Malposed Semilunar Valves in Double Outlet Right Ventricle - A Pilot Genetic Analysis

在发育过程中，心脏流出道(OFT)主要起源于所谓的 第二心区(SHF)和OFT缺陷出现在所有先天性心脏病中的近30%。传统上， 成熟度通常被模拟为三个截然不同的事件--分离、对齐和旋转。双出口 右室(DORV)是当OFT未能适当调整自身以使全身和肺 流出可以从各自的脑室流出。虽然已经提出了几种动物模型来研究 DORV的分子基础，这些模型未能充分解释同时比对和 OFT的旋转，因此不能忠实地复制在临床环境中看到的DORV频谱。 临床上，DORV表现为一系列异常，并伴有大血管方向的相关缺陷- 从具有正常血缘关系的四联型DORV(NRGA)到转位型DORV 大动脉错位(MGA)。手术治疗和结果在这两个方面有很大的不同。 两种类型，因此，研究潜在的独特的分子缺陷具有内在的科学价值。这个 随附的提案寻求利用在DORV儿童中发现的基因突变来通知突变 出现在DORV的一种新的小鼠模型中。PI可以获得PCGC的临床和全部外显子组数据 DORV患者，这将被分析，以确定与DORV/NRGA和。 MGA。PI的实验室已经建立了一种独特的DORV小鼠模型，其中ISL-CRE驱动的DLL4f/wt小鼠 表现出DORV/NRGA，而FGF8的部分敲除增加导致DORV/MGA。这个系统 提供了利用多基因遗传模式来模拟临床相关的DORV表型的机会 变种。这两组病变的RNA-seq分析将用于鉴定小鼠的突变。叠加 人类和老鼠的数据将为理解后续分析的相关途径铺平道路。 鉴于PI是一名执业的先天性心脏病外科医生和心脏发育生物学研究人员， 这一提议的关键优点是利用人类数据在一种新的老鼠模型中进行分析。 这种概念性的方法是由PI在护理患有DORV的儿童方面的临床专业知识推动的，它有 还提供了研究按临床表型分层的基因突变的能力。的实验室方面 该项目自然建立在PI研究OFT中DLL4信令的成熟专业知识的基础上 开发，并利用作为NHLBI K08赠款的一部分建立的DORV模型。此外，该提案 得到了南加州大学翻译基因组研究所的支持，该研究所拥有一个强大的平台来进行 这项研究提出了一种遗传分析方法。本着R03机制的精神，这项试点工作旨在 分析来自预先存在的临床外显子组序列和已建立的小鼠胚胎的遗传数据。 这项工作的成功完成将为更有力和临床相关的评估提供平台 灵活的对齐和旋转铺设方式，适用于较大的R01应用。

During development, the cardiac outflow tract (OFT) arises primarily from progenitor cells in the so-called second heart field (SHF) and OFT defects are seen in nearly 30% of all congenital heart disease. Traditionally, OFT maturation has been modeled as three distinct events – septation, alignment and rotation. Double outlet right ventricle (DORV) results when the OFT fails to appropriately align itself such that systemic and pulmonary outflows can exit from the respective ventricles. Although several animal models have been proposed to study the molecular basis for DORV, these models have failed to sufficiently explain simultaneous alignment and rotation of the OFT, and as such do not faithfully phenocopy the spectrum of DORV seen in the clinical setting. Clinically, DORV presents as a spectrum of abnormalities with associated defects in great vessel orientation - ranging from the tetralogy-type DORV with normally related great arteries (NRGA) to transposition-type DORV with malposed great arteries (MGA). Surgical management and outcomes are vastly different between these two types and, hence, studying the underlying unique molecular defects is of intrinsic scientific merit. The accompanying proposal seeks to utilize genetic mutations identified in children with DORV to inform mutations seen in a novel mouse model of DORV. The PI has access to clinical and whole exome data from the PCGC of patients with DORV, which will be analyzed to identify genotype-phenotype correlation with DORV/NRGA vs. MGA. The PI's lab has established a unique mouse model of DORV, wherein Isl-Cre driven DLL4f/wt mice exhibit DORV/NRGA, whereas the addition of partial knockout of FGF8 results in DORV/MGA. This system provides the opportunity to utilize a polygenic inheritance pattern to model clinically relevant DORV phenotypic variants. RNA-seq analysis from these two lesion sets will be used to identify murine mutations. Superimposing human and murine data will pave way for the understanding of relevant pathways for subsequent analyses. Given that the PI is a practicing congenital heart surgeon and a cardiac developmental biology researcher, a key strength of this proposal is the utilization of human data to inform the analysis in a novel mouse model. The conceptual approach is driven by the PI’s clinical expertise in caring for children with DORV, which has also provided the ability to study genetic mutations stratified by clinical phenotype. The laboratory aspect of this project naturally builds upon on the PI’s established expertise studying DLL4 signaling in OFT development, and utilizes a model of DORV set up as part of a K08 grant from NHLBI. In addition, the proposal enjoys the support of USC’s Institute of Translational Genomics, which has a robust platform to undertake the kind of genetic analysis proposed in this study. In the spirit of the R03 mechanism, this pilot work seeks to analyze genetic data from pre-existing clinical exome sequences and from established mouse embryos. Successful completion of this work will provide a platform for more robust and clinically relevant evaluation of OFT alignment and rotation paving way for a larger R01 application.