Known susceptibility genes account for less than 25% of the familial risk of breast cancer, and the residual genetic ariance is likely to be due to ariants conferring more moderate risks.

• 目前已知的易感基因占了不到25%25的乳腺癌家族发病风险基因。余下的基因变异很可能来自于可致中度罹病风险的变异体。