A mouse model of conduction system patterning abnormalities in heterotaxy syndrome
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Updated: Jun 11, 2026
A Pipeline to Characterize Structural Heart Defects in the Fetal Mouse
Published on: December 16, 2022
Richard J Czosek1, Allison Haaning, Stephanie M Ware
1Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, Ohio 45229, USA.
Insights
A Zic3 mouse model reveals how disrupted embryonic left-right patterning causes cardiac conduction system abnormalities in heterotaxy syndrome. This finding aids understanding of congenital heart defects.
Area of Science:
- Developmental Biology
- Cardiovascular Science
- Genetics
Background:
- Heterotaxy syndrome involves disrupted left-right body patterning, often leading to congenital heart defects.
- Abnormalities in the cardiac conduction system are common in heterotaxy but their developmental origins are unclear.
Purpose of the Study:
- To investigate if a mouse model of X-linked heterotaxy (Zic3 null) replicates cardiac conduction system defects seen in human patients.
- To understand the mechanistic link between embryonic patterning defects and cardiac conduction system malformations.
Main Methods:
- Evaluation of cardiac structure and conduction system patterning in Zic3 null mouse embryos from embryonic day 9.5 to 16.5.
- Utilized genetic and molecular techniques to analyze developmental abnormalities.
Main Results:
- Zic3 null embryos exhibited severe structural heart abnormalities affecting atrial, ventricular, and conotruncal development.
- A spectrum of disorganized conduction system arrangements, including duplications, was observed.
- Abnormalities correlated with the severity and location of structural heart disease and were present early in development.
Conclusions:
- The Zic3 mouse model effectively recapitulates heterotaxy-associated cardiac conduction system abnormalities.
- This model is valuable for studying the mechanisms underlying conduction system patterning and its relationship to cardiovascular malformations.
- Findings may improve understanding and risk assessment for congenital heart defects in heterotaxy patients.
Abstract:
Duplication or absence of parts of the specialized cardiac conduction system in patients with heterotaxy syndrome causes significant clinical disease, but the mechanistic basis by which embryonic disruption of left-right patterning alters conduction system patterning in these patients is not well understood. We sought to determine whether a mouse model of X-linked human heterotaxy recapitulates conduction system abnormalities identified in patients with heterotaxy. Cardiac structure and conduction system patterning were evaluated in Zic3 null embryos from e9.5 to e16.5 using genetic and molecular methods. Severe structural abnormalities involving atrial, ventricular, and conotruncal development were associated with a spectrum of disorganized and ambiguous arrangements throughout the conduction system, including the appearance of duplicated structures. The severity and location of conduction system abnormalities correlated with the severity and location of associated structural heart disease and were identifiable at the earliest stages examined. The Zic3 mouse model provides a novel tool to dissect the mechanistic underpinnings of conduction system patterning and dysfunction and its relationship to cardiovascular malformations, making it a promising model to improve understanding and risk assessment in the clinical arena.
