Background: The spectrum of genetic variants and their clinical significance of Hypertrophic cardiomyopathy (HCM) have been poorly studied in Asian patients. The objectives of this study were to assess the spectrum of genetic variants and genotype–phenotype relationships within a Korean HCM population. Methods: Eighty-nine consecutive unrelated HCM patients were included. All patients underwent genotypic analysis for 23 HCM-associated genes. Clinical parameters including echocardiographic and cardiac magnetic resonance (CMR) parameters were evaluated. A composite of major adverse cardiac and cerebrovascular events was assessed. Results: Genetic variants were detected in 55 of 89 subjects. Pathogenic variants or likely pathogenic variants were identified in 27 of HCM patients in MYBPC3, TNNI3, MYH7, and MYL7. Variants of uncertain significance were identified in 28 patients. There were significant differences in the presence of non-sustained ventricular tachycardia (p = 0.030) and myocardial fibrosis on CMR (p = 0.029) in the detected compared to the not-detected groups. Event-free survival was superior in the not-detected group (p = 0.006). Conclusion: Genetic variants in patients with HCM are relatively common and are associated with adverse clinical events and myocardial fibrosis on CMR. Genotypic analysis may add important information to clinical variables in the assessment of long-term risk for HCM patients.

Neurally mediated syncope (NMS) is a common clinical problem. The underlying genetic factors of NMS remain controversial. We hypothesized that cardiac syncope-related genes may contribute to NMS in patients with previous frequent syncopal episodes and/or a family history of syncope. A total of 54 consecutive patients diagnosed with NMS were prospectively enrolled between 2013 and 2016. Inclusion criteria were more than five syncopal episodes with a family history of syncope (n = 17) or more than five syncopal episodes with no family history of syncope (n = 37). Ninety-eight cardiac syncope-related genes (channelopathy: 43 genes, cardiomyopathy: 50 genes, primary pulmonary hypertension: 5 genes) were screened by exome sequencing. All identified variants were classified according to the standards and guidelines by the American College of Medical Genetics and Genomics and the Association for Molecular Pathology. Of the 54 patients, 17 patients (31.5%) had a family history of syncope. Two patients (3.7%) had pathogenic and likely pathogenic variants (PV/LPV) in cardiac syncope-related genes TTN and MYH7. We investigated genetic variation in patients with frequent NMS with a positive family history of syncope in Korea. PV/LPVs in genes related to cardiomyopathy were associated with recurrent NMS in Korean patients. Closer follow-up of these patients might be needed.