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Breast cancer is the most commonly diagnosed cancer in women. Despite recent advances in breast cancer research, a comprehensive set of genetic markers of increased breast cancer risk remain elusive. Recently mitochondrial DNA (mtDNA) mutations have been found in many types of cancer, including breast cancer. To investigate the possible role of mitochondrial genetics in breast cancer predisposition and biology we analyzed the D-loop sequence of cancer patients and assigned mitochondrial haplogroup using RFLP analysis. We detected a significantly greater incidence of mtDNA polymorphisms T239C, A263G and C16207T and a significant lower incidence of A73G, C150T, T16183C, T16189C, C16223T, T16362C in patients with breast cancer compared to database controls. The mitochondrial haplogroup distribution in patients with breast cancer differs from a group of cancer-free controls and the general Polish population in that haplogroup I is over-represented in individuals with cancer. These findings suggest that mitochondrial haplogroup I as well as other polymorphic variants defined by SNPs in the D-loop may be associated with an increased risk of developing breast cancer.

Breast cancer is the most frequently diagnosed female cancer all over the world. Although the molecular genetics of this disease has been the focus of many projects for over 20 years, the number of prognostic markers used in clinics is still unsatisfactory. Mitochondrial DNA mutations have been reported in many breast cancer studies. To investigate the possible role of mitochondrial inherited polymorphisms in breast cancer development we analyzed the sequence of NADH-dehydrogenase genes in cancer samples and their corresponding normal tissues. We detected increased incidence of mtDNA polymorphisms, in particular very rare polymorphisms such as A4727G, G9947A, A10044G, A10283G, T11233C, and C11503T. Our report supports the notion that mtDNA polymorphisms establish a specific genetic background for breast cancer development and that mtDNA analysis may help in selection of cohorts that should undergo intensive screening and early detection programs.

Mitochondria have been implicated in cell transformation since Otto Warburg considered 'respiration damage' to be a pivotal feature of cancer cells. Numerous somatic mitochondrial DNA (mtDNA) mutations have been found in various types of neoplasms, including breast cancer. Establishing the mtDNA mutation pattern in breast cancer cells may enhance the specificity of cancer diagnostics, detection and prediction of cancer growth rate and/or patients' outcomes; and therefore be used as a new molecular cancer bio-marker. The aim of this review is to summarize data on mtDNA mutation involvement in breast cancer and estimate effects of resulting amino acid changes on mitochondrial protein function. In this article published mtDNA mutation analyses are critically evaluated and interpreted in the functional context.