Primary cilia defects causing mitral valve prolapse

Area of Science:

• Cardiovascular Biology
• Developmental Biology
• Genetics

Background:

• Mitral valve prolapse (MVP) affects 1 in 40 individuals and is a leading cause of mitral valve surgery.
• The underlying causes of MVP, which can lead to arrhythmias, heart failure, and sudden cardiac death, remain poorly understood.
• Primary cilia are crucial cellular organelles whose role in MVP pathogenesis has not been previously established.

Purpose of the Study:

• To investigate the role of primary cilia genes and their associated pathways in the etiology of familial and sporadic nonsyndromic mitral valve prolapse.
• To elucidate the developmental mechanisms by which primary cilia influence mitral valve structure and function.

Main Methods:

• Expression studies and genetic ablation experiments in model systems to assess primary cilia function during cardiac development.
• Analysis of a large family with inherited MVP to identify causative genetic mutations.
• Generation and characterization of a mouse model harboring a specific cilia gene mutation.
• Pathway enrichment analysis of genome-wide association study (GWAS) data from MVP patients and controls.

Main Results:

• Primary cilia are essential for regulating extracellular matrix (ECM) deposition during cardiac development.
• Loss of primary cilia function leads to progressive myxomatous degeneration and severe mitral valve pathology in adult models.
• A mutation in the cilia gene DZIP1 was identified in a family with inherited MVP, and a mouse model confirmed its pathogenicity and association with myxomatous valve disease.
• GWAS data analysis confirmed the significant involvement of primary cilia genes in common forms of MVP.

Conclusions:

• Primary cilia play a critical role in the developmental regulation of the mitral valve through cilia-dependent ECM control.
• Defects in primary cilia genes represent a novel causative factor for mitral valve prolapse in both familial and sporadic cases.
• This research establishes a new developmental etiology for MVP, highlighting primary cilia as potential therapeutic targets.