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.

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.

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.

CITED2 Mutations in Conserved Regions Contribute to Conotruncal Heart Defects in Chinese Children.

Conotruncal heart defects (CTDs) are severe malformations of outflow tract with heterogeneous morphology. Several missense variants of CITED2 have been identified to cause CTDs in recent researches. In this study, we screened the coding regions of CITED2 in 605 Chinese children with CTDs and found two possible pathogenic mutant sites: p.Q117L and p.T257A, both located in the conserved regions of CITED2. Then, we investigated the biological and functional alterations of them. Western blotting showed low level of protein expression of mutant Q117 and T257A compared with wild-type CITED2. Dual-luciferase reporter assay demonstrated that mutant Q117 and T257A decreased the ability of CITED2 to modulate the expression of paired-like homeodomain transcription factor 2 gamma (PITX2C), which are closely related to cardiac growth and left-right patterning. Meanwhile, T257A also exhibited impaired ability to mediate vascular endothelial growth factor expression, another gene closely associated with the normal development of cardiovascular system. Three-dimensional molecular conformation showed reduced hydrogen bond between Asp254 and mutant Thr257, indicating the weakened stability and binding ability of CITED2. All these results suggest that CITED2 mutations in conserved regions lead to disease-causing biological and functional changes and may contribute to the occurrence of CTDs.

Neural tube defects and atypical deletion on 22q11.2.

The 22q11.2 deletion syndrome (22q11.2DS) is a common microdeletion disorder. Most of the patients show the common 3 Mb deletion but proximal 1.5 Mb deletion and unusual deletions located outside the common deleted region, have been detected particularly with the advance of comparative cytogenomic microarray technologies. The individuals reported in the literature with unusual deletions involving the 22q11 region, showed milder facial phenotypes, decreased incidence of cardiac anomalies, and intellectual disability. We describe two sibs with an atypical 0.8 Mb microdeletion of chromosome 22q11 who both showed myelomeningocele and mild facial dysmorphisms. The association between neural tube defect and the clinical diagnosis of Di George anomaly/velocardiofacial syndrome is well documented in the literature, but not all cases had molecular studies to determine breakpoint regions. This report helps to narrow a potential critical region for neural tube defects associated with 22q11 deletions.

Estudio de asociación de base familiar entre polimorfismos de MTHFR y mielomeningocele en Chile / Methylenetetrahydrofolate reductase polymorphisms as risk factors for myelomeningocele

Background: Mandatory fortification with folic acid (FA) was implemented in Chile in 2000. Thereafter, the rate of spina bifida decreased by 52 to 55%. Genetic abnormalities in folate metabolism may be involved in the etiology of spina bifida. Aim: To evaluate the association between myelomeningocele (MM) and c.A1298C and c.C677T polymorphisms within the coding gene for 5,10-methylenetetrahydrofolate reductase (MTHFR) in the Chilean population. Material and Methods: These polymorphisms were genotyped in 105 patients showing isolated MM, born after the onset of FA fortification, and in their parents. The transmission disequilibrium test (TDT) was performed to evaluate alterations in the transmission of both alleles and haplotypes MTHFR polymorphism. We also evaluated the presence of parent-origin-effect (POE) of alleles using the Clayton’s extension of the TDT. Results: TDT analysis showed no significant distortions in the transmission of alleles or haplotypes. Moreover, although the POE showed increased risk for maternally derived allele, this risk was not statistically significant. Conclusions: The studied variants in the MTHFR gene (c.C677T and c.A1298C) do not constitute risk factors for MM in this sample of Chilean patients and their parents.

Neural tube defects--disorders of neurulation and related embryonic processes.

Neural tube defects (NTDs) are severe congenital malformations affecting 1 in every 1000 pregnancies. 'Open' NTDs result from failure of primary neurulation as seen in anencephaly, myelomeningocele (open spina bifida), and craniorachischisis. Degeneration of the persistently open neural tube in utero leads to loss of neurological function below the lesion level. 'Closed' NTDs are skin-covered disorders of spinal cord structure, ranging from asymptomatic spina bifida occulta to severe spinal cord tethering, and usually traceable to disruption of secondary neurulation. 'Herniation' NTDs are those in which meninges, with or without brain or spinal cord tissue, become exteriorized through a pathological opening in the skull or vertebral column (e.g., encephalocele and meningocele). NTDs have multifactorial etiology, with genes and environmental factors interacting to determine individual risk of malformation. While over 200 mutant genes cause open NTDs in mice, much less is known about the genetic causation of human NTDs. Recent evidence has implicated genes of the planar cell polarity signaling pathway in a proportion of cases. The embryonic development of NTDs is complex, with diverse cellular and molecular mechanisms operating at different levels of the body axis. Molecular regulatory events include the bone morphogenetic protein and Sonic hedgehog pathways which have been implicated in control of neural plate bending. Primary prevention of NTDs has been implemented clinically following the demonstration that folic acid (FA), when taken as a periconceptional supplement, can prevent many cases. Not all NTDs respond to FA, however, and adjunct therapies are required for prevention of this FA-resistant category.

Genetic studies of the cystathionine beta-synthase gene and myelomeningocele.

BACKGROUND: Among infants born with spina bifida, the most common defect is myelomeningocele (MM). The prevention of MM by maternal periconceptional folic acid (FA) supplementation has been studied extensively. The protective effect provided by FA suggests that the genes involved in folate metabolism, such as cystathionine beta-synthase (CBS), warrant further investigation. METHODS: This study sequenced the DNA from 96 patients with MM to identify novel potential disease-causing variants across the 17 exons of the CBS gene. The frequencies of known single nucleotide polymorphisms (SNPs) were identified, and sequences that differed from the reference sequences were considered novel variants. Statistical analysis was performed using two-sided Fisher's exact test to compare frequencies of SNPs between groups of patients and the known population frequencies. RESULTS: We found a new variant in exon 3 in one patient that results in a G/A change subsequently encoding a stop codon. In addition, we found a new variant in the 3'-UTR of exon 17. Allele frequencies for 10 known single nucleotide polymorphisms (SNPs) were determined: rs234706, rs72058776, rs1801181, rs6582281, rs71872941, rs12613, rs706208, rs706209, rs73906420, and rs9982921. Of the remaining 48 known SNPs, all tested DNAs were homozygous for the major allele. CONCLUSION: We identified a previously undescribed variant in exon 3 that encodes a stop codon, thus halting downstream translation of the CBS protein. According to the Human Splicing Finder, the 3'-UTR variant found in exon 17 is predicted to abolish the recognition sites for two splice binding factors, SRp40 and SF2/ASF. The functional significance of the 3'-UTR mutation needs to be investigated.

Prevalence of cystathionine beta synthase gene mutation 852Ins68 as a possible risk for neural tube defects in eastern India.

Cystathionine beta synthase gene (CßS) catalyzes the condensation of homocysteine with serine, forming cystathionine by the transsulfuration pathway. Disruption of CßS enzyme activity due to defective folic acid metabolism increases the risk factor for neural tube defects. We evaluated the CßS gene mutation in 25 children with neural tube defects (NTDs), including lumbosacral and thoracic myelomeningocele and open NTDs and mothers of cases, along with 25 healthy children and their mothers, serving as controls. Genomic DNA was isolated to assess the polymorphism of 852Ins68 in the CßS gene using PCR-RFLP analysis and nucleotide sequencing techniques. The 68-bp insertion was observed in one of the 25 NTD cases (lumbosacral myelomeningocele), and in two of the mothers of NTD cases. Statistical analysis was carried out using the Fischer exact probability test, which showed a lack of significance (P > 0.05), but the odds ratio of 2.08 with 95% confidence interval of 0.17-24.6 in NTDs mother was quite high because of the small sample size. However, the study was further extended to find out the involvement of specific nucleotide sequences, which again confirmed the 852Ins68 insertion and replacement of nucleotides (TCCAT to GGGG) in lumbosacral myelomeningocele (due to other category of NTDs), suggesting that it could be an independent risk factor for birth defects, including NTDs.

Association of retinoic acid receptor genes with meningomyelocele.

BACKGROUND: Neural tube defects (NTDs) occur in as many as 0.5-2 per 1000 live births in the United States. One of the most common and severe neural tube defects is meningomyelocele (MM) resulting from failed closure of the caudal end of the neural tube. MM has been induced by retinoic acid teratogenicity in rodent models. We hypothesized that genetic variants influencing retinoic acid (RA) induction via retinoic acid receptors (RARs) may be associated with risk for MM. METHODS: We analyzed 47 single nucleotide polymorphisms (SNPs) that span across the three retinoic acid receptor genes using the SNPlex genotyping platform. Our cohort consisted of 610 MM families. RESULTS: One variant in the RARA gene (rs12051734), three variants in the RARB gene (rs6799734, rs12630816, rs17016462), and a single variant in the RARG gene (rs3741434) were found to be statistically significant at p < 0.05. CONCLUSION: RAR genes were associated with risk for MM. For all associated SNPs, the rare allele conferred a protective effect for MM susceptibility.