Complex sentence: Mutations within the desmosome are the main cause of Arrhythmogenic right ventricular cardiomyopathy (ARVC), a life-threatening disease caused by mutations usually in Desmoglein 2, but sometimes in Desmocollin 2.
Split into simpler sentences: Mutations within the desmosome are the main cause of Arrhythmogenic right ventricular cardiomyopathy (ARVC). It is a life-threatening disease caused by mutations most commonly in Desmoglein 2, but sometimes is seen in Desmocollin 2.