One heterozygous pathogenic variant (NM_024334.3(TMEM43):c.1073C>T; p.Ser358Leu) was identified as a founder mutation in a large number of patients and families from Newfoundland, Denmark, and Germany and has also been identified in other populations.15,22 It is associated with a highly penetrant and arrhythmogenic subtype of ARVC in which biventricular involvement can often be appreciated. The gene discussed is TMEM43; the disease is Arrhythmogenic right ventricular dysplasia.