Importance of Diagnosis in Breast Cancer with Non-BRCA Pathogenic Germline Variants of Cancer Susceptibility Genes using High-Throughput Sequencing Analysis

to out the importance of the diagnosis of breast by the predisposition genes except BRCA1/2 with multigene testing. Methods: In this study, 232 non-BRCA cases with BC and/or BC family history (FH) were analyzed using the next-gen-eration sequencing method. Twenty-two different pathogenic/likely pathogenic variants were determined in 24 (10.34%) of cases, and these variants were detected in the CHEK2 (7/24, 29.1%), ATM (5/24, 20.8%), MUTYH (3/24, 12.5%), BLM (2/24, 8.3%), WRN 8.3%), TP53 (1/24, 4.1%), BRIP1 (1/24, 4.1%), MSH2 (1/24, 4.1%), NBN (1/24, 4.1%), and PTEN (1/24, 4.1%) genes including three novel variants which were identified in the BLM, ATM , and MSH2 (3/22, 13.6%) genes. Fourteen of 24 (58.3%) cases had BC diagnosis, and 10 of 24 (41.6%) cases had a FH of BC. Conclusion: Among non-BRCA BC and/or BC FH cases, cancer susceptibility gene frequency was 10.34% in this study. CHEK2 and ATM genes had relatively high mutation rates. Abstract