We found that a majority of complex I members showed differential expression in breast cancer patients, with NDUFAF3, NDUFAF8, NDUFS2, NDUFS3, NDUFS5, NDUFS6, NDUFS7 and NDUFAS8, and NDUFS8 being upregulated in breast cancer tissue, while NDUFAF4, MT-ND1 MT-ND2, MT-ND3, MT-ND4, MT-ND5, MT-ND6, and NDUFS4 were downregulated. The gene discussed is MT-ND4; the disease is breast carcinoma.