Familial Dilated Cardiomyopathy Caused by an Alpha-Tropomyosin Mutation. The Distinctive Natural History of Sarcomeric Dilated Cardiomyopathy

Neal K. Lakdawala, Lisa Dellefave, Charles S. Redwood, Elizabeth Sparks, Allison L. Cirino, Steve Depalma, Steven D. Colan, Birgit Funke, Rebekah S. Zimmerman, Paul Robinson, Hugh Watkins, Christine E. Seidman, J. G. Seidman, Elizabeth M. McNally, Carolyn Y. Ho*

*Corresponding author for this work

Research output: Contribution to journalArticle

79 Scopus citations

Abstract

Objectives: We sought to further define the role of sarcomere mutations in dilated cardiomyopathy (DCM) and associated clinical phenotypes. Background: Mutations in several contractile proteins contribute to DCM, but definitive evidence for the roles of most sarcomere genes remains limited by the lack of robust genetic support. Methods: Direct sequencing of 6 sarcomere genes was performed on 334 probands with DCM. A novel D230N missense mutation in the gene encoding alpha-tropomyosin (TPM1) was identified. Functional assessment was performed by the use of an in vitro reconstituted sarcomere complex to evaluate ATPase regulation and Ca2+ affinity as correlates of contractility. Results: TPM1 D230N segregated with DCM in 2 large unrelated families. This mutation altered an evolutionarily conserved residue and was absent in >1,000 control chromosomes. In vitro studies demonstrated major inhibitory effects on sarcomere function with reduced Ca2+ sensitivity, maximum activation, and Ca2+ affinity compared with wild-type TPM1. Clinical manifestations ranged from decompensated heart failure or sudden death in those presenting early in life to asymptomatic left ventricular dysfunction in those diagnosed during adulthood. Notably, several affected infants had remarkable improvement. Conclusions: Genetic segregation in 2 unrelated families and functional analyses conclusively establish a pathogenic role for TPM1 mutations in DCM. In vitro results demonstrate contrasting effects of DCM and hypertrophic cardiomyopathy mutations in TPM1, suggesting that specific functional consequences shape cardiac remodeling. Along with previous reports, our data support a distinctive, age-dependent phenotype with sarcomere-associated DCM where presentation early in life is associated with severe, sometimes lethal, disease. These observations have implications for the management of familial DCM.

Original languageEnglish (US)
Pages (from-to)320-329
Number of pages10
JournalJournal of the American College of Cardiology
Volume55
Issue number4
DOIs
StatePublished - Jan 26 2010

Keywords

  • cardiomyopathy
  • genetics
  • heart failure

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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    Lakdawala, N. K., Dellefave, L., Redwood, C. S., Sparks, E., Cirino, A. L., Depalma, S., Colan, S. D., Funke, B., Zimmerman, R. S., Robinson, P., Watkins, H., Seidman, C. E., Seidman, J. G., McNally, E. M., & Ho, C. Y. (2010). Familial Dilated Cardiomyopathy Caused by an Alpha-Tropomyosin Mutation. The Distinctive Natural History of Sarcomeric Dilated Cardiomyopathy. Journal of the American College of Cardiology, 55(4), 320-329. https://doi.org/10.1016/j.jacc.2009.11.017