Cardiomyopathy-Associated Pathogenic Variants in Pediatric Myocarditis: A Study From the Pediatric Cardiomyopathy Registry

BACKGROUND: Studies have demonstrated that patients with myocarditis may have a higher burden of cardiomyopathy-associated genetic variants than the general population. However, data on children are limited. We compared the prevalence of rare predicted-damaging variants and clinically pathogenic variants in children with dilated cardiomyopathy (DCM) secondary to myocarditis with that in children with DCM alone and in heart-healthy controls. METHODS: Children with DCM secondary to myocarditis and children with DCM alone who underwent exome sequencing as part of a prior cross-sectional study were identified in the Pediatric Cardiomyopathy Registry, a large multicenter registry of children with cardiomyopathy. Controls from the Indiana University Biobank were matched 4:1 with myocarditis cases on genomic similarity. Rare predicted-damaging variants in cardiomyopathy-associated genes were identified using a bioinformatics approach. Clinical guidelines were used to determine clinical pathogenicity. The prevalence of variants was compared across the 3 groups. RESULTS: There were 32 patients with DCM secondary to myocarditis. The prevalence of rare predicted-damaging variants was 34.4% (11/32 [95% CI, 18.6%–53.2%]) in cases compared with 6.3% (8/128 [95% CI, 2.7%–11.9%]) in controls ( P <0.001). Clinical review indicated all rare predicted-damaging variants in cases were pathogenic (1/12), likely pathogenic (3/12), or variants of uncertain significance (8/12), whereas most variants in controls were benign (2/8) or likely benign (4/8). The prevalence of pathogenic/likely pathogenic variants in cases was 12.5% (95% CI, 3.5%–29.0%) compared with 0% (95% CI, 0%–2.3%) in controls ( P <0.01). Rare predicted-damaging and clinically pathogenic/likely pathogenic variant prevalence was not significantly different in children with DCM secondary to myocarditis and DCM without myocarditis ( P =0.17 and P =1.00, respectively). CONCLUSIONS: Children with DCM secondary to myocarditis had a higher burden of variants in cardiomyopathy-associated genes than that of heart-healthy controls. Larger studies will be needed to determine the utility of routine genetic testing in this population.