Sex and Age Specific Genetic Risk Across the Dilated and Arrhythmogenic Cardiomyopathy Spectrum: Insights From the SHaRe Registry

Background: Dilated cardiomyopathy (DCM) and arrhythmogenic cardiomyopathy (ACM) are progressive cardiac muscle disorders with phenotypic and genetic overlap. Although a male predominance is noted in DCM/ACM, it remains unclear whether this extends to specific genetic subtypes or reflects variation in disease stage and whether sex influences age-dependent disease onset across pediatric and adult groups. Objectives: The aim of this study was to define sex-based differences in genetic architecture and age at diagnosis of DCM/ACM across pediatric and adult populations. Methods: Genetically tested adult and pediatric DCM/ACM patients and asymptomatic genotype-positive relatives enrolled in the multicenter SHaRe (Sarcomeric Human Cardiomyopathy Registry) were analyzed. Sex distribution across 27 DCM- and ACM-associated genes was evaluated using logistic regression. Age at diagnosis was compared across sex and genes using Kaplan-Meier cumulative incidence estimates. Results: Among 3,410 patients, a 61% male predominance was present across subgroups of genotype positive, genotype negative, and variants of uncertain significance (P = 0.008), with significant gene-specific variation. TTN truncating variants (TTNtv) were less common in females (OR: 0.42 [95% CI: 0.33-0.54]; P < 0.01), while DSP (OR: 3.3 [95% CI: 2.35-4.78]; P < 0.01) and grouped non-TTN sarcomeric variants (ACTC1, TNNT2, MYH7, TNNC1, TNNI3, and TPM1) were more common (OR: 1.68 [95% CI: 1.15-2.47]; P < 0.001) in females compared with males with DCM/ACM. Age at diagnosis was comparable between sexes, except in TTNtv carriers, among whom males exhibited earlier disease onset compared with females (median age 45 years [Q1-Q3: 33-55 years] vs 51 years [Q1-Q3: 38-60 years]; P = 0.003). Pediatric-onset (diagnosis at <18 years) cases (n = 174) also demonstrated a male predominance (60% male) but had distinct genetic characteristics, with non-TTN sarcomeric and PKP2 variants being more prevalent compared with adult-onset disease (non-TTN sarcomeric OR: 5.5 [95% CI: 3.3-8.9; P < 0.01]; PKP2 OR: 2.8 [95% CI: 1.1-5.2; P < 0.05]) and a bimodal age at onset peaking in infancy and adolescence. Conclusions: Gene-specific sex differences influence disease prevalence and age at onset in DCM/ACM. TTNtv are more common with earlier onset in males, whereas DSP and non-TTN sarcomeric variants predominate in females. Pediatric-onset DCM/ACM is genetically distinct and caused predominantly by non-TTN sarcomeric variants, especially during infancy. These findings support age- and sex-informed surveillance strategies and prioritize future research into the mechanisms of observed sex-based differences.