colorisnteverything wrote:
I am with Lisa. BMX, oncologists have suspected (due to studies and clinical observations) that this is a trait that is passed down on the mother's side. And while it is 50% likelihood that you have the gene, the gene does NOT mean that you will automatically develop cancer. Go to the bracanalysis.com site and see the actual statistics on their trials. I only know because my cousin A has had breast cancer 3 times now, except for it has now spread. All of her children have been tested. She will probably die in the next year or so if the experimental trial she is on now does not work.
The risk of inheriting the GENE (if one parent carries one copy on a non-sex chromosome) CANNOT be more than 50%.
The risk of developing the TRAIT (cancer) *IF* you inherit the gene varies widely, due to other genes AND due to sex.

This is NOT the same as "passed down on the mother's side." That's "inheritance."
"Inheritance" is different from "penetrance" or "expressivity."
The trait (development of cancer due to a BRCA mutation) is more PENETRANT in women. As in, women with BRCA mutations get cancer more often than men do (due to the presence of susceptible tissues and sex hormones).
That's why it's identified more often/ easier to see in female parts of the pedigree. There is also testing bias - women with female relatives who develop reproductive cancers are MORE LIKELY to be tested.
Penetrance, however, has NOTHING to do with inheritance.

This is directly from the site you linked.
"BRCA1 and BRCA2 mutations causing HBOC are passed on in families in an autosomal dominant pattern—meaning that someone with this mutation has a 50% chance of passing it on to each of his or her children. Knowing the mutation came from the mother or father is helpful, because other family members on that side of the family (aunts, uncles, cousins, etc.) may also carry the mutation."
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Btw, I couldn't find any statistics on that site that would be relevant here? But I always check my facts in the medical lit before I post medical information. I can't find anything that supports the assertions about inheritance. But I did find this in JAMA:
"Although experienced geneticists and cancer risk counselors know to assess more-distant relatives (third- and fourth-degree) for potential clues to support a recommendation for BRCA gene testing, busy oncology or primary care clinicians rarely have the time to obtain and qualify a pedigree beyond 1 or 2 generations. In addition, a recent survey study found that less than one quarter of health care professionals and medical students knew the importance of paternal family history in evaluation of hereditary breast cancer, highlighting the need for continuing professional education.33"
(
Limited Family Structure and BRCA Gene Mutation Status in Single Cases of Breast Cancer, Jeffrey N. Weitzel, MD; Veronica I. Lagos, MS; Carey A. Cullinane, MD; Patricia J. Gambol, MS; Julie O. Culver, MS; Kathleen R. Blazer, MS; Melanie R. Palomares, MD; Katrina J. Lowstuter, MS; Deborah J. MacDonald, PhD, JAMA 2007;297:2587-2595.)