Molecular and Functional Characterization of Rare CACNA1C Variants in Sudden Unexplained Death in the Young

Congenit Heart Dis. 2016 Dec;11(6):683-692. doi: 10.1111/chd.12371. Epub 2016 May 24.


Introduction: Perturbations in the CACNA1C-encoded L-type calcium channel α-subunit have been linked recently to heritable arrhythmia syndromes, including Timothy syndrome, Brugada syndrome, early repolarization syndrome, and long QT syndrome. These heritable arrhythmia syndromes may serve as a pathogenic basis for autopsy-negative sudden unexplained death in the young (SUDY). However, the contribution of CACNA1C mutations to SUDY is unknown.

Objective: We set out to determine the spectrum, prevalence, and pathophysiology of rare CACNA1C variants in SUDY.

Methods: Mutational analysis of CACNA1C was conducted in 82 SUDY cases using polymerase chain reaction, denaturing high-performance liquid chromatography, and direct sequencing. Identified variants were engineered using site-directed mutagenesis, and heterologously expressed in TSA-201 or HEK293 cells.

Results: Two SUDY cases (2.4%) harbored functional variants in CACNA1C. The E850del and N2091S variants involve highly conserved residues and localize to the II-III linker and C-terminus, respectively. Although observed in publically available exome databases, both variants confer abnormal CaV 1.2 electrophysiological characteristics. Examination of the electrophysiological properties revealed the E850del mutation in CACNA1C led to a 95% loss-of-function in ICa , and the N2091S variant led to a 105% gain-of-function in ICa. Additionally, N2091S led to minor kinetic alterations including a -3.4 mV shift in V1/2 of activation.

Conclusion: This study provides molecular and functional evidence that rare CACNA1C genetic variants may contribute to the underlying pathogenic basis for some cases of SUDY in either a gain or loss-of-function mechanism.

Keywords: Arrhythmia; CACNA1C; Genetics; Ion Channels; Pediatrics; Sudden Death.

MeSH terms

  • Adolescent
  • Adult
  • Age Factors
  • Arrhythmias, Cardiac / diagnosis
  • Arrhythmias, Cardiac / genetics*
  • Arrhythmias, Cardiac / mortality
  • Arrhythmias, Cardiac / physiopathology
  • Calcium Channels, L-Type / genetics*
  • Calcium Channels, L-Type / metabolism
  • Child
  • Child, Preschool
  • DNA Mutational Analysis
  • Death, Sudden, Cardiac / etiology*
  • Female
  • Genetic Predisposition to Disease
  • HEK293 Cells
  • Humans
  • Infant
  • Kinetics
  • Male
  • Membrane Potentials
  • Mutagenesis, Site-Directed
  • Mutation*
  • Patch-Clamp Techniques
  • Phenotype
  • Risk Factors
  • Transfection
  • Young Adult


  • CACNA1C protein, human
  • Calcium Channels, L-Type