44/Characterisation of missense variants in RYR2

The rare monogenic arrhythmogenic disorder catecholaminergic polymorphic ventricular tachycardia (CPVT) is characterised by episodic ventricular dysrhythmia triggered by exercise or emotion in individuals without structural cardiac defects. Next generation sequencing has now become more widely accessible and RYR2 in its entirety can be screened relatively easily. This has led to an increase in the number of RYR2 variants being reported in individuals with cardiac dysrhythmia. The majority of RYR2 variants are missense changes that lead to increased channel activity and the rarity of these variants makes it difficult to determine their pathogenicity, thus the majority are classified as being of unknown significance (VUS). We collated RYR2 variants reported in individuals with or suspected of having CPVT and classified them using a statistical method and the ACMG guidelines. Where possible the phenotype associated with each variant was recorded to determine any genotype-phenotype correlations. Recently RYR2 variants have also been shown to cause ventricular arrhythmias by a loss of function mechanism. We used five computational splice prediction tools and an ex vivo splicing assay to investigate whether 329 rare variants in RYR2 from a cohort of individuals undergoing genetic testing for a ventricular arrhythmia alter splicing. Ten RYR2 variants were predicted to disrupt splicing by multiple computational tools. Of these, none altered splicing in an ex vivo splicing assay.