BRCA1 and breast cancer: For example, women under the age of 20 with a BRCA1 mutation are very unlikely to get breast cancer; moreover, \documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$28\%$$\end{document}28% of all women with BRCA1 mutation never get the cancer [11].