ABSTRACT 512

Abstract

Background and aims: Congenital heart disease (CHD) is a significant cause of infant morbidity and mortality. Yet, most of the genetic burden remains unexplained. Currently, analysis of exomes and copy number variations are identifying numerous sequence variations in patients with CHDs. These genomics technologies have revolutionized our ability to detect genetic changes in our patients. Aims: However, determining disease causality of these sequence variants is much more challenging since many of the genes identified are novel to development. Therefore, initial analysis requires a validation step. Here we present a high throughput strategy for CHD research aimed at the discovery of causative genes and underlying developmental mechanisms. Methods: Our goal is to use the small animal model, Xenopus tropicalis, to test candidate genes for effects on cardiac development. Xenopus is rapid and inexpensive allowing us to test many genes efficiently. To visualize abnormal cardiac structure, clinical cardiologists employ various imaging modalities. Similarly we sought to develop imaging methods for Xenopus cardiac phenotyping, which requires micro-scale imaging. We have applied optic coherence tomography and a novel hemoglobin contrast subtraction angiography to demonstrate high resolution, high-speed, in vivo cardiac phenotyping in Xenopus. (Approved by Yale Animal Care and Use Committee). Results: Our method identified a novel gene, CRP3, in a patient with non-compaction cardiomyopathy and AV canal defect. When depleted in Xenopus, we discovered a cardiac phenotype including loss of trabeculations, compact-small ventricle and enlarged atria, resembling the human phenotype closely. Conclusions: Our model and strategy aims to discover the causes of CHDs from patients that we see in the Pediatric/Neonatal Intensive Care Units.