Final answer:
The genetic markers D17S855 and D17S1323 within the BRCA1 gene are linked to hereditary breast cancer. Mutations in BRCA1 and BRCA2 increase cancer risk, and BRCA1/2 mutations are more common among Ashkenazi Jews. These genes are not genetically linked as they reside on separate chromosomes and are involved in DNA repair mechanisms.
Step-by-step explanation:
The markers D17S855 and D17S1323 that are intragenic to the BRCA1 gene have been linked to hereditary breast cancer within some families. These genetic markers have been identified through genetic linkage studies aimed at mapping the location of genes that contribute to diseases, including breast and ovarian cancers, by following the inheritance of traits across generations. BRCA1 and BRCA2 are tumour-suppressor genes, and their mutations are associated with an increased risk of these cancers.
Women with family histories of breast or ovarian cancer can be screened for mutations in these genes. A positive test for a harmful mutation in either gene indicates an increased cancer risk. Mutations in BRCA1 and BRCA2 are relatively more common among individuals of Ashkenazi Jewish descent, with about 1 in 40 having one of these mutations, compounding the importance of genetic testing in individuals from such backgrounds.
BRCA1 and BRCA2 genes are located on chromosome 17 and 13, respectively, and are not linked in the genetic sense as they are on different chromosomes. They are located on autosomes, not sex chromosomes. Their normal function involves participating in the repair of double-stranded DNA breaks, specifically through homologous recombination repair by interaction with other proteins, such as Rad51.