Frequency and spectrum of actionable pathogenic secondary findings in 196 Korean exomes

Purpose: One of the biggest challenges of exome and genome sequencing in the era of genomic medicine is the identification and reporting of secondary findings. In this study we investigated the frequency and spectrum of actionable pathogenic secondary findings in Korean exomes. Methods: Data from 196 Korean exomes were screened for variants from a list of 56 genes recommended by the American College of Medical Genetics and Genomics (ACMG) for return of secondary findings. Identified variants were classified according to the evidence- based guidelines reached by a joint consensus of the ACMG and the Association for Molecular Pathology. Results: Among the 196 exomes, which were from 100 healthy controls and 96 patients with suspected genetic disorders, 11 variants in 13 individuals were found to be pathogenic or likely pathogenic. We estimated that the frequency of actionable pathogenic secondary findings was 7% for the control subjects (7/100) and 6% for the patients with disease (6/96). For one autosomalrecessive disease, four individuals exhibited either one pathogenic or one likely pathogenic variant of the MUTYH gene, leading to a carrier frequency of 2% (4/196). Conclusion: Secondary findings are not uncommon in Korean exomes.