A Single Center Prospective Study in an Estimated 570 Patients Who Underwent Genetic Screening at UZ Brussel in the Context of a Primary Cardiac Arrhythmia. Patients Showing a Variant Class 3,4 or 5 in SCN4A or CLCN1 Will Undergo a Clinical and Electrophysiological Review After IC.

A prospective interventional single-center study will be conducted. The study includes clinically diagnosed Intramuros PCA-patients who underwent a PCA gene panel of 113 genes (see Appendix 1) in the UZ-Brussel since 2021. In a retrospective part of the study, we will assess cardiac history, cardiac family history, cardiac exams and medical treatment and genetic data and family history. The prevalence of a class 3, 4 or 5 variant in the SCN4A and CLCN1 gene in the PCA-group will be compared to controls who underwent genetic screening for different causes, in which no association with muscular channelopathies is expected, without access to their medical file. In a prospective part of the study, patients with PCA carrying a variant class 3,4 or 5 in the SCN4A gene or a variant class 3, 4 or 5 in the CLCN1 gene will be invited for a one day visit for an interview, clinical neurological assessment and EMG. The aim of this second phase is to describe the clinical presentation of patients with concomitant PCA and non-dystrophic myotonia .