Exome sequencing of the index individual in each family and variant filtering were performed as previously described.7 In brief, WES was performed with the TruSeq Exome Enrichment Kit from Illumina. Coding and splicing homozygous variants were considered as candidates only if they were present within the candidate locus, had a frequency < 0.1% in publicly available variant databases (1000 Genomes, NHLBI Exome Sequencing Project Exome Variant Server, and Genome Aggregation Database [gnomAD]) and a database of in-house ethnically matched exomes (Saudi Human Genome Program; totaling 2,379 exomes), and were predicted to be pathogenic in silico.