Hypertrophic cardiomyopathy (HCM) is an inherited disease with genetic and phenotypic variability and an unclear genotype-clinical course relationship. The aim of our study was to assess the phenotypic and molecular characteristics of patients with HCM.Clinical and genetic data from adult HCM patients treated at a university hospital between 2005 and 2024 were analysed. A comparative analysis of probands with a single pathogenic/likely pathogenic (P/LP) variant and without a P/LP variant was performed.The analysis involved 214 individuals with HCM, 42.1% being females. The median age at HCM diagnosis was 52 (38-62) years. P/LP variants were identified in 92 (43.0%) individuals. Compared to patients without an identified genetic cause, individuals with P/LP variants had a significantly earlier HCM diagnosis (43.5 (32.3-58.0) vs. 54.0 (45.8-65.0) years, p < 0.001) and higher maximal thickness on cardiac imaging (17.5 (15.0-21.0) vs. 17.0 (15.0-19.0) mm, p = 0.009 on transthoracic echocardiography and 21.0 (18.0-23.0) vs. 18.0 (16.0-20.0) mm, p < 0.001 on cardiac magnetic resonance imaging). During the median follow-up of 4.2 (1.6-6.8) years, individuals with P/LP HCM variants had earlier onset of atrial fibrillation (p = 0.021), ventricular tachycardia (p = 0.004), heart failure composite (p = 0.006), and overall composite outcome (p = 0.002). No difference between the groups was observed when hazard ratios for clinical outcomes were adjusted by age at HCM diagnosis and gender.Genotype influences HCM phenotype, as patients with P/LP variants experience earlier onset and more pronounced hypertrophy. However, once diagnosed, genotype may not predict the outcomes of HCM.