Exon 3 deletion of RYR2 encoding cardiac ryanodine receptor is associated with left ventricular non-compaction

Abstract

Aims: Ryanodine receptor gene (RYR2) mutations are well known to cause catecholaminergic polymorphic ventricular tachycardia (CPVT). Recently, RYR2 exon 3 deletion has been identified in patients with dilated cardiomyopathy (DCM) and/or CPVT. This study aimed to screen for the RYR2 exon 3 deletion in CPVT probands, characterize its clinical pathology, and confirm the genomic rearrangement.

Methods and results: Our cohort consisted of 24 CPVT probands. Polymerase chain reaction (PCR)-based conventional genetic analysis did not identify any mutations in coding exons of RYR2 in these probands. They were screened using multiplex ligation-dependent probe amplification (MLPA). In probands identified with RYR2 exon 3 deletion, the precise location of the deletion was identified by quantitative PCR and direct sequencing methods. We identified two CPVT probands from unrelated families who harboured a large deletion including exon 3. The probands were 9- and 17-year-old girls. Both probands had a history of syncope related to emotional stress or exercise, exhibited bradycardia, and were diagnosed with left ventricular non-compaction (LVNC). We examined 10 family members and identified six more RYR2 exon 3 deletion carriers. In total, there were eight carriers, of which seven were diagnosed with LVNC (87.5%). Two carriers under the age of 4 years remained asymptomatic, although they were diagnosed with LVNC. Using quantitative PCR and direct sequencing, we confirmed that the deletions were 1.1 and 37.7 kb in length.

Conclusion: RYR2 exon 3 deletion is frequently associated with LVNC. Therefore, detection of the deletion offers a new modality for predicting the prognosis of patients with LVNC with ventricular/atrial arrhythmias, particularly in children.

Keywords: Bradycardia; Catecholaminergic polymorphic ventricular tachycardia; Genetic screening; Left ventricular non-compaction; Multiplex ligation-dependent probe amplification; RYR2 exon 3 deletion.