Autosomal Recessive Cardiomyopathy Presenting as Acute Myocarditis

J Am Coll Cardiol. 2017 Apr 4;69(13):1653-1665. doi: 10.1016/j.jacc.2017.01.043.

Abstract

Background: Myocarditis is inflammation of the heart muscle that can follow various viral infections. Why children only rarely develop life-threatening acute viral myocarditis (AVM), given that the causal viral infections are common, is unknown. Genetic lesions might underlie such susceptibilities. Mouse genetic studies demonstrated that interferon (IFN)-α/β immunity defects increased susceptibility to virus-induced myocarditis. Moreover, variations in human TLR3, a potent inducer of IFNs, were proposed to underlie AVM.

Objectives: This study sought to evaluate the hypothesis that human genetic factors may underlie AVM in previously healthy children.

Methods: We tested the role of TLR3-IFN immunity using human induced pluripotent stem cell-derived cardiomyocytes. We then performed whole-exome sequencing of 42 unrelated children with acute myocarditis (AM), some with proven viral causes.

Results: We found that TLR3- and STAT1-deficient cardiomyocytes were not more susceptible to Coxsackie virus B3 (CVB3) infection than control cells. Moreover, CVB3 did not induce IFN-α/β and IFN-α/β-stimulated genes in control cardiomyocytes. Finally, exogenous IFN-α did not substantially protect cardiomyocytes against CVB3. We did not observe a significant enrichment of rare variations in TLR3- or IFN-α/β-related genes. Surprisingly, we found that homozygous but not heterozygous rare variants in genes associated with inherited cardiomyopathies were significantly enriched in AM-AVM patients compared with healthy individuals (p = 2.22E-03) or patients with other diseases (p = 1.08E-04). Seven of 42 patients (16.7%) carried rare biallelic (homozygous or compound heterozygous) nonsynonymous or splice-site variations in 6 cardiomyopathy-associated genes (BAG3, DSP, PKP2, RYR2, SCN5A, or TNNI3).

Conclusions: Previously silent recessive defects of the myocardium may predispose to acute heart failure presenting as AM, notably after common viral infections in children.

Keywords: cardiomyocytes; children; genetics; immunity; sequencing; virus.

MeSH terms

  • Cardiomyopathies / complications
  • Cardiomyopathies / genetics*
  • Case-Control Studies
  • Enterovirus B, Human / physiology*
  • Female
  • Host-Pathogen Interactions / genetics
  • Humans
  • Induced Pluripotent Stem Cells
  • Male
  • Myocarditis / genetics*
  • Myocarditis / virology
  • Myocytes, Cardiac / virology
  • STAT1 Transcription Factor / genetics*
  • Toll-Like Receptor 3 / genetics*

Substances

  • STAT1 Transcription Factor
  • STAT1 protein, human
  • TLR3 protein, human
  • Toll-Like Receptor 3