Autopsy findings in siblings with hypertrophic cardiomyopathy caused by Arg92Trp mutation in the cardiac troponin T gene showing dilated cardiomyopathy-like features

Background: Hypertrophic cardiomyopathy (HCM) is caused by mutations in the genes that encode sarcomeric proteins. Although some patients with HCM have shown dilated cardiomyopathy (DCM)-like features, the relationship, between genotype and histologic findings is not well known. Hypothesis: Family members with the same gene mutation may show the same histopathologic changes and clinical manifestations. Methods: Siblings with HCM caused by an Arg92Trp mutation in the cardiac troponin T gene, showing DCM-like features, were examined. Results: The patients were a 69-year-old woman and her 57-year-old brother who both died from congestive heart failure. Their autopsies revealed the same histopathologic findings in the heart. The anterior walls and interventricular septa of their hearts were replaced with extensive fibrosis and showed thinning. Myocyte hypertrophy, disarray, and thickened medial walls of the. intramural coronary arteries were found. On electron microscopy, the number of mitochondria was seen to be increased and they formed many clusters. Conclusions: Patients with HCM caused by an Arg92Trp mutation in the cardiac troponin T gene may have the same histopathologic findings, which may result in DCM-like features.