In addition to the Fam1 and Fam2 family members, an unrelated female ACM affected individual, her carrier sister, and their carrier aunt, all carrying a heterozygous PKP2 exon 4 deletion, were used to exclude variants as described in (ii) (see Additional file 1 for details). Variants were not filtered based on allele frequency or pathogenicity prediction. Furthermore, all genes were determined that harbored copy number variations (CNV; either a deletion or a duplication) in the affected and carrier individuals applying the same genotype selection criteria as for variants.