This work expands upon our previous splicing analyses of the breast cancer susceptibility genes RAD51C, RAD51D, PALB2, ATM, and CHEK2, conducted within the Breast Cancer After Diagnostic Gene Sequencing (BRIDGES) project (https://cordis.europa.eu/project/id/634935, accessed on 12 May 2025), where 34 known or suspected BC susceptibility genes were sequenced in 60,466 BC cases and 53,461 controls [10]. This evidence concerns the gene ATM and breast cancer.