CHEK2 and breast cancer: Among the HER2+ group, only TP53 (OR: 23.8, 95% CI: 6.5–86.6) was classified as a high risk breast cancer susceptibility gene, while BRCA2 (OR: 4.5, 95% CI: 2.8–7.2); BRCA1 (OR: 3.4, 95% CI: 1.7–6.8); PALB2 (OR: 3.2, 95% CI: 1.4–7.3); and CHEK2 (OR: 3.8, 95% CI: 1.7–8.5) were classified as moderate risk breast cancer susceptibility genes (Table 3).