Genetic Profiling and Phenotype Spectrum in a Chinese Cohort of Pediatric Cardiomyopathy Patients

This study examines pediatric cardiomyopathies by analyzing genetic and clinical data from 55 patients (2021–2024) at Beijing Anzhen Hospital. Four subtypes were studied: dilated (DCM, 24), hypertrophic (HCM, 22), arrhythmogenic right ventricular (ARVC, 7), and restrictive (RCM, 2). Clinical data, imaging, labs, and family histories were collected, with whole-exome sequencing (WES) identifying disease-causing variants classified via ACMG guidelines. Statistical analysis revealed a median age of 11 years, a proportion of 58% male participants, and ethnic diversity (21 northern Han, 29 southern Han, 5 minorities). In the cohort, 13 cases had an LVEF below 35%. Pathogenic/likely pathogenic (P/LP) variants were found in 21.8% of the patients, and variants of uncertain significance (VUS) were present in 38.2%, with MYH7 (seven cases) and MYBPC3 (five) being the most common. The WES positivity rates varied, at 58.3% (DCM), 72.7% (HCM), and 33.3% (ARVC/RCM). DCM patients with P/LP/VUS variants showed better contractile function (Fractional Shortening: 29.0% vs. 16.5%, p = 0.008). Females in the DCM group had poorer cardiac function (lower LVEF, higher LVESd, lower cardiac output) compared to males, with more females (nine vs. three) exhibiting an LVEF < 35% (p = 0.041). No significant gender differences were observed in the HCM cases. These findings highlight genotype–phenotype correlations and underscore the need for early intervention in female DCM patients.