A targeted next-generation gene panel reveals a novel heterozygous nonsense variant in the TP63 gene in patients with arrhythmogenic cardiomyopathy

Background: Arrhythmogenic cardiomyopathy (ACM) is associated with arrhythmias and risk of sudden death. Mutations in genes encoding proteins of cardiac intercalated discs account for ∼60% of ACM cases, but the remaining 40% is still genetically elusive. Objective: The purpose of this study was to identify the underlying genetic cause in probands with ACM. Methods: DNA samples from 40 probands with ACM, negative for mutations in the 3 major ACM genes—DSP, PKP2, and DSG2, were screened by using a targeted gene panel consisting of 15 known ACM genes and 53 candidate genes. Results: About half of patients were found to carry rare variant(s) predicted to be damaging; specifically, 9 (22.5%) showed ≥1 variants in genes associated with ACM and/or with other inherited heart diseases and 10 (25%) showed variants in candidate genes. Among the latter, we focused on 2 novel variants in TP63 and PPP1R13L candidate genes (c.796C>T, p.(R266*) and c.1858G>C, p.(A620P), respectively). The encoded proteins p63 and inhibitor of apoptosis stimulating p53 protein are known to be interacting partners. Inhibitor of apoptosis stimulating p53 protein is a shuttling multifunctional protein: in the nucleus it is critical for inhibiting p63 function, whereas in the cytoplasm it regulates desmosome integrity. According to the American College of Medical Genetics and Genomics guidelines, the variant in TP63 has been scored as likely pathogenic and the variant in PPP1R13L as a variant of uncertain significance. Importantly, the mutant TP63 allele leads to nonsense-mediated messenger RNA decay, causing haploinsufficiency. Conclusion: Our findings identify TP63 as a putative novel disease gene for ACM, while the possible involvement of PPP1R13L remains to be determined.