A hereditary predisposition to breast cancer significantly influences screening and follow-up recommendations for high-risk women. Prediction models suggest that there are unlikely to be additional yet to be identified high-penetrance genes. Investigation of common, low-penetrance alleles contributing to risk in a polygenic fashion has yielded a small number of suggestive single-nucleotide polymorphisms SNPs , but the contributive risk of an individual SNP is quite small. Mutation testing is currently recommended for individual genes in the appropriate clinical setting where there is a high index of suspicion for a specific mutated gene or syndrome. Next-generation sequencing offers a new venue for risk assessment. At the present time, there are clear clinical guidelines for individuals with a mutation in a high-penetrance gene.
Myriad Genetics - Wikipedia
Breast cancer is the second most common cancer in women after skin cancer. Each year, approximately , women in the United States are diagnosed with breast cancer, and one in nine American women will develop breast cancer in her lifetime. Breast cancer is a common disease. But hereditary breast cancer - caused by a mutant gene passed from parents to their children - is rare. Estimates of the incidence of hereditary breast cancer range from between 5 to 10 percent to as many as 27 percent of all breast cancers. A year later, a second gene associated with breast cancer - BRCA2 - was discovered on chromosome
Breast cancer is a disease in which certain cells in the breast become abnormal and multiply uncontrollably to form a tumor. Although breast cancer is much more common in women, this form of cancer can also develop in men. In both women and men, the most common form of breast cancer begins in cells lining the milk ducts ductal cancer.
Germline mutations in BRCA1 and BRCA2 confer high risks of breast and ovarian cancer, but the average magnitude of these risks is uncertain and may depend on the context. Breast and ovarian cancer incidence rates for mutation carriers were estimated using a modified segregation analysis, based on the occurrence of these cancers in the relatives of mutation-carrying index case patients. We found some evidence for a reduction in risk in women from earlier birth cohorts and for variation in risk by mutation position for both genes.