Quantitative trait and transcriptome analysis of genetic complexity underpinning cardiac interatrial septation in mice using an advanced intercross line
Curation statements for this article:-
Curated by eLife
eLife assessment
This important study of mouse genetic variation in atrial septum formation, a trait correlated with the patent foramen ovale (PFO) cardiac defect, provides convincing evidence for 37 quantitative trait loci (QTL) affecting this trait, combining genetic mapping with transcriptome analysis to zero in on relevant pathways and candidate genes within the QTL, and validating the role of one gene in tissue culture. The paper provides an important resource for hypothesis generation and future studies, which could lead to novel diagnostic or therapeutic approaches that target atrial septal defects in common congenital heart disease.
This article has been Reviewed by the following groups
Listed in
- Evaluated articles (eLife)
- Genetics and Genomics (eLife)
Abstract
Unlike single-gene mutations leading to Mendelian conditions, common human diseases are likely to be emergent phenomena arising from multilayer, multiscale, and highly interconnected interactions. Atrial and ventricular septal defects are the most common forms of cardiac congenital anomalies in humans. Atrial septal defects (ASD) show an open communication between the left and right atria postnatally, potentially resulting in serious hemodynamic consequences if untreated. A milder form of atrial septal defect, patent foramen ovale (PFO), exists in about one-quarter of the human population, strongly associated with ischaemic stroke and migraine. The anatomic liabilities and genetic and molecular basis of atrial septal defects remain unclear. Here, we advance our previous analysis of atrial septal variation through quantitative trait locus (QTL) mapping of an advanced intercross line (AIL) established between the inbred QSi5 and 129T2/SvEms mouse strains, that show extremes of septal phenotypes. Analysis resolved 37 unique septal QTL with high overlap between QTL for distinct septal traits and PFO as a binary trait. Whole genome sequencing of parental strains and filtering identified predicted functional variants, including in known human congenital heart disease genes. Transcriptome analysis of developing septa revealed downregulation of networks involving ribosome, nucleosome, mitochondrial, and extracellular matrix biosynthesis in the 129T2/SvEms strain, potentially reflecting an essential role for growth and cellular maturation in septal development. Analysis of variant architecture across different gene features, including enhancers and promoters, provided evidence for the involvement of non-coding as well as protein-coding variants. Our study provides the first high-resolution picture of genetic complexity and network liability underlying common congenital heart disease, with relevance to human ASD and PFO.
Article activity feed
-
-
eLife assessment
This important study of mouse genetic variation in atrial septum formation, a trait correlated with the patent foramen ovale (PFO) cardiac defect, provides convincing evidence for 37 quantitative trait loci (QTL) affecting this trait, combining genetic mapping with transcriptome analysis to zero in on relevant pathways and candidate genes within the QTL, and validating the role of one gene in tissue culture. The paper provides an important resource for hypothesis generation and future studies, which could lead to novel diagnostic or therapeutic approaches that target atrial septal defects in common congenital heart disease.
-
Reviewer #1 (Public Review):
Marjaneh et al. studied the atrial septal variation through QTL mapping of inbred mouse strains which show extremes of septal phenotypes. The analysis discovered many interesting septal QTLs. Furthermore, the authors identified high-confidence candidate deleterious variants through whole genome sequencing of parental strains and analyzed variant architecture across gene features.
Overall, this is a comprehensive study that will provide a useful reference for the field. It will be a useful tool for hypothesis generation, which could lead to research on therapies that target atrial septal or common congenital heart disease.
-
Reviewer #2 (Public Review):
This manuscript by Marjaneh et al is an original research article that aimed to understand the genetic complexity of atrial septal defects by using QTL analysis in advanced intercross lines (AIL) QSi5 and 129T2/SvEms mouse strains, which represent mice with extremes of atrial septal phenotypes. This study is built on previous work by the authors (Biben. 2000), in which they developed three quantitative parameters of atrial septal morphology. These quantitative traits were previously proven by the authors to be associated with the prevalence of PFO across a variety of genetic backgrounds. Using an F2 design of the same strains they have previously identified 13 significant or suggestive QTL affecting these quantitative traits, (Kirk. 2006).
The current manuscript extends the previous analysis using the AIL …
Reviewer #2 (Public Review):
This manuscript by Marjaneh et al is an original research article that aimed to understand the genetic complexity of atrial septal defects by using QTL analysis in advanced intercross lines (AIL) QSi5 and 129T2/SvEms mouse strains, which represent mice with extremes of atrial septal phenotypes. This study is built on previous work by the authors (Biben. 2000), in which they developed three quantitative parameters of atrial septal morphology. These quantitative traits were previously proven by the authors to be associated with the prevalence of PFO across a variety of genetic backgrounds. Using an F2 design of the same strains they have previously identified 13 significant or suggestive QTL affecting these quantitative traits, (Kirk. 2006).
The current manuscript extends the previous analysis using the AIL approach at F14. This design, the fine mapping approach, and the rigorous downstream analysis allowed them to refine their previous findings. In addition, several new QTLs were discovered. Remarkably, the resolution was increased and the overlap between QTL for different traits was enhanced. Furthermore, they performed whole genome sequencing of the parental strains and identified high-confidence deleterious variants that are enriched in known human CHD genes as well as the genes within QTL regions that are expressed in the atrial septum, such as SMAD6. They also performed transcriptome analysis of septa at different developmental stages in parental strains and identified networks enriched in the ribosome, nucleosome, mitochondrial, and ECM biosynthesis underlying septal variation.
Overall, the manuscript was built on a clear rationale and employed a suitable genomics approach to address the topic. The results provide a substantial and important extension of the previous work at a larger scale and a higher level of resolution. The findings improve the status of current knowledge and provide valuable resources to unravel the genetic complexity of CHDs, with relevance to human PFO. The significance is deemed to be "Important" given the large-scale approach, the specificity of quantitative measures, and the resolution of the analysis pipeline. Analysis steps are well-designed providing potential candidate targets from their network analysis. Pending functional validation and confirmatory evidence of the causality in future mechanistic studies, the outcomes may lead to novel diagnostic and translational values.
-
Reviewer #3 (Public Review):
In previous studies, Harvey and colleagues described several genetically-influenced biometric parameters correlated with the patent foramen ovale (PFO) cardiac defect (Biben et al., 2000) and identified 13 quantitative trait loci (QTL) that affect these traits using a murine F2 intercross design with mouse strains demonstrating extreme septal phenotypes (Kirk et al., 2006). In the submitted manuscript, Marjaneh et al. follow up and refine these studies with a more in-depth QTL analysis utilizing an advanced intercross design (F14), combined with genome and transcriptome sequencing data supporting a role for the identified QTL in atrial septation. The paper is mostly genetic analysis with follow-up informatics and one example of a validated variant. The results are important, and implicate dozens of loci and …
Reviewer #3 (Public Review):
In previous studies, Harvey and colleagues described several genetically-influenced biometric parameters correlated with the patent foramen ovale (PFO) cardiac defect (Biben et al., 2000) and identified 13 quantitative trait loci (QTL) that affect these traits using a murine F2 intercross design with mouse strains demonstrating extreme septal phenotypes (Kirk et al., 2006). In the submitted manuscript, Marjaneh et al. follow up and refine these studies with a more in-depth QTL analysis utilizing an advanced intercross design (F14), combined with genome and transcriptome sequencing data supporting a role for the identified QTL in atrial septation. The paper is mostly genetic analysis with follow-up informatics and one example of a validated variant. The results are important, and implicate dozens of loci and hundreds of genes (including those in the BMP pathway, and others known to be essential for cardiac morphogenesis) in atrial septum formation, highlighting the complexity of the processes involved. This paper will be an important resource for the field and sets the stage for a follow-up to validate the many candidates identified that may impact cardiac morphogenesis and atrial septation, specifically. The manuscript is well-written and straightforward and does not suffer from major errors in logic or interpretation. The identification of implicated genetic variants will benefit the field of cardiac development and may inform the advancement of future therapeutics for human patients with PFO (for identified coding variants, in particular).
-
