Cardiac troponin I mutations in Australian families with hypertrophic cardiomyopathy: clinical, genetic and functional consequences

Alessandra Doolan, Molly Tebo, Jodie Ingles, Lan Nguyen, Tatiana Tsoutsman, Lien Lam, Christine Chiu, Jessica Chung, Robert G. Weintraub, Christopher Semsarian*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

37 Citations (Scopus)

Abstract

Background. - Hypertrophic cardiomyopathy (HCM) is an autosomal dominant disorder caused by mutations in sarcomeric proteins. Cardiac troponin I (cTnI) is a key switch molecule in the sarcomere. Mutations in cTnI have been identified in <1% of genotyped HCM families. Methods. - To study the prevalence, clinical significance and functional consequences of cTnI mutations, genetic testing was performed in 120 consecutive Australian families with HCM referred to a tertiary referral centre, and results correlated with clinical phenotype. Each cTnI mutation identified was tested in a mammalian two-hybrid system to evaluate the functional effects of these mutations on troponin complex interactions. Results. - Disease-causing missense mutations were identified in four families (3.3%). Two mutations were located at the same codon in exon 7 (R162G, R162P), and two in exon 8 (L198P, R204H). All four mutations change amino acid residues which are highly conserved and were not found in normal populations. Follow-up family screening has identified a total of seven clinically affected members in these four families, with a further four members who carry the gene mutation but have no clinical evidence of disease. Age at clinical presentation was variable (range 15-68 years) and the mean septal wall thickness was 19.3 ± 4.6 mm (range 7-33 mm) in clinically affected individuals, including children. In all four families, at least one member had a sudden cardiac death event, including previous cardiac arrest, indicating a more malignant form of HCM. All four mutations disrupted functional interactions with troponin C and T and this may account for the increased severity of disease in these families. Conclusions. - Gene mutations in cTnI occur in Australian families with HCM with a prevalence higher than previously reported and may be associated with a clinically more malignant course, reflecting significant disruptions to troponin complex interactions.

Original languageEnglish
Pages (from-to)387-393
Number of pages7
JournalJournal of Molecular and Cellular Cardiology
Volume38
Issue number2
DOIs
Publication statusPublished - 1 Jan 2005
Externally publishedYes

Keywords

  • Cardiomyopathy
  • Hypertrophy
  • Interactions
  • Troponin complex
  • Troponin I

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