BRCA 1 gene is located on:
• Tumor-suppressor gene, BRCA-1, has been identified at the chromosomal locus 17q21.;this gene encodes a zinc finger protein and the product therefore may function as a transcription factor. The gene appeals to be involved in gene repair. Women who inherit a mutated allele of this gene from either parent have at least a 60-80% lifetime chance of developing breast cancer and about a 33% chance of developing ovarian cancer. The risk is higher among women
born after 1940, presumably due to promotional effects of hormonal factors. Men who carry a-mutant allele of the gene have an increased incidence of prostate cancer and breast cancer.
• BRCA-2, which has been localized to chromosome 13q12, is also associated with an increased incidence of breast cancer in men and women.