The study involved living relatives of 277 women with genetic faults in the BRCA1 or BRCA2 genes, the majority of whom had breast or ovarian cancer.
Almost half of the 531 relatives tested negative for genetic faults, but 28 of the women went on to develop breast cancer.
Among the 184 first-degree relatives who tested negative for BRCA1 or BRCA2 gene faults, one in four had appeared to have gene modifiers that mimicked the physiological changes associated with the known gene fault.
rachel.liddle@haymarket.com