CHEK2 and cancer: In addition to BRCA1 and BRCA2, germline mutations in five additional susceptibility genes, including tumour protein P53 (TP53), phosphatase and tensin homologue (PTEN), checkpoint kinase 2 (CHEK2), ataxia telangiectasia mutated (ATM), and partner and localizer of BRCA2 (PALB2), have been recognized as cancer‐related genes in breast cancer patients.41, 42, 43, 44