Sudden death due to troponin T mutations

Area of Science:

• Cardiovascular Genetics
• Molecular Cardiology
• Genetic Diseases

Background:

• Hypertrophic cardiomyopathy is a leading cause of sudden cardiac death in young individuals, often with a familial inheritance pattern.
• Mutations in contractile protein genes are implicated in familial hypertrophic cardiomyopathy, suggesting potential for genetic screening.
• Previous findings indicated cardiac troponin T gene mutations are linked to poor prognosis and mild hypertrophy, necessitating further investigation due to genotype-phenotype variability.

Purpose of the Study:

• To validate initial findings on the clinical and prognostic characteristics of hypertrophic cardiomyopathy associated with cardiac troponin T gene mutations.
• To further analyze cardiac troponin T mutations given the variability observed in genotype-phenotype correlations.

Main Methods:

• Screening of deoxyribonucleic acid from hypertrophic cardiomyopathy patients for cardiac troponin T mutations using a ribonuclease protection assay.
• Utilizing polymerase chain reaction-based detection to genotype members of two pedigrees carrying a novel mutation.
• Conducting echocardiography, electrocardiology, and obtaining family histories for gene carriers.

Main Results:

• Identification of a novel cardiac troponin T gene mutation (arginine 92 tryptophan) in 19 out of 48 members across two pedigrees.
• The clinical phenotype exhibited minimal hypertrophy (mean maximal ventricular wall thickness 11.3 +/- 5.4 mm) and low clinical penetrance (40% by echocardiography).
• A high incidence of sudden cardiac death was observed, with a mean age of 17 +/- 9 years.

Conclusions:

• Diverse cardiac troponin T gene mutations consistently result in a specific disease phenotype.
• This phenotype is associated with a poor prognosis, despite mild or undetectable hypertrophy.
• Genotyping for cardiac troponin T mutations is highly informative for patient management and genetic counseling.