Exome analysis
Segregation analysis was performed on all three phenotypes of interest in the Lebanese family, which may exhibit epistatic interaction in development of cardiomyopathy, heart block and AF. A computer script was designed for variants annotation based on the novelty, conservation, tissue expression and their effect on protein function. They were considered non-conservative if the substituted amino acid was conserved in all species. Filtering criteria included frequency (<1/1000), and splice site location (-2 to +2 intron exon boundary). Synonymous, intronic variants, and variants with low quality were filtered out. Variants that were predicted to be benign by two in silico tools (SIFT, and Polyphen2) as well as by other by other laboratories were filtered out early in the analysis. CADD score was additionally used to predict pathogenicity and variants with a score of less than 10 were excluded. Regions prone to sequencing errors were screened then all the related duplications and deletions were filtered out. Also, all variants in known AF-associated genes were screened for allele frequencies <1% in the Gnomad database. Lastly, intolerance score and phyloP 46-way score were used as a measure of conservation. The GTEx portal was used to filter out genes without cardiac tissue expression.