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Cardiac troponin I (TNNI3, MIM+191044) gene mutations cause both restrictive and hypertrophic cardiomyopathies in children and adults. The p.[R204H] mutation in the TNNI3 gene was described as associated with hypertrophic cardiomyopathy phenotypes.
We identified this mutation in a young female patient with pure restrictive cardiomyopathy. She first came to clinical attention at the age of 14, after the sudden death of her 18-year-old brother who was an amateur athlete. She was asymptomatic and did not show cardiac morphofunctional abnormalities. At the age of 16, the echocardiographic evaluation showed a mild bi-atrial enlargement. During the next two years, she developed restrictive cardiomyopathy. She was initially given β-blockers and then angiotensin-converting enzyme inhibitors and diuretics. In the following years she had frequent episodes of diastolic heart failure and underwent several clinical and echocardiographic evaluations. The maximum left ventricular thickness was 13 mm (range 11–13). At the age of 22 she went on a heart transplant waiting list and came to our attention for genetic counselling and testing. After informed consent, according to internal protocol approved by the local ethics committee, we performed molecular genetic analysis of the genes that are more frequently associated with restrictive cardiomyopathy and hypertrophic cardiomyopathy. We identified the known p.R204H missense mutation in the TNNI3 gene.
At the age of 23, she underwent heart transplantation. Her heart showed normal ventricular thickness and absence of scars (panel A); the histopathological study showed myocyte disarray without significant hypertrophy (panel B). The mismatch disarray-lack of hypertrophy characterised this case of pure restrictive cardiomyopathy.
Funding: Supported by the Ricerca Corrente IRCCS Policlinico San Matteo and Fondazione Cariplo, Milano, Italy.
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