Penetrance and expressivity of the R858H CACNA1C variant in a five-generation pedigree segregating an arrhythmogenic channelopathy

R. J. Mc Kinlay Gardner, Ian G. Crozier, Alex L. Binfield, Donald R. Love, Klaus Lehnert, Kate Gibson, Caroline J. Lintott, Russell G. Snell, Jessie C. Jacobsen, Peter P. Jones, Kathryn E. Waddell-Smith, Martin A. Kennedy, Jonathan R. Skinner, The Cardiac Inherited Diseases Group

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Background: Isolated cardiac arrhythmia due to a variant in CACNA1C is of recent knowledge. Most reports have been of singleton cases or of quite small families, and estimates of penetrance and expressivity have been difficult to obtain. We here describe a large pedigree, from which such estimates have been calculated. Methods: We studied a five-generation family, in which a CACNA1C variant c.2573G>A p.Arg858His co-segregates with syncope and cardiac arrest, documenting electrocardiographic data and cardiac symptomatology. The reported patients/families from the literature with CACNA1C gene variants were reviewed, and genotype–phenotype correlations are drawn. Results: The range of phenotype in the studied family is wide, from no apparent effect, through an asymptomatic QT interval prolongation on electrocardiography, to episodes of presyncope and syncope, ventricular fibrillation, and sudden death. QT prolongation showed inconsistent correlation with functional cardiology. Based upon analysis of 28 heterozygous family members, estimates of penetrance and expressivity are derived. Conclusions: These estimates of penetrance and expressivity, for this specific variant, may be useful in clinical practice. Review of the literature indicates that individual CACNA1C variants have their own particular genotype–phenotype correlations. We suggest that, at least in respect of the particular variant reported here, “arrhythmogenic channelopathy” may be a more fitting nomenclature than long QT syndrome.

Original languageEnglish
Article numbere00476
Number of pages12
JournalMolecular Genetics and Genomic Medicine
Volume7
Issue number1
DOIs
Publication statusPublished - 20 Feb 2019
Externally publishedYes

Bibliographical note

This is an open access article under the terms of the Creative Commons Attribution License (CC BY), which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Keywords

  • arrhythmia
  • CACNA1C
  • expressivity
  • long QT
  • penetrance

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