Aberrant expression of interleukin 1 receptor associated kinase 1 (IRAK1), serpin family I member 2 (SERPINI2), and WW and C2 domain containing 1 (WWC1) was reported to be associated with breast cancer metastasis [67,68,69], although the relationship between their mutation status and brain metastasis remains to be elucidated. The gene discussed is WWC1; the disease is metastasis.