OBJECTIVETo study on mutations in D-loop region which is gene control region of mitochondrial genome in patients with familial breast cancer.

METHODSTwenty-three breast cancer patients came from twenty-one families of breast cancer, and eighteen healthy controls participated in the study. PCR amplification of D-loop region in mitochondrial DNA was performed and then the product was sequenced to analyze mutations.

RESULTSOne hundred and twenty-six mutations in D-loop region were found in twenty-three patients with familial breast cancer, and four mutations were new. In all of twenty-three patients, thirty-seven mutations were found in D310 which was hot spot of D-loop region in mitochondrial DNA. In these mutations, T>C in 310, TC insert in 311-312, CA deletion in 522-523 and C>G in 527 were multi-presentation mutations in patients with familial breast cancer. Mutations had no difference in the same family member of breast cancer family except that occurrence in the region of D310. In the same family, mutations in D310 of patients were different from controls.

CONCLUSIONMutations in D310 of familial breast cancer patients may enhance their susceptibility to breast cancer.