Genetic testing in the management of relatives of patients with hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy is the most common genetic cardiac disease with vast genetic heterogeneity. First-degree relatives of patients with HCM are at 50% risk of inheriting the disease-causing mutation. Genetic testing is helpful in identifying the relatives harbouring the mutations. When genetic testing is not available, relatives need to be examined regularly. We tested a cohort of 99 unrelated patients with HCM for mutations in MYH7, MYBPC3, TNNI3 and TNNT2 genes. In families with identified pathogenic mutation, we performed genetic and clinical examination in relatives to study the influence of genetic testing on the management of the relatives and to study the usefulness of echocardiographic criteria for distinguishing relatives with positive and negative genotype. We identified 38 genetic variants in 47 patients (47 %). Fifteen of these variants in 21 patients (21 %) were pathogenic mutations. We perReceived March 25, 2013. Accepted June 3, 2013. Supported by the project for conceptual development of research organization 00064203 (Ministry of Health, Czech Republic), grants NT 11401-5 and 9164/3 from the Internal Grant Agency, Ministry of Health, Czech Republic and grant UNCE 204010 from the Third Faculty of Medicine, Charles University in Prague, Czech Republic. Corresponding author: Pavol Tomasov, Department of Cardiology, Second Faculty of Medicine, Charles University in Prague and University Hospital Motol, V Uvalu 84, 150 06 Prague 5, Czech Republic. Phone: (+420) 224 434 901; Fax: (+420) 224 434 920; e-mail: pavol.tomasov@fnmotol.cz Abbreviations: ACCF/AHA – American College of Cardiology Foundation/American Heart Association, ASE – American Society of Echocardiography ECG – electrocardiogram, ESC – European Society of Cardiology, HCM – hypertrophic cardiomyopathy, LVH – left ventricular hypertrophy. formed genetic testing in 52 relatives (18 of them (35 %) yielding positive results). Genetic testing of one HCM patient allowed us to omit 2.45–5.15 future cardiologic examinations of the relatives. None of the studied echocardiographic criteria were significantly different between the relatives with positive and negative genotypes, with the exception of a combined echocardiographic score (genotype positive vs. genotype negative, 3.316 vs. -0.489, P = 0.01). As a conclusion, our study of HCM patients and their relatives confirmed the role of genetic testing in the management of the relatives and found only limited benefit of the proposed echocardiographic parameters in identifying disease-causing mutation carriers.