Genetic and Functional Dissection of Congenital Anomalies of the Brain

项目总结 人脑发育仍然是一个不完全了解的过程，但这是先天的异常。 复杂的结构每年影响大约3/1,000名孕妇和2000多名新生儿 这对美国的医疗保健系统造成了沉重的负担。先天大脑异常， 以广泛的表型异质性为特点，包括但不限于无前脑畸形， 脑裂、无脑、脑膨出、小头畸形、脑室增大、小脑发育不良 皮质发育障碍，如无脑畸形。配对方法：(1)产前诊断使用 超声和胎儿MRI相结合来表征异常表型；(2)遗传分析 确定原因损害，极大地提高了准确咨询家属诊断的能力， 预后和复发风险。近年来，产前全外显子组测序(WES)已应用于 致死性或多发性胎儿异常的病例作出分子诊断，否则无法 与传统测试相一致。我们小组和其他使用WES的飞行员数据显示，诊断率为16%- 在多发性胎儿畸形中占30%，而在单纯性脑异常中仅为1%-2%，表明危重 需要提高诊断能力，识别对人脑发育至关重要的新基因。我们假设 未解决的胎儿病例过多在很大程度上是由于：(1)我们的 了解与产前发病有关的脑部异常的基因型谱；以及(2) 群体遗传学在确定新候选基因中罕见变异因果关系方面的局限性。给你，两个 CTSA资助的团队处于产前遗传诊断和斑马鱼体内模型研究的前沿 北卡罗来纳大学和杜克大学的人类疾病中心将联合起来，克服目前诊断方面的挑战 脑部异常与产前发病有关。我们将把外显子组和基因组范围的变异数据与 实验上易驯化的相关模型系统，斑马鱼(Danio Rerio)。我们假设 使用产前WES数据的生物信息学过滤器将揭示新的候选基因，这些基因可以应用于 斑马鱼模型产生对人脑发育至关重要的初步发现并转化为改进 临床护理。首先，我们将对10例临床确诊的中枢神经系统胎儿进行生物信息学分析。 使用分层过滤策略的异常及其父级；我们将迭代地应用此分析范例 给32名预期登记的胎儿及其家人。第二，我们将确定候选基因的相关性 使用最先进的基因组编辑和确定大脑发育和变异致病性 斑马鱼的表型工具。我们工作的完成将扩大我们对分子的理解 管理产前大脑发育的过程；容易建立临床-研究混合平台 适用于其他可通过胎儿成像检测到的解剖器官缺陷；并建立了一套 异常的中枢神经系统发育，具有未来用于治疗靶点识别的潜力。

PROJECT SUMMARY Human brain development remains an incompletely understood process, yet congenital abnormalities of this complex structure affect approximately 3/1,000 pregnancies and more than 2000 newborns annually in the United States, posing a substantial burden on the health care system. Congenital brain abnormalities, hallmarked by vast phenotypic heterogeneity, include but are not limited to holoprosencephaly, schizencephaly, anencephaly, encephalocele, microcephaly, ventriculomegaly, cerebellar hypoplasia, and disorders of cortical development, such as lissencephaly. The paired approach of: (1) prenatal diagnosis using a combination of ultrasound and fetal MRI to characterize aberrant phenotypes; with (2) genetic analysis to determine causal lesions, has greatly improved the ability to accurately counsel families about diagnosis, prognosis, and recurrence risk. More recently, prenatal whole exome sequencing (WES) has been applied in cases of lethal or multiple fetal abnormalities to make a molecular diagnosis that otherwise could not be identified with traditional testing. Pilot data from our group and others using WES show a diagnostic rate of 16- 30% in cases of multiple fetal abnormalities, but only 1-2% in isolated brain abnormalities, indicating a critical need to improve diagnostic capabilities and identify novel genes critical to human brain development. We posit that the overabundance of unresolved fetal cases is in large part due to: (1) a knowledge gap in our understanding of the repertoire of genotypes underlying brain abnormalities with prenatal onset; and (2) limitations of population genetics to establish causality of rare variants in novel candidate genes. Here, two CTSA-funded teams who are at the forefronts of prenatal genetic diagnostics and in vivo zebrafish modeling of human disease, at UNC and Duke, respectively, will team up to overcome the current challenges of diagnosing brain abnormalities with a prenatal onset. We will intersect exome- and genome-wide variation data with experimentally tractable and relevant model systems, zebrafish (Danio rerio). We hypothesize that bioinformatics filters using prenatal WES data will reveal novel candidate genes, which can be applied to a zebrafish model to generate initial discoveries critical to human brain development and translate into improved clinical care. First, we will perform bioinformatic analysis of 10 clinically ascertained fetuses with CNS anomalies and their parents using a tiered filtering strategy; and we will apply this analysis paradigm iteratively to 32 prospectively enrolled fetuses and their families. Second, we will establish relevance of candidate genes to brain development and determine variant pathogenicity using state-of-the-art genome editing and phenotyping tools in zebrafish. Completion of our work will expand our understanding of the molecular processes governing prenatal brain development; establish a clinical-research hybrid platform readily applicable to other anatomical organ defects detectable by fetal imaging; and build a suite of animal models of aberrant CNS development with potential for future use in therapeutic target identification.