The risk of developing HER2 positive BC was increased 37.5 times in individuals with MSH6 pathogenic variants compared with variants in other genes (p = 0.031) and the risk of developing luminal A BC was reduced by 77% (p = 0.089) in patients with BRCA1 pathogenic variants and this was maintained when adjusting by age. This evidence concerns the gene BRCA1 and breast cancer.