One gene, peroxisome proliferator- activated receptor-γ coactivator-1 α (PPARGC1A), was a candidate gene in two families and was the only breast cancer susceptibility candidate gene that we could demonstrate by semi-quantitative real-time RT-PCR as being consistently upregulated after GINI in affected members of the family, but not in most unaffected relatives. This evidence concerns the gene PPARGC1A and breast cancer.