PTPN22 and breast cancer: For example, The Cancer Genome Atlas (TCGA) (182) identified 35 significantly mutated genes in breast cancer from analysis of 507 tumour genomes, including 10 novel genes TBX3, RUNX1, CBFB, AFF2, PIK3R1, PTPN22, PTPRD, NF1, SF3B1 and CCND3. This cohort included genomes harbouring deleterious germline variants in breast cancer susceptibility genes involved in DDR (ATM, BRCA1, BRCA2, CHEK2, PTEN and TP53) (Table 1).