Genomics and functional dissection of fetal brain abnormalities using a prenatal cohort

摘要 胎儿脑异常(FBA)是最常见的产前超声检查异常之一。 占出生缺陷的约20%，给医疗保健系统带来了巨大的负担。可以隔离FBA 或综合征型，并具有巨大的表型异质性。应用配对方法进行产前诊断 超声表征异常表型和基因分析以确定原因损害已有改进 就诊断、预后和复发风险向家庭提供准确咨询的能力。最近，产前 外显子组测序(ES)已被应用于致死性或多发性胎儿畸形的病例中，以确定 分子诊断，否则无法与传统的检测确定。我们的团队和其他使用ES的人 对多发性胎儿畸形的诊断率为23.6%，而对单纯性胎儿畸形的诊断率仅为2.6% 异常，表明需要提高对FBA的诊断能力。我们假设过多的 未解决的胎儿病例是由于我们对产前潜在的基因型谱的理解存在差距。 FBA和群体遗传学的局限性，以确定新候选基因中罕见变异的因果关系。我们的 在人类疾病的产前遗传诊断和活体斑马鱼建模方面处于领先地位的团队将 克服目前诊断产前FBA的挑战。我们将在外显子组和基因组范围内 与相关模式系统(斑马鱼)的变异。 我们假设我们将1)产生初步发现 通过对斑马鱼中新的候选FBA基因进行建模，与人类大脑发育直接相关；以及2) 利用全基因组测序(WGS)和深度表型分析改进FBA的产前诊断。我们将：1. 对200多例临床确诊的胎儿及其父母进行生物信息学分析 对已有的亲子三外显组数据的筛选策略2.对114名预期登记的人进行WGS 胎儿及其父母与全面的产前和出生后表型数据配对，以进一步 确定FBA的基因型/表型；3.确定与FBA发生和发展相关的候选基因 使用基因组编辑和表型分析工具确定斑马鱼的变异致病性。我们的工作将会扩大 了解控制人脑发育的分子过程，建立临床研究 易于应用于FBA和其他可通过胎儿成像检测的解剖缺陷的混合平台，构建 FBA发育异常的动物模型，具有未来用于治疗靶点识别的潜力。我们的 立竿见影的结果将改善产前诊断的FBA的咨询/管理，并导致未来的工作 为FBA制定新的治疗和预防策略。

ABSTRACT Fetal brain abnormalities (FBA) are one of the most common prenatal sonographic abnormality detected and account for ~20% of birth defects posing a substantial burden on the health care system. FBA can be isolated or syndromic and have vast phenotypic heterogeneity. The paired approach of prenatal diagnosis using ultrasound to characterize aberrant phenotypes with genetic analysis to determine causal lesions has improved the ability to accurately counsel families about diagnosis, prognosis, and recurrence risk. Recently, prenatal exome sequencing (ES) has been applied in cases of lethal or multiple fetal abnormalities to determine a molecular diagnosis that otherwise could not be identified with traditional testing. Our group and others using ES have shown a diagnostic rate of 23.6% in cases of multiple fetal abnormalities, but only 2.6% in isolated FBA abnormalities, indicating a need to improve diagnostic capabilities for FBA. We posit that the overabundance of unresolved fetal cases is due to a gap in our understanding of the repertoire of genotypes underlying prenatal FBA and limitations of population genetics to establish causality of rare variants in novel candidate genes. Our team who is at the forefront of prenatal genetic diagnostics and in vivo zebrafish modeling of human disease will overcome the current challenges of diagnosing prenatal FBA. We will intersect exome- and genome-wide variation with a relevant model system (zebrafish). We hypothesize that we will 1) generate initial discoveries directly relevant to human brain development by modeling novel candidate FBA genes in zebrafish; and 2) improve prenatal diagnosis for FBA using whole genome sequencing (WGS) and deep phenotyping. We will: 1. Perform bioinformatic analysis of 200+ clinically ascertained fetuses with FBA and their parents using a tiered filtering strategy on already available parent-fetus trio exome data 2. Perform WGS on 114 prospectively enrolled fetuses and their parents paired with comprehensive prenatal and postnatal phenotypic data to further characterize genotype/phenotype of FBA; 3. Establish relevance of candidate genes to FBA development and determine variant pathogenicity using genome-editing and phenotyping tools in zebrafish. Our work will expand the understanding of molecular processes governing human brain development, establish a clinical-research hybrid platform readily applicable to FBA and other anatomical defects detectable by fetal imaging, build an animal model of aberrant FBA development with potential for future use in therapeutic target identification. Our immediate results will improve counseling/management of prenatally diagnosed FBA and lead to future work to develop novel therapeutic and preventative strategies for FBA.