A type 2 ryanodine receptor variant associated with reduced Ca 2+ release and short-coupled torsades de pointes ventricular arrhythmia

Heart Rhythm. 2017 Jan;14(1):98-107. doi: 10.1016/j.hrthm.2016.10.015. Epub 2016 Oct 15.

Abstract

Background: Ventricular fibrillation may be caused by premature ventricular contractions (PVCs) whose coupling intervals are <300 ms, a characteristic of the short-coupled variant of torsades de pointes (scTdP).

Objective: The purpose of this study was to analyze the underlying cardiac ryanodine receptor (RyR2) variants in patients with scTdP.

Methods: Seven patients with scTdP (mean age 34 ± 12 years; 4 men and 3 women) were enrolled in this study. The RyR2 gene was screened by targeted gene sequencing methods; variant minor allele frequency was confirmed in 3 databases; and the pathogenicity was investigated in silico analysis using multiple tools. The activity of wild-type and mutant RyR2 channels was evaluated by monitoring Ca2+ signals of HEK293 cells with a [3H]ryanodine binding assay.

Results: The mean coupling interval of PVCs was 282 ± 13 ms. The 12-lead electrocardiogram had no specific findings except PVCs with an extremely short-coupling interval. Genetic analysis revealed 3 novel RyR2 variants and 1 polymorphism, all located in the cytoplasmic region. p.Ser4938Phe was not detected in 3 databases, and in silico analysis indicated its pathogenicity. In functional analysis, p.Ser4938Phe demonstrated loss of function and impaired RyR2 channel Ca2+ release, while 2 other variants, p.Val1024Ile and p.Ala2673Val, had mild gain-of-function effects but were similar to the polymorphism p.Asn1551Ser.

Conclusion: We identified an RyR2 variant associated with reduced Ca2+ release and short-coupled torsades de pointes ventricular arrhythmia. The mechanisms of arrhythmogenesis remain unclear.

Keywords: Catecholaminergic polymorphic ventricular tachycardia; Idiopathic ventricular fibrillation; Long QT; RyR2; Torsades de pointes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Calcium Channels / metabolism*
  • DNA Mutational Analysis
  • Electrocardiography
  • Female
  • Gene Expression Regulation*
  • Genetic Variation*
  • Humans
  • Incidence
  • Male
  • Middle Aged
  • Prognosis
  • Risk Assessment
  • Ryanodine Receptor Calcium Release Channel / genetics*
  • Sampling Studies
  • Survival Rate
  • Tachycardia, Ventricular / epidemiology
  • Tachycardia, Ventricular / genetics*
  • Tachycardia, Ventricular / physiopathology
  • Torsades de Pointes / epidemiology
  • Torsades de Pointes / genetics*
  • Torsades de Pointes / physiopathology
  • Young Adult

Substances

  • Calcium Channels
  • Ryanodine Receptor Calcium Release Channel