Redefining the Genetic Architecture of Hypertrophic Cardiomyopathy: Role of Intermediate-Effect Variants

Year: 2025

Type: article

Abstract: BACKGROUND: Hypertrophic cardiomyopathy (HCM) is a genetically heterogeneous disorder linked primarily to rare variants in sarcomeric genes, although recently certain nonsarcomeric genes have emerged as important contributors. Nonmendelian genetic variants with reproducible moderate-effect sizes and low penetrance, intermediate-effect variants (IEVs), can play a crucial role in modulating disease expression. Understanding the clinical impact of IEVs is crucial to unravel the complex genetic architecture of HCM. METHODS: We conducted an ancestry-based enrichment analysis of 14 validated HCM genes, including the 9 core sarcomeric and 5 nonsarcomeric genes (ALPK3 , CSRP3 , FHOD3 , FLNC , and TRIM63 ). Enrichment of intermediate frequency missense variants was evaluated in 10 981 patients with HCM, 4030 internal controls of European-ancestry, and 590 000 external controls from gnomAD non-Finnish Europeans. The population-attributable fraction was calculated to assess contribution of IEVs to HCM. Age-related disease penetrance, phenotypic severity (left ventricular maximum wall thickness), and major adverse cardiac events were analyzed in 11 991 HCM cases of the whole cohort according to 5 genetic groups: genotype negative, isolated IEV, monogenic, monogenic+IEV, and double monogenic. RESULTS: Fourteen IEVs in 8 genes were identified in 731 individuals (6.1% of the cohort), of whom 570 patients (4.8%) had IEVs in isolation: 198 (34.7%) in sarcomeric genes and 372 (65.3%) in nonsarcomeric genes. The contribution of IEVs to HCM genetics according to population-attributable fraction was estimated to be 4.9% (95% CI, 3.2–6.7). A significant gradient in penetrance, phenotypic severity, and major adverse cardiac events was observed across genetic groups. Compared with genotype-negative patients, IEV carriers displayed a younger median age at diagnosis (59 years of age [95% CI, 46–69] versus 61 years [95% CI, 49–70]; P =0.0073) and a higher mean left ventricular maximum wall thickness (18.1±3.7 versus 19.0±4.3; P =0.0043). IEVs also modified disease expression in individuals with monogenic variants, causing a more aggressive phenotype than in individuals from the monogenic-only group with HCM onset at younger age and a higher left ventricular maximum wall thickness (all P <0.0001), with major adverse cardiac event–free survival being significantly lower (93.3% versus 69.3% at 70 years of age; P <0.0001). CONCLUSIONS: IEVs are present in 6.1% of HCM cases and account for 4.8% of HCM genetic burden. IEVs also influence disease severity and outcomes, particularly when combined with monogenic disease-causing variants. Evaluation of IEVs should be considered when HCM genetic testing is performed.

Source: Circulation

DOI: 10.1161/circulationaha.125.074529

Institutions: Universidade da Coruña, Fundacion Favaloro Hospital Universitario, Favaloro Foundation, Hospital Universitario Virgen del Rocío, Centro de Investigación en Red en Enfermedades Cardiovasculares, Hospital Universitario Puerta de Hierro Majadahonda, Clinica Universidad de Navarra, Complexo Hospitalario Universitario A Coruña, Instituto de Investigación Biomédica de A Coruña, Complejo Hospitalario de Salamanca, Hospital Universitario 12 De Octubre, Xiamen Innovax Biotech Co., Ltd. (China), Amsterdam University Medical Centers, Amsterdam Cardiovascular Sciences, Hospital Universitario Virgen de la Arrixaca, Instituto de Investigación Biosanitaria de Granada, Marqués de Valdecilla University Hospital, British Heart Foundation, University College London, Hospital General Universitario de Ciudad Real, University of Castilla-La Mancha, University of Amsterdam, Spanish National Centre for Cardiovascular Research, St George's, University of London, City St George's, University of London

Language: English

Topic: Cardiomyopathy and Myosin Studies

Subfield: Cardiology and Cardiovascular Medicine

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: hybrid

Funders: Bristol-Myers Squibb, Sanofi, Alnylam Pharmaceuticals, Cytokinetics, European Commission, HORIZON EUROPE European Innovation Council

OpenAlex ID: W4413826364