SUN-721 Implementation of Whole Exome Sequencing for Clinical Diagnostics: A Prospective Busan Kyung-Sang Regional Co-Work Team Experience

Purpose: Next Generation Sequencing (NGS) technology is a highthroughput method for genome sequencing which assists clinicians with diagnosis of patients with suspected genetic disorders. This study was to investigate diagnostic yield and clinical utility of whole exome sequencing prospectively in the rare genetic diseases. Method: WES was performed a total of 178 patients with suspected genetic disorder. Buccal swab samples were collected from the patients to extract genomic DNA. WES and variant interpretation was conducted in 3 Billion Inc (Seoul, Republic of Korea), based on their own software. Patients’ phenotype was interpreted by clinical geneticists. Results: WES reported 117 variants (66.7%). According to the ACMG/AMP guidelines, there were 25 pathogenic variants (14%), 37 likely pathogenic variants (32%), and 55 VUS (31%). Among the 117 patients who detected variants, genotype-phenotype correlation was analyzed and resulted that 44 (38%) were found to be apparently causal mutation of the disease, 37 (32%) were not considered the cause of the disease, and 36 (31%) were withheld judgement. Of the VUS variants, 13% were likely to be the causal variants of the disease considering phenotype of patients. Conclusion: This study showed 38% of diagnostic yield in patients with unidentified genetic condition by using prospective WES based on automating variant interpretation system. In the diagnosis of rare genetic disease, we identified the need for a multi-disciplinary team to select appropriate subjects and interpret the clinical significance of the found genetic variants.