of cell-free DNA (cfDNA) screening or noninvasive prenatal screening in 2011. CONTENT: The clinical performance of cfDNA screening is well-established for the most common autosomal and sex chromosome aneuploidies with a detection rate exceeding 90% for all aneuploidies. One of the most significant advantages of cfDNA screening relative to maternal serum screening is the markedly reduced false-positive rate, which is <0.5%. The clinical implementation of cfDNA screening is discussed at length, including key biological, preanalytical, and analytical factors that affect test performance. SUMMARY: cfDNA prenatal screening for whole chromosome aneuploidies has become routine in high-risk obstetric populations. There is tremendous interest in expanding cfDNA screening to the general obstetric population. Early studies suggest that routine application of cfDNA screening is both feasible and effective, although significant economic and quality control considerations remain.

Positive predictive value of non-invasive prenatal screening for fetal chromosome disorders using cell-free DNA in maternal serum: independent clinical experience of a tertiary referral center.

BACKGROUND: Non-invasive prenatal screening (NIPS) for fetal chromosome abnormalities using cell-free deoxyribonucleic acid (cfDNA) in maternal serum has significantly influenced prenatal diagnosis of fetal aneuploidies since becoming clinically available in the fall of 2011. High sensitivity and specificity have been reported in multiple publications, nearly all of which have been sponsored by the commercial performing laboratories. Once results are returned, positive and negative predictive values (PPVs, NPVs) are the performance metrics most relevant to clinical management. The purpose of this report is to present independent data on the PPVs of NIPS in actual clinical practice. METHODS: Charts were retrospectively reviewed for patients who had NIPS and were seen March 2012 to December 2013 in a tertiary academic referral center. NIPS results were compared to diagnostic genetic test results, fetal ultrasound results, and clinical phenotype/outcomes. The PPV was calculated using standard epidemiological methods. Correlation between screen results and both maternal age at delivery and gestational age at time of screening was assessed using Wilcoxon's rank sum test. RESULTS: Of 632 patients undergoing NIPS, 92 % of tests were performed in one of the four major commercial laboratories offering testing. However, all four laboratories are represented in both the normal and abnormal results groups. There were 55 abnormal NIPS results. Forty-one of 55 abnormal NIPS results were concordant with abnormal fetal outcomes, 12 were discordant, and 2 were undetermined. The PPV for all conditions included in the screen was 77.4 % (95 % CI, 63.4 - 87.3). Of 578 patients with normal NIPS results, normal pregnancy outcome was confirmed for 156 (27 %) patients. This incomplete follow-up of normal NIPS results does not affect PPV calculations, but it did preclude calculations of sensitivity, specificity, and NPV. Maternal age at delivery was significantly lower for patients with abnormal discordant results, compared to patients with abnormal concordant results (P = 0.034). Gestational age at time of screening was not associated with concordance of screen results (P = 0.722). CONCLUSIONS: The experience of using NIPS in clinical practice confirms that abnormal results cannot be considered diagnostic. Pre-test counseling should emphasize this. Diagnostic genetic testing should always be offered following abnormal NIPS results.

Successful pregnancy in patients with exstrophy-epispadias complex: A University of Washington experience.

INTRODUCTION: With advances in genitourinary reconstructive surgery, women with exstrophy-epispadias complex (EEC) have improved health and quality of life, and may reach reproductive age and consider pregnancy. Despite literature suggesting impaired fertility and higher risk with pregnancy, childbirth is possible. Medical comorbidities, including müllerian anomalies, contribute to increased risk of obstetric and urologic complications during pregnancy. OBJECTIVES: We reviewed our experience with EEC patients who achieved pregnancy to investigate (1) urological characteristics of women who achieved pregnancy; (2) pregnancy management, complications, and delivery; and (3) neonatal outcomes. We developed recommendations for managing pregnancy in women with EEC. STUDY DESIGN/RESULTS: This was a retrospective chart review of 36 female patients with EEC seen at our institution between 1996 and 2013. Female patients less than 18 years, and patients who did not have documented pregnancy were excluded. This resulted in a total of 12 patients with 22 pregnancies. All women with successful pregnancy had bladder exstrophy. The majority had undergone prior bladder augmentation (75%) and were on self-catheterization programs (92%). Thirty-six percent had symptomatic urinary tract infections (UTIs) during pregnancy. Five women had more than one pregnancy. There were four terminations of pregnancy. Of 18 desired pregnancies, there were four spontaneous abortions (SABs) (22%) and 16 live births (78%). The cesarean delivery (CD) rate was 100% (14/14), of which the majority were vertical (classical) uterine incisions with a paramedian skin incision. With the exception of one patient, there were no CD surgical complications. The mean gestational age at delivery was 36 weeks (Range 25 4/7 to 39 4/7 weeks) among eight pregnancies with known gestational age. There were no stillbirths, one neonatal death and no birth defects. DISCUSSION: Women with EEC can have successful pregnancies, though at increased risk for preterm delivery and SABs. In our cohort, the rate of SAB is similar to that described in prior studies. Symptomatic UTIs likely due to self-catheterization were common. Cesarean delivery using a paramedian skin incision and classical uterine incision were not associated with major complications in this cohort. Limitations include reliance on retrospective data and small sample size. The strength of this study is the longitudinal detailed management of pregnancies in EEC women by a single team over time. A multidisciplinary approach to providing a continuum of care from pediatrics through adolescence to adulthood optimizes successful transitions, reproductive health, and successful pregnancies. Based on our experience, an algorithm providing guidance for pregnancy management was developed.

Ambiguous genitalia: what prenatal genetic testing is practical?

Concern for ambiguous genitalia or chromosome-phenotype discordance detected in a prenatal setting has increased over the last two decades. Practitioners faced with this prenatal finding have a variety of genetic tests available to them; however, it is unclear to what extent prenatal testing for disorders of sex development (DSD) is useful or practical. We undertook a retrospective review of the medical records of 140 individuals evaluated through the DSD clinic at Seattle Children's Hospital with birthdates from 01/01/1994 through 08/16/2011 to determine the rate of prenatal detection of ambiguous genitalia in individuals with DSD, what prenatal diagnostic workup was undertaken, and the postnatal outcome, including whether a postnatal genetic diagnosis was confirmed. Of all 140 subjects, 34 (24%) were identified prenatally. The most common postnatal diagnoses were penoscrotal hypospadias with transposition of the scrotum with no known genetic cause (24/140; 17%) and 21-hydroxylase deficiency (20/140; 14%). Apart from these, no single diagnosis comprised more than a few cases. Prenatal diagnostic testing varied widely, from no tests to multiple molecular tests with amniotic fluid hormone concentrations. In the absence of other fetal anomalies or growth retardation on ultrasound, prenatal karyotype with fluorescence in situ hybridization for the SRY gene is the most useful test when ambiguous genitalia is suspected. Further prenatal testing for Smith-Lemli-Opitz syndrome in 46,XY individuals and congenital adrenal hyperplasia in 46,XX individuals may be considered. However, targeted molecular testing for rare DSD conditions in the absence of a family history of DSD has a low yield.

Clinical, neuroradiological and genetic findings in pontocerebellar hypoplasia.

Pontocerebellar hypoplasia is a group of autosomal recessive neurodegenerative disorders with prenatal onset. The common characteristics are cerebellar hypoplasia with variable atrophy of the cerebellum and the ventral pons. Supratentorial involvement is reflected by variable neocortical atrophy, ventriculomegaly and microcephaly. Mutations in the transfer RNA splicing endonuclease subunit genes (TSEN54, TSEN2, TSEN34) were found to be associated with pontocerebellar hypoplasia types 2 and 4. Mutations in the mitochondrial transfer RNA arginyl synthetase gene (RARS2) were associated with pontocerebellar hypoplasia type 6. We studied a cohort of 169 patients from 141 families for mutations in these genes, of whom 106 patients tested positive for mutations in one of the TSEN genes or the RARS2 gene. In order to delineate the neuroradiological and clinical phenotype of patients with mutations in these genes, we compared this group with 63 patients suspected of pontocerebellar hypoplasia who were negative on mutation analysis. We found a strong correlation (P < 0.0005) between TSEN54 mutations and a dragonfly-like cerebellar pattern on magnetic resonance imaging, in which the cerebellar hemispheres are flat and severely reduced in size and the vermis is relatively spared. Mutations in TSEN54 are clinically associated with dyskinesia and/or dystonia and variable degrees of spasticity, in some cases with pure generalized spasticity. Nonsense or splice site mutations in TSEN54 are associated with a more severe phenotype of more perinatal symptoms, ventilator dependency and early death. In addition, we present ten new mutations in TSEN54, TSEN2 and RARS2. Furthermore, we show that pontocerebellar hypoplasia type 1 together with elevated cerebrospinal fluid lactate may be caused by RARS2 mutations.

Meiotic recombination in human oocytes.

Studies of human trisomies indicate a remarkable relationship between abnormal meiotic recombination and subsequent nondisjunction at maternal meiosis I or II. Specifically, failure to recombine or recombination events located either too near to or too far from the centromere have been linked to the origin of human trisomies. It should be possible to identify these abnormal crossover configurations by using immunofluorescence methodology to directly examine the meiotic recombination process in the human female. Accordingly, we initiated studies of crossover-associated proteins (e.g., MLH1) in human fetal oocytes to analyze their number and distribution on nondisjunction-prone human chromosomes and, more generally, to characterize genome-wide levels of recombination in the human female. Our analyses indicate that the number of MLH1 foci is lower than predicted from genetic linkage analysis, but its localization pattern conforms to that expected for a crossover-associated protein. In studies of individual chromosomes, our observations provide evidence for the presence of "vulnerable" crossover configurations in the fetal oocyte, consistent with the idea that these are subsequently translated into nondisjunctional events in the adult oocyte.

Aggressive prenatal care results in successful fetal outcomes in CF women.

BACKGROUND: The impact of pre-pregnancy pulmonary and nutritional status in pregnancy outcomes of women with cystic fibrosis (CF) is not clearly defined. METHODS: A chart review of CF women who attended the University of Washington Medical Center (UWMC), Seattle WA. from January 1989 until May 2004. RESULTS: There were 43 pregnancies resulting in 36 live births among 25 of 189 CF women. In the subset of CF women receiving their obstetric care at the UWMC whose FEV1 was < 50% predicted, infant weight was lower than in women with a higher FEV1 (2.9 kg+/-0.4 (range 2.2-3.3 kg) versus 3.4+/-0.8 kg (range 2.5-5.1 kg)) p = 0.05 although the gestational ages were the same (37+/-2 weeks (range 33-39 weeks) versus to 38+/-2 weeks (range 35-40 weeks) p = 0.17). Infant weight and gestational age of women whose initial BMI was < 20 kg/m2 was no different from women with a normal initial BMI (3.0+/-0.4 kg, range 2.2-3.4 kg versus 3.3+/-0.8 kg, range 2.6-5.1 kg p = 0.29, and 37.7+/-2.4 weeks, range 33-39 weeks versus 37.2+/-2.1 weeks, range 34-40 weeks). CONCLUSIONS: CF women with severe pulmonary impairment tend to have lower weight babies but it remains difficult to determine prospectively which CF women will tolerate pregnancy well. Aggressive antepartum management is recommended for all CF women.

The synaptonemal complex and meiotic recombination in humans: new approaches to old questions.

Meiotic prophase serves as an arena for the interplay of two important cellular activities, meiotic recombination and synapsis of homologous chromosomes. Synapsis is mediated by the synaptonemal complex (SC), originally characterized as a structure linked to pairing of meiotic chromosomes (Moses (1958) J Biophys Biochem Cytol 4:633-638). In 1975, the first electron micrographs of human pachytene stage SCs were presented (Moses et al. (1975) Science 187:363-365) and over the next 15 years the importance of the SC to normal meiotic progression in human males and females was established (Jhanwar and Chaganti (1980) Hum Genet 54:405-408; Pathak and Elder (1980) Hum Genet 54:171-175; Solari (1980) Chromosoma 81:315-337; Speed (1984) Hum Genet 66:176-180; Wallace and Hulten (1985) Ann Hum Genet 49(Pt 3):215-226). Further, these studies made it clear that abnormalities in the assembly or maintenance of the SC were an important contributor to human infertility (Chaganti et al. (1980) Am J Hum Genet 32:833-848; Vidal et al. (1982) Hum Genet 60:301-304; Bojko (1983) Carlsberg Res Commun 48:285-305; Bojko (1985) Carlsberg Res Commun 50:43-72; Templado et al. (1984) Hum Genet 67:162-165; Navarro et al. (1986) Hum Reprod 1:523-527; Garcia et al. (1989) Hum Genet 2:147-53). However, the utility of these early studies was limited by lack of information on the structural composition of the SC and the identity of other SC-associated proteins. Fortunately, studies of the past 15 years have gone a long way toward remedying this problem. In this minireview, we highlight the most important of these advances as they pertain to human meiosis, focusing on temporal aspects of SC assembly, the relationship between the SC and meiotic recombination, and the contribution of SC abnormalities to human infertility.

FISHing for acrocentric associations between chromosomes 14 and 21 in human oogenesis.

OBJECTIVE: The purpose of this study was to search for cytologic evidence of robertsonian translocation formation that involves chromosomes 14q and 21q in human oogenesis with the use of dual color fluorescent in situ hybridization with whole chromosome paints. STUDY DESIGN: The oocytes from a chromosomally normal fetus at 23.5 weeks of gestation underwent cohybridization with chromosome specific DNA libraries from chromosomes 14 and 21. The nuclei were scored for the proportion of meiosis I prophase substages and for hybridization efficiency and were evaluated for the presence of hybridization signals that were suggestive of heterologous associations between chromosomes 14q and 21q in zygotene, pachytene, and diplotene. RESULTS: A total of 1769 meiotic nuclei were analyzed. Of 272 informative nuclei at zygotene, pachytene, and diplotene, 1 nucleus at pachytene demonstrated hybridization signals for chromosomes 14 and 21 that could be consistent with a robertsonian translocation. CONCLUSION: A heterologous association between chromosomes 14q and 21q that possibly represent robertsonian translocation formation was observed cytologically with the use of fluorescent in situ hybridization.