Most cases in our cohort (northern Chinese population) are sporadic BC, and the top 3 frequent mutated genes in were MUTYH (5/17, 22.2%), BARD1 (14/90, 15.6%) and BRCA2 (38/253, 15.0%), and the frequency of top 2 P/LP variants are MUTYH (5/187, 2.26%) and RAD51D (2/90, 2.22%). Here, BARD1 is linked to breast cancer.