Risk of meningomyelocele mediated by the common 22q11.2 deletion.

Meningomyelocele is one of the most severe forms of neural tube defects (NTDs) and the most frequent structural birth defect of the central nervous system. We assembled the Spina Bifida Sequencing Consortium to identify causes. Exome and genome sequencing of 715 parent-offspring trios identified six patients with chromosomal 22q11.2 deletions, suggesting a 23-fold increased risk compared with the general population. Furthermore, analysis of a separate 22q11.2 deletion cohort suggested a 12- to 15-fold increased NTD risk of meningomyelocele. The loss of Crkl, one of several neural tube-expressed genes within the minimal deletion interval, was sufficient to replicate NTDs in mice, where both penetrance and expressivity were exacerbated by maternal folate deficiency. Thus, the common 22q11.2 deletion confers substantial meningomyelocele risk, which is partially alleviated by folate supplementation.

Identification of a novel LFNG variant in a Chinese fetus with spondylocostal dysostosis and a systematic review.

Spondylocostal dysostosis (SCDO) encompasses a group of skeletal disorders characterized by multiple segmentation defects in the vertebrae and ribs. SCDO has a complex genetic etiology. This study aimed to analyze and identify pathogenic variants in a fetus with SCDO. Copy number variant sequencing and whole exome sequencing were performed on a Chinese fetus with SCDO, followed by bioinformatics analyses, in vitro functional assays and a systematic review on the reported SCDO cases with LFNG pathogenic variants. Ultrasound examinations in utero exhibited that the fetus had vertebral malformation, scoliosis and tethered cord, but rib malformation was not evident. We found a novel homozygous variant (c.1078 C > T, p.R360C) within the last exon of LFNG. The variant was predicted to cause loss of function of LFNG by in silico prediction tools, which was confirmed by an in vitro assay of LFNG enzyme activity. The systematic review listed a total of 20 variants of LFNG in SCDO. The mutational spectrum spans across all exons of LFNG except the last one. This study reported the first Chinese case of LFNG-related SCDO, revealing the prenatal phenotypes and expanding the mutational spectrum of the disorder.

Humoral immune transcriptome signature in myelomeningocele patients.

INTRODUCTION: Myelomeningocele (MMC) results from incomplete closure of the neural tube, and has a complex multifactorial etiology, including an inflammatory microenvironment. OBJECTIVE: We evaluated the contribution of humoral immune response for development of inflammatory milieu. METHODS: Using public repository Gene Expression Omnibus (GEO), we retrieve dataset transcriptome from the amniotic fluid of ten fetuses with myelomeningocele and ten healthy control fetuses to found differential gene expression associated with disturbances and inflammatory signatures in MMC. The identified DEGs were submitted to enrichment, network, and matrix correlation analyses. RESULTS: Our initial analysis revealed 90 DEGs in MMC, mainly associated with signaling pathways of inflammation, including the immune modules, humoral immune response and IFN-type I signatures. Protein-protein analysis (PPI) revealed an association with three protein networks; positive regulation of B cell proliferation constituted the largest network. Matrix correlation analyses showed that MMC alters the co-expression of genes related to inflammatory processes that promote microenvironment inflammation. CONCLUSION: These results revealed an altered humoral immune response in MMC patients, contributing to an inflammatory profile and providing opportunities for identifying potential biomarkers in myelomeningocele disease.

Mutational analysis of FOLR1 and FOLR2 genes in children with Myelomeningocele.

Myelomeningocele (MMC) is a congenital disease. For a long time, molecular mechanism of MMC, the role of folate receptor and transporter proteins remain unclear. Folate from maternal lumen to developing embryo is carried out with the help of folate transporters (SLC46A1, SLC19A1, FOLH1 and SLC25A32) and folate receptor (FOLR1, FOLR2 and FOLR3). Due to the loss of function of these important genes, complications can facilitate the risk of MMC. This study focused on the mutational analysis of FOLR1 and FOLR2 genes in children suffering from MMC. Myelomeningocele is a rare disorder so twenty blood samples from the children were collected. Primers of selected exons for FOLR1 and FOLR2 genes were designed with the help of PrimerFox software. Extracted DNA was amplified, and PCR based mutational analysis was done to check any type of mutation/SNPs in these genes. Sanger sequencing method was performed to confirm mutation in FOLR1 and FOLR2 genes. The results showed that certain environmental factors (smoking, low socio-economic status of mother bearing MMC fetus) were found to be significantly (P<0.05) associated with MMC but no mutation in the selected exons of FOLR1 and FOLR2 genes was detected. Thus, genetic variations in the folate transporter gene may have no role in the progression of MMC in the studied population.

Myelomeningocele among Pakistani population.

OBJECTIVE: To investigate the mutation in Vangl1 gene in patients of myelomeningocele. METHODS: The cross-sectional study was conducted from July 2017 to December 2017 in the Dow Diagnostic and Research Laboratory, Karachi, after approval from the ethics review committee of Dow University of Health Sciences, Karachi, and comprised clinically diagnosed infants and 10 healthy individuals from the outpatient department of Jinnah Postgraduate Medical Centre, Karachi. Several anatomical parameters were considered, such as size and site of the cyst. Blood samples were drawn and polymerase chain reaction was conducted for the identification of mutation in Vangl1 gene. Mutation analysis was carried out by aligning the sequence with the reference sequence. RESULTS: Of the 60 subjects, 50(83.3%) were cases with age range 0-10 years, and 10(16.6%) were age matched controls. Majority of the patients 44 (88%) were aged <1 year. Novel mutation in Vangl1 gene was identified at position 239, showing the substitution of valine with glycineV239G. Lumbar region was the most common site for the presentation of myelomeningocele in most of the patients 46(92%). CONCLUSIONS: The rare mutation of myelomeningocele was found present in the sample, and the disease was found mostly in the lumbar region.

Malformaciones congénitas en recién nacidos hospitalizados en sala de neonatología del hospital nacional Mario Catarino Rivas, 2019 / Congenital malformations in newborns hospitalized in the neonatology ward of the National Hospital Mario Catarino Rivas, 2019

Antecedentes: Las malformaciones congéni- tas han sido un problema de salud pública que afecta a la sociedad y a la familia. Se ha identifica- do ciertas causas de malformaciones congénitas, entre ellas se encuentran las ambientales, genéti- cas; y, multifactoriales. Se estima que un 10% se debe a causas ambientales, 25% a causas genéti- cas y 65% a factores de origen multifactorial. La Organización Mundial de la Salud (OMS) estima que cada año 303,000 recién nacido fallecen du- rante las primeras semanas de vida, secundario a malformaciones congénitas. Objetivo: Descri- bir las características clínicas y antecedentes ma- ternos de los recién nacidos con malformaciones congénitas hospitalizados en la sala de neonato- logía en el Hospital Nacional "Mario Catarino Rivas" en enero a diciembre 2019. Pacientes y Métodos: Se realizó un estudio observacional, descriptivo, retrospectivo, transversal. Se analiza una muestra de 212 pacientes recién nacidos con malformaciones congénitas. Se utilizó estadística descriptiva para la exposición de resultados, se usaron tablas de cotejo en el programa estadísti- co IBM SPSS versión número 25. Resultados: El promedio de edad materna de recién nacidos El sistema circulatorio presentó el mayor nú- mero de malformaciones congénitas con 22,2%. Malformaciones congénitas en recién nacidos hospitalizados en sala de neonatología del hospital nacional Mario Catarino Rivas, 2019 El sistema circulatorio presentó el mayor nú- mero de malformaciones congénitas con 22,2%. Siendo el foramen oval permeable el más fre- cuente en este sistema con 9,4%. El mielomenin- gocele fue la malformación congénita más fre- cuente con 10,4%. Conclusión: La prevalencia de malformaciones congénitas fue de 4.3% sien- do este similar al rango reportado en la literatura internacional. El sistema circulatorio presentó la mayor prevalencia y el foramen oval permeable la malformación congénita más frecuente de este sistema. El Mielomeningocele como la malfor- mación congénita más frecuente en nuestra po- blación...(AU)

Human myelomeningocele risk and ultra-rare deleterious variants in genes associated with cilium, WNT-signaling, ECM, cytoskeleton and cell migration.

Myelomeningocele (MMC) affects one in 1000 newborns annually worldwide and each surviving child faces tremendous lifetime medical and caregiving burdens. Both genetic and environmental factors contribute to disease risk but the mechanism is unclear. This study examined 506 MMC subjects for ultra-rare deleterious variants (URDVs, absent in gnomAD v2.1.1 controls that have Combined Annotation Dependent Depletion score ≥ 20) in candidate genes either known to cause abnormal neural tube closure in animals or previously associated with human MMC in the current study cohort. Approximately 70% of the study subjects carried one to nine URDVs among 302 candidate genes. Half of the study subjects carried heterozygous URDVs in multiple genes involved in the structure and/or function of cilium, cytoskeleton, extracellular matrix, WNT signaling, and/or cell migration. Another 20% of the study subjects carried heterozygous URDVs in candidate genes associated with gene transcription regulation, folate metabolism, or glucose metabolism. Presence of URDVs in the candidate genes involving these biological function groups may elevate the risk of developing myelomeningocele in the study cohort.

Myelomeningocele genotype-phenotype correlation findings in cilia, HH, PCP, and WNT signaling pathways.

BACKGROUND: Myelomeningocele (MMC) is the most severe and frequent type of spina bifida. Its etiology remains poorly understood. The Hedgehog (Hh), Wnt, and planar cell polarity (PCP) signaling pathways are essential for normal tube closure, needing a structural-functional cilium for its adequate function. The present study aimed to investigate the impact of different gene variants (GV) from those pathways on MMC genotype-subphenotype correlations. METHODS: The study comprised 500 MMC trios and 500 controls, from 16 Telethon centers of 16 Mexican states. Thirty-four GVs of 29 genes from cilia, Hh, PCP, and Wnt pathways, were analyzed, by an Illumina on design microarray. The total sample (T-MMC) was stratified in High-MMC (H-MMC) when thoracic and Low-MMC (L-MMC) when lumbar-sacral vertebrae affected. STATA/SE-12.1 and PLINK software were used for allelic association, TDT, and gene-gene interaction (GGI) analyses, considering p value <.01 as statistically significant differences (SSD). RESULTS: Association analysis showed SSD for COBL-rs10230120, DVL2-rs2074216, PLCB4-rs6077510 GVs in T-MMC and L-MMC, and VANGL2-rs120886448 in T-MMC and H-MMC, and INVS-rs7024375 exclusively in L-MMC. TDT assay showed SSD preferential transmissions of C2CD3-rs826058 in H-MMC, and LRP5-rs3736228, and BBS2-rs1373 in L-MMC. Statistically significant GGI was observed in four in T-MMC, four completely different in L-MMC, and one in H-MMC. Interestingly, no one repeated in subphenotypes. CONCLUSIONS: Our results support an association of GVs in Hh, Wnt, PCP, and cilia pathways, with MMC occurrence location, although further validation is needed. Furthermore, present results show a distinctive panel of gene-variants in H-MMC and LMMC subphenotypes, suggesting a feasible genotype-phenotype correlation.

Dual Myelomeningoceles in Twins: Case Report, Review, and Insights for Etiology.

INTRODUCTION: Despite folate supplementation, neural tube defects (NTDs) still occur in 0.5-1.0/1,000 pregnancies, with 30-50% not preventable with folate. Twinning has increased due to artificial fertilization and in itself predisposes to NTDs at a rate of 1.6/1,000. The contributions of genetic and environmental factors to myelomeningocele development remain poorly understood. Expression patterns of congenital pathologies in twins can sometimes provide etiological insight. Concordance of NTDs in twins is 0.03/1,000, with dual myelomeningocele reported in only 23 pairs, only one of which survived. We present the 24th pair, the 1st to maintain lower extremity motor function. We review all prior cases and discuss implications of twin concordance on the interplay of genetic and environmental influences. Case Report and Review: A new case of female monozygotic twins born to a well-nourished 24-year-old female is reported with details of perioperative care. Prenatal ultrasound showed L3-S4 and L5-S4 myelomeningoceles, Chiari II malformations, and ventriculomegaly. Copy number microarray was unrevealing. Each underwent uncomplicated repair on day of life 1, and ventriculoperitoneal shunt placement on days of life 10 and 16. Both had movement in the legs upon 6-week follow-up. All prior reported cases of concordant twin myelomeningoceles were abstracted and analyzed, revealing persistence of occurrence despite folate supplementation and a majority occurring in dizygotic pairs. The literature is also reviewed to summarize current knowledge of myelomeningocele pathophysiology as it relates to genetic and environmental influences. DISCUSSION: Meticulous surgical and perioperative care allowed for early positive outcomes in each twin. However, etiopathogenesis remains elusive. In general, only of a minority of cases have underlying genetic lesions or clear environmental triggers. Concordance in monozygotic twins argues for a strong genetic influence; yet, literature review reveals a higher rate of concordant dizygotic twins. This, along with the observation of differing resultant phenotypes in monozygotic twins as seen in this case, prompts further investigation into nonfolate environmental influences. While efforts in genetic investigation should continue, the role of teratogens and exposures should not be minimized in research efforts, public health, and family counseling. Clinical genetic testing remains of limited utility in the majority of patients until more is known.

Burden of rare deleterious variants in WNT signaling genes among 511 myelomeningocele patients.

Genes in the noncanonical WNT signaling pathway controlling planar cell polarity have been linked to the neural tube defect myelomeningocele. We hypothesized that some genes in the WNT signaling network have a higher mutational burden in myelomeningocele subjects than in reference subjects in gnomAD. Exome sequencing data from 511 myelomeningocele subjects was obtained in-house and data from 29,940 ethnically matched subjects was provided by version 2 of the publicly available Genome Aggregation Database. To compare mutational burden, we collapsed rare deleterious variants across each of 523 human WNT signaling genes in case and reference populations. Ten WNT signaling genes were disrupted with a higher mutational burden among Mexican American myelomeningocele subjects compared to reference subjects (Fishers exact test, P ≤ 0.05) and seven different genes were disrupted among individuals of European ancestry compared to reference subjects. Gene ontology enrichment analyses indicate that genes disrupted only in the Mexican American population play a role in planar cell polarity whereas genes identified in both populations are important for the regulation of canonical WNT signaling. In summary, evidence for WNT signaling genes that may contribute to myelomeningocele in humans is presented and discussed.

Identification of novel candidate risk genes for myelomeningocele within the glucose homeostasis/oxidative stress and folate/one-carbon metabolism networks.

BACKGROUND: Neural tube defects (NTDs) are the second most common complex birth defect, yet, our understanding of the genetic contribution to their development remains incomplete. Two environmental factors associated with NTDs are Folate and One Carbon Metabolism (FOCM) and Glucose Homeostasis and Oxidative Stress (GHOS). Utilizing next-generation sequencing of a large patient cohort, we identify novel candidate genes in these two networks to provide insights into NTD mechanisms. METHODS: Exome sequencing (ES) was performed in 511 patients, born with myelomeningocele, divided between European American and Mexican American ethnicities. Healthy control data from the Genome Aggregation database were ethnically matched and used as controls. Rare, high fidelity, nonsynonymous predicted damaging missense, nonsense, or canonical splice site variants in independently generated candidate gene lists for FOCM and GHOS were identified. We used a gene-based collapsing approach to quantify mutational burden in case and controls, with the control cohort estimated using cumulative allele frequencies assuming Hardy-Weinberg equilibrium. RESULTS: We identified 45 of 837 genes in the FOCM network and 22 of 568 genes in the GHOS network as possible NTD risk genes with p < 0.05. No nominally significant risk genes were shared between ethnicities. Using a novel approach to mutational burden we identify 55 novel NTD risk associations. CONCLUSIONS: We provide a means of utilizing large publicly available sequencing datasets as controls for sequencing projects examining rare disease. This approach confirmed existing risk genes for myelomeningocele and identified possible novel risk genes. Lastly, it suggests possible distinct genetic etiologies for this malformation between different ethnicities.

ABO and Rh Blood Groups and Risk of Myelomeningocele.

AIM: To investigate the relationship between the distribution of ABO or Rhesus (Rh) blood group antigens and the incidence of myelomeningocele. MATERIAL AND METHODS: A retrospective data was reviewed for all myelomeningocele patients operated at a tertiary academic hospital between years 2014 and 2019. Age, sex, delivery method, physical and neurological examination findings, and radiological findings alongside with blood type of each patient were recorded. The data of blood group distribution among the study patients was compared to the data of healthy individuals in the same region. RESULTS: Patients with group B and AB showed a higher chance of developing myelomeningocele. Rh-positive blood group was associated with high incidence of myelomeningocele (93.5%), whereas Rh-negative blood group showed least association (6.5%). Rh-positive blood group was also found to be more frequent in patients with myelomeningocele with hydrocephalus and Chiari malformation. CONCLUSION: The findings of this study show that ABO and Rh blood groups have an effect on the development of myelomeningocele under the influence of environmental or genetic factors.

Heritable spina bifida in sheep: A potential model for fetal repair of myelomeningocele.

BACKGROUND/PURPOSE: In 2004, a heritable occurrence of spina bifida was reported in sheep on a farm in the United States. We maintained and characterized the spina bifida phenotype in this flock to assess its potential as an alternative surgical model. METHODS: A breeding strategy was developed in which the sheep were crossed to maintain or increase the occurrence of spina bifida. Measurements and observations were recorded regarding lesion size, birthweight, ambulatory capacity, or urological function, and necropsies were performed on spina bifida afflicted lambs in conjunction with magnetic resonance imaging to determine the character of the spina bifida defects and assess the presence of Chiari-like malformations or hydrocephalus. RESULTS: The defects were observed to be more prevalent in ram lambs, and the rate of spina bifida per litter could be increased through backcrossing or by selection of a productive ewe breed. The lambs displayed a range of ambulatory and urological deficits which could be used to evaluate new fetal repair methodologies. Finally, affected lambs were shown to demonstrate severe Chiari malformations and hydrocephalus. CONCLUSIONS: We have determined that use of these sheep as a natural source for spina bifida fetuses is feasible and could supplement the deficits of current sheep models for myelomeningocele repair. LEVEL OF EVIDENCE: Level IV.

Concepts in the neurosurgical care of patients with spinal neural tube defects: An embryologic approach.

BACKGROUND: The neural tube defects (NTDs) are a heterogeneous group of structural birth defects that arise from a complex array of multiple genetic and environmental factors and adversely affect the structure and function of the brain and spinal cord. Spinal NTDs are clinically more common than cranial NTDs. There remains a significant gap in linking the multiple NTD phenotypes to current genomic understanding. METHODS: This article summarizes the neurosurgical clinical approach to spinal NTDs by correlating each step of embryonic development of the human nervous system with key management concepts for defects that arise at that step. RESULTS: The NTDs are broadly classified as open or closed. Open defects include myelomeningocele (MMC), encephalocele, and anencephaly. Closed defects are also known as occult spinal dysraphism and are characterized by intact skin over the spinal defect. They are more common and often cause neurologic decline from tethered cord syndrome. Failure of primary neurulation gives rise to open myelomeningocele (MMC). Surgical closure of an open MMC focuses on realigning the tissue layers that failed to separate during neurulation. In utero closure is a promising recent technique. Chronic neurosurgical management largely focuses treating hydrocephalus. The Chiari II malformation is uniformly present in MMC patients and may cause brainstem dysfunction. Tethered spinal cord may progressively impair normal neurologic function but typically responds well to surgical untethering. CONCLUSIONS: Surgical closure of MMC centers on approximated realignment of embryologically disordered neural tissue. Clinical surgical management decisions in the spinal NTDs remains challenging but standardized principles have emerged.

SOX3 duplication: A genetic cause to investigate in fetuses with neural tube defects.

OBJECTIVE: Neural tube defects (NTDs) are one of the most common congenital anomalies caused by a complex interaction of many genetic and environmental factors. In about 10% of cases, NTDs are associated with genetic syndromes or chromosomal anomalies. Among these, SOX3 duplication has been reported in some isolated cases. The phenotype associated with this microduplication is variable and includes myelomeningocele (MMC) in both sexes as well as hypopituitarism and cognitive impairment in males. In order to determine the prevalence of this anomaly in fetuses with MMC, a retrospective cohort of fetuses with MMC was analyzed by quantitative PCR (qPCR) targeting SOX3 locus. METHODS: The detection of an SOX3 microduplication by chromosomal microarray analysis (CMA) in two female fetuses with MMC prompted us to analyze retrospectively by qPCR this gene in a cohort of 53 fetuses with MMC. RESULTS: In addition to our two initial cases, one fetus harboring an Xq27.1q28 duplication that encompasses the SOX3 gene was detected. CONCLUSION: Our data demonstrate that SOX3 duplication is a genomic imbalance involved in the pathogenesis of NTDs. In addition, our survey highlights the importance of CMA testing in fetuses with NTDs to enable genetic counseling upstream of any considerations of in utero fetal surgery.

Fetal myelomeningocele surgery: Only treating the tip of the iceberg.

OBJECTIVE: Fetal myelomeningocele (fMMC) surgery improves infant outcomes when compared with postnatal surgery. Surgical selection criteria and the option of pregnancy termination, however, limit the number of cases that are eligible for prenatal surgery. We aimed to quantify what proportion of cases could ultimately benefit from fetal therapy. METHODS: We retrospectively reviewed all cases of fMMC referred to a large tertiary care center over a 10-year period and assessed their eligibility for fetal surgery, pregnancy termination rates, and actual uptake of the surgery. RESULTS: Of 158 cases, 67 (42%) were ineligible for fetal surgery based on surgical exclusion criteria. Eleven fetuses (7%) had chromosomal anomalies, 10 of which (91%) had other anomalies on ultrasound. Thirty-four patients had a combination of maternal and fetal contraindications. Of the remaining 91 eligible cases (58%), 45 (49%) pregnancies were terminated, leaving only 46 (29% of initial 158 cases) as potential candidates for fetal repair. Actual uptake of fetal surgery was 15% (n = 14 of 91), but this increased after a national program was started. CONCLUSION: Only a minority of fMMC cases will ultimately undergo fetal surgery. These numbers support the centralization of care in expert centers.

Transgenerational Inheritance of Familial Lipomyelomeningocele.

Lipomyelomeningocele is a type of neural tube defect characterized by lipomatous tissue causing a defect in the vertebrae, infiltrating the dura, and tethering the spinal cord. Despite significant neurologic consequences, the underlying etiology remains poorly understood. We present a father and son with remarkably similar presentations of lipomyelomeningocele. Genetic testing did not reveal an underlying cause but whole exome sequencing identified variants in the ARHGAP29 and RADIL genes in the proband and his affected father. Genetic analyses of asymptomatic family members revealed several carriers of the ARHGAP29 or RADIL variants, but only the proband and his father carried both variants, suggesting a possible shared genetic mechanism. Rare cases of siblings affected with lipomyelomeningocele have suggested the possibility of autosomal recessive or germline mosaicism. We present the first documented cases of transgenerational lipomyelomeningocele with important implications for family counseling about the recurrence of lipomyelomeningocele.

Mutations in folate transporter genes and risk for human myelomeningocele.

The molecular mechanisms linking folate deficiency and neural tube defect (NTD) risk in offspring remain unclear. Folate transporters (SLC19A1, SLC46A1, SLC25A32, and FOLH1) and folate receptors (FOLR1, FOLR2, and FOLR3) are suggested to play essential roles in transporting folate from maternal intestinal lumen to the developing embryo. Loss of function variants in these genes may affect folate availability and contribute to NTD risk. This study examines whether variants within the folate transporter and receptor genes are associated with an increased risk for myelomeningocele (MM). Exons and their flanking intron sequences of 348 MM subjects were sequenced using the Sanger sequencing method and/or next generation sequencing to identify variants. Frequencies of alleles of single nucleotide polymorphisms (SNPs) in MM subjects were compared to those from ethnically matched reference populations to evaluate alleles' associated risk for MM. We identified eight novel variants in SLC19A1 and twelve novel variants in FOLR1, FOLR2, and FOLR3. Pathogenic variants include c.1265delG in SLC19A1 resulting in an early stop codon, four large insertion deletion variants in FOLR3, and a stop_gain variant in FOLR3. No new variants were identified in SLC46A1, SLC25A32, or FOLH1. In SLC19A1, c.80A>G (rs1051266) was not associated with our MM cohort; we did observe a variant allele G frequency of 61.7%, higher than previously reported in other NTD populations. In conclusion, we discovered novel loss of function variants in genes involved in folate transport in MM subjects. Our results support the growing evidence of associations between genes involved in folate transport and susceptibility to NTDs.

Amniotic fluid transcriptomics reflects novel disease mechanisms in fetuses with myelomeningocele.

BACKGROUND: Cell-free RNA in amniotic fluid supernatant reflects developmental changes in gene expression in the living fetus, which includes genes that are specific to the central nervous system. Although it has been previously shown that central nervous system-specific transcripts are present in amniotic fluid supernatant, it is not known whether changes in the amniotic fluid supernatant transcriptome reflect the specific pathophysiologic condition of fetal central nervous system disorders. In myelomeningocele, there is open communication between the central nervous system and amniotic fluid. OBJECTIVES: The purpose of this study was to identify molecular pathophysiologic changes and novel disease mechanisms that are specific to myelomeningocele by the analysis of amniotic fluid supernatant cell-free RNA in fetuses with open myelomeningocele. STUDY DESIGN: Amniotic fluid supernatant was collected from 10 pregnant women at the time of the open myelomeningocele repair in the second trimester (24.5±1.0 weeks); 10 archived amniotic fluid supernatant from sex and gestational age-matched euploid fetuses without myelomeningocele were used as controls (20.9±0.9 weeks). Differentially regulated gene expression patterns were analyzed with the use of human genome expression arrays. RESULTS: Fetuses with myelomeningocele had 284 differentially regulated genes (176 up- and 108 down-regulated) in amniotic fluid supernatant. Known genes that were associated with myelomeningocele (PRICKLE2, GLI3, RAB23, HES1, FOLR1) and novel dysregulated genes were identified in association with neurodevelopment and neuronal regeneration (up-regulated, GAP43 and ZEB1) or axonal growth and guidance (down-regulated, ACAP1). Pathway analysis demonstrated a significant contribution of inflammation to disease and a broad influence of Wnt signaling pathways (Wnt1, Wnt5A, ITPR1). CONCLUSION: Transcriptomic analyses of living fetuses with myelomeningocele with the use of amniotic fluid supernatant cell-free RNA demonstrated differential regulation of specific genes and molecular pathways relevant to this central nervous system disorder, which resulted in a new understanding of pathophysiologic changes. The data also suggested the importance of pathways that involve secondary disease, such as inflammation, in myelomeningocele. These newly identified pathways may lead to hypotheses that can test novel therapeutic targets as adjuncts to fetal surgical repair.