TOP3B and breast cancer: Other than BRCA1/2, 10 additional mutations were observed in the genes involved in HDR pathway (NBN, NSMCE1, POLD1, RECQL4, RMI1, RTEL1, SLX4, SMC5, TOP3B, and XRCC3), which may be also responsible for the CMT pathogenesis as shown in the example of NBN germline variants and associates breast cancer risk24.