Autosomal recessive catecholamine-induced polymorphic ventricular tachycardia.

Area of Science:

• Cardiology
• Genetics
• Molecular Biology

Background:

• Catecholamine-induced polymorphic ventricular tachycardia (PVT) presents with syncope, seizures, or sudden death, often in children with normal hearts.
• An autosomal recessive form of PVT was identified in Bedouin families, linked to chromosome 1p13-1p21.

Purpose of the Study:

• To identify the genetic cause of autosomal recessive PVT in affected families.
• To elucidate the functional consequences of the identified mutation on cardiac function.

Main Methods:

• Genetic linkage analysis in affected families.
• Direct sequencing of candidate genes within the linkage region, specifically CASQ2.
• Analysis of protein structure and function related to calcium handling.

Main Results:

• A novel mutation (Asp307His) was identified in the calsequestrin 2 (CASQ2) gene.
• This mutation alters a highly conserved, negatively charged residue in the CASQ2 protein, affecting calcium storage.
• CASQ2 is the primary cardiac calcium reservoir, suggesting a role in the disease pathophysiology.

Conclusions:

• The identified CASQ2 mutation is the likely cause of autosomal recessive PVT in these families.
• Disruption of intracellular calcium regulation by the CASQ2 mutation underlies the observed ventricular tachycardia.
• Targeting intracellular calcium control may offer therapeutic strategies for PVT patients.