DNA repair genes - These help to prevent mutations that can cause cancer. For example, a malfunctioning gene is BRCA1, which is the gene for breast cancer. The celebrity Angelina Jolie has this gene. If you have it, you are very likely to develop cancer, so it is important that you inform your doctor, so you can get regular checkups, if you are not already. Another example is LIG4. This can cause lung and blood cancer.