a parent. (Gene Clinics, 2000). The parent may or may not have had a cancer diagnosis depending upon the penetrance of the mutation, the gender of the parent, the age of the parent with mutation and other variables. It is appropriate to offer mutation analysis to both parents of an individual with a BRCA1 or BRCA2 cancer predisposing mutation. (Gene Clinics, 2000).In inherited forms of cancer, the parent passes on the gene mutations through a loss of either the maternal or paternal allele within the egg or sperm from which an individual is conceived. Thus every child that is conceived thereafter has a possibility of passing it on to his or her child. (Transmed Network-Breast Cancer-Characteristics of Hereditary Breast Cancer, 1997). The off spring of an individual identified as having either the BRCA1 or BRCA2 mutations have a fifty percent chance of inheriting the mutation themselves. (Gene Clinics, 2000). If the mutation exists in someones genetic makeup it is considered a dominant trait and can be passed down generation to generation as long as it remains dominant. The mutation may also be passed down as a recessive gene in the genetic makeup. The risk that a sibling will inherit the cancer predisposing BRCA1 and BRCA2 mutation is fifty percent if at least one parent had the BRCA1 or BRCA2 cancer predisposing mutation as well. If one sibling inherited the mutation it does not mean that the other siblings will also inherit the mutation. However, the risk of developing the cancer depends upon the kind of mutation, the gender of the individual, and the persons age. (Gene Clinics, 2000) Studies showed that the BRCA1 cancer predisposing gene is linked to forty five percent of site specific related breast cancer and thirty five percent of site specific cases were related to the BRCA2 gene. (Transmed Network-Breast Cancer, 1997). A person who has the modified gene, labeled BRCA1, has an eighty five percent lifetime risk for...
