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

在发育过程中，心脏流出道（OFT）主要来自所谓的前体细胞。 第二心野（SHF）和OFT缺陷见于所有先天性心脏病的近30%。传统上， OFT成熟被建模为三个不同的事件-分隔，对齐和旋转。双出口 右心室（DORV）的结果时，OFT未能适当地对齐本身， 流出物可以从各自的心室排出。尽管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对齐， 因此，OFT的旋转不能忠实地复制临床环境中所见的DORV谱。 在临床上，DORV表现为一系列异常，伴有大血管方向的相关缺陷- 从具有正常相关大动脉（NRGA）的四联型DORV到转位型DORV 大动脉错位（MGA）手术管理和结果在这些之间有很大的不同 因此，研究潜在的独特分子缺陷具有内在的科学价值。的 伴随的提案寻求利用在DORV儿童中鉴定的基因突变来告知突变 在DORV的新型小鼠模型中观察到。PI可以访问来自PCGC的临床和全外显子组数据， DORV患者，将对其进行分析，以确定DORV/NRGA与 MGA。PI的实验室已经建立了独特的DORV小鼠模型，其中Isl-Cre驱动的DLL 4f/wt小鼠 表现出DORV/NRGA，而加入部分敲除FGF 8导致DORV/MGA。该系统 提供了利用多基因遗传模式来模拟临床相关DORV表型的机会 变体。来自这两个病变组的RNA-seq分析将用于鉴定鼠突变。叠加 人类和鼠的数据将为理解相关途径铺平道路，以便进行后续分析。 鉴于PI是一名执业先天性心脏病外科医生和心脏发育生物学研究人员， 该提案的关键优势是利用人类数据为新型小鼠模型的分析提供信息。 概念方法是由PI在照顾DORV儿童方面的临床专业知识驱动的， 还提供了研究按临床表型分层的遗传突变的能力。实验室方面， 这个项目自然建立在PI研究OFT中DLL 4信令的专业知识基础上 开发，并利用DORV的模型建立从NHLBI的K 08赠款的一部分。此外，提案 享有南加州大学翻译基因组学研究所的支持，该研究所拥有一个强大的平台，可以承担 本研究中提出的遗传分析。本着R 03机制的精神，这项试点工作力求 分析来自预先存在的临床外显子组序列和来自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可靠和临床相关的评估提供一个平台， OFT对准和旋转为更大的R 01应用铺平了道路。

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.