b>Summary: The rapid progress in studies of genes involved in inherited susceptibility to breast and or ovarian cancer is reported. Approximately 5-10% of breast cancers are believed to arise from the inheritance of genes that confer an elevated risk for the disease. In such cases, breast cancer usually presents at an early age and tends to cluster in families along with other cancer types, notably ovarian cancer. Two genes associated with susceptibility to breast cancer, known as BRCA 1 and BRCA 2, are localized on chromosomes I7q21 and 13q12—13, respectively. The complete nucleotide sequence of BRCA 1 has been published and about 100 distinct mutations in families with hereditary breast and ovarian cancer were found so far. Mutations in the final third of the BRCA 1 gene are usually sufficientto cause breast cancer. In families afflicted by both types of tumour, the mutations occur nearerto the beginning of the BRCA 1 gene. Mutations in the BRCA 2 gene are associated with high penetrance of breast cancer but with a lower risk of ovarian cancer. Other genes that confer increased risks of breast or ovarian cancer in addition to other cancers are also described.
Genetic mutation leading to heritable forms of breast and ovarian cancer
