Sharp et al. [96] found that the cytochrome c oxidase, subunit 2 (CO2) is expressed at significantly higher levels in carcinomas as compared to fibroadenomas, while no differences were found for ATPases or ND2 and ND4. The only author [75] who considered mitochondrial PCGs alterations in familial compared to sporadic breast cancer patients showed a significant increased frequency of variations in 16S rRNA, ATP6, ND3 and ND5; while the synonymous G11719A alteration in ND4 gene has been significantly associated to familial breast cancer by our studies still unpublished (Fig. 1). Here, MT-ND4 is linked to breast cancer.