Final answer:
The BRCA1 and BRCA2 genes are important for DNA repair, with mutations leading to a greater risk of cancer. They are linked genes on autosomes. Genetic markers like d13s 1699 and d13s 1701 near the BRCA2 gene require further research to confirm any linkage to cancer.
Step-by-step explanation:
The BRCA1 and BRCA2 genes are crucial for DNA repair, particularly in homologous recombination repair of double-stranded DNA breaks. When these genes are mutated , they lose their ability to correctly repair DNA, leading to a higher risk of developing breast and ovarian cancers. BRCA1 and BRCA2 are indeed considered linked genes because they tend to be inherited together, and they are located on autosomes (chromosome 17 for BRCA1 and chromosome 13 for BRCA2) rather than sex chromosomes.
The presence of genetic markers such as d13s 1699 and d13s 1701 proximal to the BRCA2 gene suggests that they might be linked to an increased risk of cancer, especially if they demonstrate strong linkage disequilibrium with known BRCA2 mutations. However, genetic linkage does not confirm causation, and further study would be required to establish whether these particular markers are associated with the disease.
Genetic mutations in BRCA1 and BRCA2 can be more prevalent in certain ethnic groups due to historical population sizes and genetic drift. For example, mutations in these genes are particularly common among Ashkenazi Jews. Furthermore, not all individuals with these genetic mutations will develop cancer; they simply have a higher risk compared to the general population.