Lisa Hui

Congenital cytomegalovirus infection in pregnancy and the neonate: consensus recommendations for prevention, diagnosis, and therapy

Congenital cytomegalovirus is the most frequent, yet under-recognised, infectious cause of newborn malformation in developed countries. Despite its clinical and public health importance, questions remain regarding the best diagnostic methods for identifying maternal and neonatal infection, and regarding optimal prevention and therapeutic strategies for infected mothers and neonates. The absence of guidelines impairs global efforts to decrease the effect of congenital cytomegalovirus. Data in the literature suggest that congenital cytomegalovirus infection remains a research priority, but data are yet to be translated into clinical practice. An informal International Congenital Cytomegalovirus Recommendations Group was convened in 2015 to address these questions and to provide recommendations for prevention, diagnosis, and treatment. On the basis of consensus discussions and a review of the literature, we do not support universal screening of mothers and the routine use of cytomegalovirus immunoglobulin for prophylaxis or treatment of infected mothers. However, treatment guidelines for infected neonates were recommended. Consideration must be given to universal neonatal screening for cytomegalovirus to facilitate early detection and intervention for sensorineural hearing loss and developmental delay, where appropriate. The group agreed that education and prevention strategies for mothers were beneficial, and that recommendations will need continual updating as further data become available.

Recent advances in the prenatal interrogation of the human fetal genome

The amount of genetic and genomic information obtainable from the human fetus during pregnancy is accelerating at an unprecedented rate. Two themes have dominated recent technological advances in prenatal diagnosis: interrogation of the fetal genome in increasingly high resolution and the development of non-invasive methods of fetal testing using cell-free DNA in maternal plasma. These two areas of advancement have now converged with several recent reports of non-invasive assessment of the entire fetal genome from maternal blood. However, technological progress is outpacing the ability of the healthcare providers and patients to incorporate these new tests into existing clinical care, and further complicates many of the economic and ethical dilemmas in prenatal diagnosis. This review summarizes recent work in this field and discusses the integration of these new technologies into the clinic and society.

The amniotic fluid transcriptome: a source of novel information about human fetal development.

OBJECTIVE: Amniotic fluid is a complex biological material that provides a unique window into the developing human. Residual amniotic fluid supernatant contains cell-free fetal RNA. The objective of this study was to develop an understanding of the amniotic fluid core transcriptome by analyzing the transcripts ubiquitously present in the amniotic fluid supernatant of euploid midtrimester fetuses. METHODS: This was an in silico (computational) investigation using publicly available gene expression data previously produced by our group from 12 euploid midtrimester amniotic fluid samples. Functional analyses were performed using a web-based software analysis tool. Organ specificity was examined for each transcript using a gene expression atlas. For fetal organs not represented in the atlas, manual literature searching and the web-based software analysis tool were used to generate fetal organ-associated gene lists. RESULTS: There were 476 well-annotated genes present in 12 of 12 amniotic fluid samples. Functional analysis identified six physiologic systems represented in the amniotic fluid core transcriptome, including musculoskeletal and nervous system development and function and embryonic and organismal development. Mammalian target of rapamycin signaling was identified as a key canonical pathway. Twenty-three highly organ-specific transcripts were identified; six of these are known to be highly expressed in the fetal brain. CONCLUSION: Amniotic fluid cell–free fetal RNA can provide biological information on multiple fetal organ systems. The presence of fetal-brain specific transcripts in amniotic fluid suggests novel approaches to the study of developmental disorders that involve the central nervous system. The finding that the mammalian target of rapamycin signaling is enriched in midtrimester fetuses may have future applications in the study of fetal growth disorders. LEVEL OF EVIDENCE: III

Perinatal outcome after maternal primary cytomegalovirus infection in the first trimester: a practical update and counseling aid

Cytomegalovirus (CMV) is the most common cause of congenital infection with approximately 0.5% of pregnant women in developed countries seroconverting during pregnancy. In utero transmission occurs in about one third of women who develop primary infection in the first trimester, and these fetuses are at risk for adverse perinatal outcomes and long‐term neurological complications. The great promise of a prenatal therapy to reduce fetal infection after maternal primary CMV infection has not been realized to date. The prediction of CMV sequelae is particularly challenging for clinicians because of the heterogeneity of the published literature, the wide spectrum of perinatal outcomes, the adjustment of fetal risk at each stage of assessment, and the variable quality of published data. Given the continued lack of a proven fetal therapy, it is timely to review the natural history of congenital CMV in the modern management era. We have analyzed the recent literature, integrated findings from multiple studies, and calculated stage‐specific risks for adverse perinatal outcome to assist in counseling women with first trimester primary CMV infection.

Noninvasive prenatal testing for trisomy 21: Challenges for implementation in Australia

The term ‘Non invasive prenatal testing’ is used to describe the rapidly emerging molecular technologies related to cell free DNA assessment that are being applied to prenatal screening for Down syndrome and other chromosomal abnormalities. This technology is now available to Australian women through a number of off‐shore laboratories. We review the basis of this method of testing, the literature describing the effectiveness of NIPT in screening for trisomy 21 and the potential methods by which this tool could be incorporated into current screening strategies.

Population‐based trends in prenatal screening and diagnosis for aneuploidy: a retrospective analysis of 38 years of state‐wide data

To analyse population‐based trends over the entire history of prenatal testing for aneuploidy.

Maternal Obesity Affects Fetal Neurodevelopmental and Metabolic Gene Expression: A Pilot Study

Objective One in three pregnant women in the United States is obese. Their offspring are at increased risk for neurodevelopmental and metabolic morbidity. Underlying molecular mechanisms are poorly understood. We performed a global gene expression analysis of mid-trimester amniotic fluid cell-free fetal RNA in obese versus lean pregnant women. Methods This prospective pilot study included eight obese (BMI≥30) and eight lean (BMI<25) women undergoing clinically indicated mid-trimester genetic amniocentesis. Subjects were matched for gestational age and fetal sex. Fetuses with abnormal karyotype or structural anomalies were excluded. Cell-free fetal RNA was extracted from amniotic fluid and hybridized to whole genome expression arrays. Genes significantly differentially regulated in 8/8 obese-lean pairs were identified using paired t-tests with the Benjamini-Hochberg correction (false discovery rate of <0.05). Biological interpretation was performed with Ingenuity Pathway Analysis and the BioGPS gene expression atlas. Results In fetuses of obese pregnant women, 205 genes were significantly differentially regulated. Apolipoprotein D, a gene highly expressed in the central nervous system and integral to lipid regulation, was the most up-regulated gene (9-fold). Apoptotic cell death was significantly down-regulated, particularly within nervous system pathways involving the cerebral cortex. Activation of the transcriptional regulators estrogen receptor, FOS, and STAT3 was predicted in fetuses of obese women, suggesting a pro-estrogenic, pro-inflammatory milieu. Conclusion Maternal obesity affects fetal neurodevelopmental and metabolic gene expression as early as the second trimester. These findings may have implications for postnatal neurodevelopmental and metabolic abnormalities described in the offspring of obese women.

Novel neurodevelopmental information revealed in amniotic fluid supernatant transcripts from fetuses with trisomies 18 and 21

Trisomies 18 and 21 are the two most common live born autosomal aneuploidies in humans. While the anatomic abnormalities in affected fetuses are well documented, the dysregulated biological pathways associated with the development of the aneuploid phenotype are less clear. Amniotic fluid (AF) cell-free RNA is a valuable source of biological information obtainable from live fetuses. In this study, we mined gene expression data previously produced by our group from mid-trimester AF supernatant samples. We identified the euploid, trisomy 18 and trisomy 21 AF transcriptomes, and analyzed them with a particular focus on the nervous system. We used multiple bioinformatics resources, including DAVID, Ingenuity Pathway Analysis, and the BioGPS Gene Expression Atlas. Our analyses confirmed that AF supernatant from aneuploid fetuses is enriched for nervous system gene expression and neurological disease pathways. Tissue analysis showed that fetal brain cortex and Cajal–Retzius cells were significantly enriched for genes contained in the AF transcriptomes. We also examined AF transcripts known to be dysregulated in aneuploid fetuses compared with euploid controls and identified several brain-specific transcripts among them. Many of these genes play critical roles in nervous system development. NEUROD2, which was downregulated in trisomy 18, induces neurogenic differentiation. SOX11, downregulated in trisomy 21, is a transcription factor that is essential for pan-neuronal protein expression and axonal growth of sensory neurons. Our results show that whole transcriptome analysis of cell-free RNA in AF from live pregnancies permits discovery of biomarkers of abnormal human neurodevelopment and advances our understanding of the pathophysiology of aneuploidy.

Clinical implementation of cell‐free DNA‐based aneuploidy screening: perspectives from a national audit

In late 2011, a prenatal screening test for fetal chromosomal abnormalities using cell-free DNA in maternal plasma was introduced commercially in the USA. This next-generation sequencing-based method, commonly referred to as non-invasive prenatal testing (NIPT), represented the most accurate form of screening for trisomy 21 to date1. While the NIPT market expanded rapidly in the USA, its clinical implementation in other developed countries varied considerably due to local factors, such as existing care models, insurance coverage and legal restrictions. In late 2012, NIPT became available clinically in Australia, through overseas laboratories, 1 year after it did in the USA. By the end of 2013, there were five providers in the Australian market offering NIPT on a self-funded basis. Australian subspecialists in maternal–fetal medicine and obstetric ultrasound quickly became the major sources of referral for NIPT due to their well-established role in first-trimester screening and prenatal diagnostic procedures. Despite being ‘early adopters’ of technology, Australian sonologists had concerns about NIPT that were common to many countries. Among these were definition of the appropriate indications for use, and the uncertain test-failure rates and turnaround times associated with offshore laboratory processing outside trial conditions. The lack of government regulation and lack of data collection were also key concerns2. At the time, international reports on clinical implementation were either single-center experiences3,4, or multicenter industry-sponsored studies of a single commercial assay5. In response to these issues, a group of Australian obstetric sonologists formed a collaboration to document the collective national experience of NIPT, across a range of practice types and using a variety of NIPT providers.

Non‐invasive prenatal testing for fetal aneuploidy: charting the course from clinical validity to clinical utility

In this issue of the Journal, we see further contributions to the rapidly growing body of literature on non-invasive prenatal testing (NIPT) for fetal aneuploidy using sequencing of maternal plasma DNA. Ashoor et al. provide data on a chromosome-selective method for the non-invasive prenatal detection of trisomy 131 and the effect of fetal fraction on test performance2. These papers join a wave of clinical validation studies published in the past 18 months; since 2011, there have been at least 11 such publications analyzing the test performance of NIPT for aneuploidy in high-risk women1,3–12. It is now established that trisomy 21 can be detected reliably from 10 weeks’ gestation in high-risk singleton pregnancies with superior sensitivity (> 99%) and specificity (false-positive rate < 1%) compared with conventional screening methods (Table 1). Trisomy 18 and 13 are also detectable, but test accuracy is less consistent than that for trisomy 21.