👤 J Veselka

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 performed 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. Show less

Hypertrophic cardiomyopathy (HCM) is a cardiovascular disease with autosomal dominant inheritance. It is caused by mutations in the genes coding for structural and/or regulatory proteins found in the sarcomere of cardiomyocytes. A group of genes, including the heavy chain of beta-myosin (MYH7), myosin binding protein C (MYBPC3), cardiac troponin I (TNNI3) and cardiac troponin T (TNNT2) are frequently affected by causal mutations. While exact mutation frequency data has been obtained for various populations, no screening has been reported for Central European populations. We performed a complete sequencing of MYH7, MYBPC3, TNNI3 and TNNT2 genes in 100 HCM patients. We discovered mutations in a total of 40 patients (40%), including 4 patients with double mutations. A total of 35 different mutation types were detected, of which 17 were novel. The contributions from individual genes were: 24 mutations in MYBPC3 (54.5%), 14 in MYH7 (31.8%), 4 in TNNI3 (9%) and 2 mutations in TNNT2 (4.5%). We have observed a wide variability in disease manifestation across the different genes/mutation types. In addition, we have discovered differences in both frequency and distribution of mutations of the two most common genes (MYBPC3 and MYH7) compared to other populations. The most common gene responsible for HCM in our study population was MYBPC3, followed by MYH7, TNNI3 and TNNT2. Phenotypic heterogeneity, as well as the dissimilarity to other populations, prevents effective use of a pre-screening test, which would be directed at the most common mutation hotspots, in our population. Show less