In order to uncover the mechanisms underlying BC recurrence mediated by these mutations, we first analyzed the mRNA expression levels of MLL, EP400 and PRDM2 by real time PCR (RT-PCR) between the non-mutated primary group and the mutated recurrent group (n=20 for primary tumors, n=4 for recurring tumors). The gene discussed is KMT2A; the disease is breast cancer.