# Investigating the multifactorial origins of congenital heart disease

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA-IRVINE · 2020 · $532,195

## Abstract

PROJECT SUMMARY
Congenital heart disease (CHD) is genetically complex, with most cases likely reflecting combined effects of
variation at multiple genes. Current methods, both statistical and experimental, for discovering causal alleles
of genes that produce disease phenotypes only in combination, are very limited. These limitations are a major
reason why the genetic origins of most CHD remain unknown, and there is a pressing need to overcome them.
To address this need, we propose a novel approach, which exploits genetic syndromes known as
“transcriptomopathies,” in which transcription is globally, yet subtly, disrupted. In one of these, Cornelia de
Lange Syndrome (CdLS), small changes (mostly <1.5-fold) occur in transcript levels for up to 1,000 genes in
each cell. This results in a reproducible spectrum of birth defects that includes CHD. CdLS is most commonly
caused by haploinsufficiency for NIPBL, a gene that encodes a cohesin-regulatory protein, and mouse and
zebrafish models of Nipbl-haploinsufficiency replicate CdLS phenotypes. Such animal models provide a
means to identify how sets of perturbations to gene expression which do not individually cause disease, can
act collectively to produce heart defects—thus modeling the multi-genic causation of CHD. Our investigation of
such models suggests that causal events likely occur early in embryogenesis during the initial morphogenesis
of the heart.
Recently, using mouse models in which Nipbl-haploinsufficiency can be switched on and off in different
embryonic cell lineages, we discovered that risk for atrial septal defects (ASDs), the main form of CHD in
Nipbl+/- mice, is controlled by non-additive interactions between gene expression changes in cardiomyocytes
and their progenitors; cells derived from endoderm, endocardium or endothelium; and cells of the rest of the
embryo. We now propose to exploit the genetic manipulability of this system to identify both the
morphogenetic abnormalities and the individual gene expression changes that collectively produce ASDs. By
analyzing early morphogenesis in globally- and conditionally-mutant embryos we will test several hypotheses
concerning the role of progenitor cell proliferation, patterning and migration, with a particular focus on the
progenitors of the second heart field, which preliminary results suggest may be central to ASD causation. By
using a variety of Cre recombinase-expressing mice to conditionally create, and rescue, Nipbl-
haploinsufficiency in a variety of lineages, we will investigate the roles of distinct subpopulations of cells in both
increasing and decreasing ASD risk. Finally, we will use single-cell RNA sequencing of early embryos to
identify gene expression changes associated with Nipbl-haploinsufficiency in those cells responsible for
causing ASDs. The result of these studies will be to develop novel, directly testable hypotheses about
mechanisms that underlie multifactorial, and multi-genic, CHD.

## Key facts

- **NIH application ID:** 9939679
- **Project number:** 5R01HL138659-04
- **Recipient organization:** UNIVERSITY OF CALIFORNIA-IRVINE
- **Principal Investigator:** ANNE LEIGHTON CALOF
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $532,195
- **Award type:** 5
- **Project period:** 2017-08-15 → 2023-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9939679

## Citation

> US National Institutes of Health, RePORTER application 9939679, Investigating the multifactorial origins of congenital heart disease (5R01HL138659-04). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/9939679. Licensed CC0.

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