A<unk>  is a<unk>  in either of the<unk> 1 and<unk> 2 genes, which are tumour suppressor genes. Hundreds of different types of<unk> s in these genes have been identified, some of which have been determined to be harmful, while others have no proven impact. Harmful<unk> s in these genes may produce a hereditary breast–ovarian cancer syndrome in affected persons. Only 5–10% of breast cancer cases in women are attributed to<unk> 1 and<unk> s (with<unk> s being slightly more common than<unk> s), but the impact on women with the gene<unk>  is more profound. Women with harmful<unk> s in either<unk> 1 or<unk> 2 have a risk of breast cancer that is about five times the normal risk, and a risk of ovarian cancer that is about ten to thirty times normal. The risk of breast and ovarian cancer is higher for women with a high-risk<unk>  than with a<unk> . Having a high-risk<unk>  does not guarantee that the woman will develop any type of cancer, or imply that any cancer that appears was actually caused by the<unk> , rather than some other factor. High-risk<unk> s, which disable an important error-free DNA repair process (homology directed repair), significantly increase the person's risk of developing breast cancer, ovarian cancer and certain other cancers. Why<unk> 1 and<unk> s lead preferentially to cancers of the breast and ovary is not known, but lack of<unk> 1 function seems to lead to non-functional X-chromosome inactivation. Not all<unk> s are high-risk; some appear to be harmless variations. The cancer risk associated with any given<unk>  varies significantly and depends on the exact type and location of the<unk>  and possibly other individual factors.<unk> s can be inherited from either parent and may be passed on to both sons and daughters. Each child of a genetic carrier, regardless of sex, has a 50% chance of inheriting the mutated gene from the parent who carries the<unk> . As a result, half of the people with<unk>  gene<unk> s are male, who would then pass the<unk>  on to 50% of their offspring, male or female. The risk of<unk> -related breast cancers for men with the<unk>  is higher than for other men, but still low. However,<unk> s can increase the risk of other cancers, such as colon cancer, pancreatic cancer, and prostate cancer. Methods to diagnose the likelihood of a patient with<unk> s in<unk> 1 and<unk> 2 getting cancer were covered by patents owned or controlled by Myriad Genetics. Myriad's business model of exclusively offering the diagnostic test led to Myriad growing from being a startup in 1994 to being a publicly traded company with 1200 employees and about $500M in annual revenue in 2012; it also led to controversy over high prices and the inability to get second opinions from other diagnostic labs, which in turn led to the landmark Association for Molecular Pathology v. Myriad Genetics lawsuit.
BRCA mutation
History of radiation therapy
Chromosomal fragile site
Radiation exposure
Human papillomavirus infection
SAMPLE history
Dichromacy
ALPSA lesion