In both pathogenic BRCA1 mutant cancer cells and BRCA1 siRNA depleted cancer cells, Arlt and colleagues showed that two CFSs, FRA3B and FRA16D, manifested elevated expression of the fragility compared to wild-type BRCA1 complemented or control siRNA transfected cells (Arlt et al., 2004). The gene discussed is BRCA1; the disease is cancer.