Ultrasonography On Screening The Development Of Normal Fetal Cerebral Cortex And Exome Study Of Genes Related To Abnormal Intracranial Structure

Research Background: Malformations of cortical development(MCD)is a general term for a series of abnormal intracranial structures and it is a common cause of neurodevelopmental delay and epilepsy as well.In this study,examination of the development of the cerebral cortex was first included during the normal prenatal examination.Based on larger set of samples,the development of the fetal cerebral cortex at different gestational weeks was studied using ultrasound technology and the laws of its growth and development were summarized.Then,whole-exome sequencing(WES)technology was used to detect the cord blood or villi of 11 fetuses with abnormal intracranial structures,and bioinformatics analysis was used to identify candidate genes that may be related to the pathogenesis of abnormal intracranial structure,and the protein structure of these mutants was predicted.These findings provide new candidate genes of abnormal intracranial structure and new ideas for understanding the pathogenesis of abnormal intracranial structure.Our study was divided into two parts.Part 1: The clinical application of ultrasound in the screening of fetal cerebral gyrus and sulci.Objective: Use the ultrasound technology to investigate the growth and development of the brain sulcus by measuring the main sulcus of the fetus at different gestational weeks.Methods: Ultrasound examination of 2406 pregnant women of different gestational weeks,the depth and width of the sylvian fissures,the depth of the parieto-occipital fissures,the angle of the parieto-occipital fissures,and the depth of the calcarine fissures were measured to evaluate the development trend of these sulci.Results:(1)The depth and width of the fetal sylvian fissures,the depth of the parieto-occipital fissures and the depth of the calcarine fissures were positively correlated with the gestational age(P<0.05);(2)The relationship between the fetal parieto-occipital fissure angle and the gestational age was negatively correlated(P<0.05);(3)According to the morphology of the fetal brain sulcus,it can be divided into three levels according to its development order to judge the maturity of the sulci.Conclusion: The morphology of the fetal brain sulcus and the ultrasound measured value change with the increase of gestational age.With the morphological characteristics of the fetal brain sulcus at different gestational weeks,the development of the fetal brain sulcus can be evaluated.Therefore,ultrasound technology is of great help to the assessment of the development of the fetal cerebral cortex and can provide more imaging evidences for prenatal diagnosis and consultation.Part 2: Identification of genetic mutations in abnormal brain fetus with normal karyotypes using WESObjective: To identify new abnormal intracranial structure pathogenic mutations,we performed WES for the cord blood and villi tissues of 11 fetuses with abnormal intracranial structures.We identified potential pathogenic mutations related to abnormal intracranial structure,and predicted the protein structure changes caused by these mutations.Methods:(1)The umbilical blood or villus tissue samples of fetuses with abnormal intracranial structures were subjected to WES.(2)Using BWA software to align the high-throughput sequencing data to the human genome;(3)Using genome analysis toolkit(GATK),SAM tools and other software to detect and identify single base substitutions(SNS)and base insertions and deletions(insert and delect,indel)mutations;(4)Compare,annotate and analyze SNS and In Del mutations based on the annotated mutations in db SNP and 1000 Genomes Project database;(5)Using functional enrichment analysis on genes of which protein sequences were changed in 11 samples.Results:(1)A total of 1035 genes whose protein sequences were changed in 11 fetuses were identified.(2)The results of functional enrichment analysis on these 1035 genes showed that they are enriched biological processes such as cell migration and cell differentiation and in the several signal pathways such as microtubule formation,Rho and ATPbing,indicating that genes involved in these functions play an important role in the normal development of the brain.Mutations occurred in these genes may lead to abnormal intracranial structure.(3)Seven genes with protein sequence changed in at least three patients were identified,including CTBP2,CTDSP2,HLA-DRB5,LZTFL1,MUC19,MUC 4,and MUC6.Mutations in CTDSP2 and CTBP2 may have the greatest impact on the formation of abnormal intracranial structure.Conclusion: WES technology combined with bioinformatics analysis technology can be used for genetic detection of fetal cerebral cortical development abnormalities,which can obtain the whole exome information of embryos and discover gene mutations that cause abnormal cerebral cortical development.Our study provide new clues for understanding the molecular mechanism of abnormal intracranial structure.