Discerning From the Good, the Bad, and the Ugly
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Catecholaminergic polymorphic ventricular tachycardia (CPVT) is one of the most malignant inherited arrhythmias, with onset of symptoms in childhood and a 70% risk of experiencing a cardiac event before the age of 20 years if untreated.1 Presymptomatic diagnosis is challenging, because the resting ECG is normal, and a family history of adrenergic-related sudden cardiac death or syncope is only present in 30% of individuals.1 The hRyR2 gene, coding for the ryanodine receptor channel, has been linked to the autosomal dominant form of CPVT, and a mutation may be detected in ≈65% of probands.2 A rare autosomal recessive form, linked to CASQ2 homozygous mutations, has also been described.2 Additional genes have been linked to the phenotype, but their prevalence is to date limited to sporadic cases.2
See Article by Landstrom et al
Initially, it was suggested that RyR2 mutations causing CPVT cluster in specific residues of the genes; however, reports of CPVT patients harboring mutations outside these clusters prompted the recommendation of screening the entire coding region of the gene.2 Overall, the gene has a negative residual variation intolerance score (a gene-based score that ranks genes from intolerant to tolerant based on whether they have more or less common functional genetic variation),3 hence suggesting that most variants are expected to be deleterious. The Heart Rhythm Society/European Heart Rhythm Association Expert Consensus2 advises the use of genetic testing in everyone with a suspect clinical diagnosis of CPVT, based on the high yield of the test and on the malignancy of the disease that could manifest with sudden cardiac …