To investigate whether individuals in the two families develop ACM if they carry the PKP2 mutation and a variant that affects a second unknown gene, a set of putative causal genes was compiled in each family. All genes were determined that have a least one variant that meets the following three criteria: (i) The variant has a consequence, that is classified as either “high” (transcript ablation, splice acceptor variant, splice donor variant, stop gained, frameshift variant, stop lost, start lost, transcript amplification) or “moderate” (inframe insertion, inframe deletion, missense variant, protein altering variant) by Ensembl. (ii) The variant is either present in the family’s affected individuals and not in any family’s PKP2 carrier individuals or it is present in the family’s PKP2 carrier individuals and not in any family’s affected individuals in either a dominant or a recessive mode. (iii) The variant has a coverage of at least 10X in all affected and carrier individuals.