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Archiver > GENEALOGY-DNA > 2009-09 > 1254013037


From: "Roberta Estes" <>
Subject: Re: [DNA] 23andMe - How Helpful are the Health Traits Really?
Date: Sat, 26 Sep 2009 20:57:17 -0400
References: <E0A4E58EFC3D44D0AB86EAF9CCB47661@RESTES2007><200909270031.n8R0Vs2L022027@mail.rootsweb.com>
In-Reply-To: <200909270031.n8R0Vs2L022027@mail.rootsweb.com>


Tim and Ann,

Thank you both for taking the time to help us all understand this complex
issue. I'm very grateful that we have people with your level of expertise
available and willing to share.

Roberta

-----Original Message-----
From:
[mailto:] On Behalf Of Tim Janzen
Sent: Saturday, September 26, 2009 8:32 PM
To:
Subject: Re: [DNA] 23andMe - How Helpful are the Health Traits Really?

Dear Roberta,
These are good questions and I am not sure I am qualified to answer
them completely accurately since I don't consider myself to be an expert on
BRCA1 or BRCA2. Ann Turner probably has more extensive knowledge about this
than I do and may want to comment on this. From what I have read at
https://www.23andme.com/you/journal/brca/overview, 23andMe tests for two
mutations in BRCA1 and one mutation in BRCA2 that are associated with
increased risk for breast and ovarian cancer. These mutations are the
185delAG BRCA1 mutation, the 5382insC BRCA1 mutation, and the 6174delT BRCA2
mutation. The 23andMe web site also says this: "The absence of these
mutations does not rule out the possibility that a person may carry another
genetic variation that increases the risk of these diseases." As Ann
mentioned in her message this morning, the BRCA1 gene is very large and
there are hundreds and hundreds of known mutations. That said, it appears
that the above 3 mutations that 23andMe tests for account for a significant
percentage of people who have BRCA1 or BRCA2 mutations who develop breast
cancer. However, I don't know the exact percentage. The 185delAG BRCA1
mutation was found in 20% and the 6174delT BRCA2 mutation in 8% of Ashkenazi
Jewish women with early-onset breast cancer per the article at
http://www.nature.com/ng/journal/v14/n2/abs/ng1096-188.html.
An article I found at
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1712523 also
mentioned the 188del11 mutation, which apparently isn't tested for by
23andMe. This article says that 30% of the women of Ashkenazi Jewish
ancestry who were diagnosed with breast cancer before the age of 40 had one
of the above 4 mutations and 10% of the women of Ashkenazi Jewish ancestry
who were diagnosed with breast cancer after the age of 40 had one of the
above 4 mutations.
I also found this article to be of interest:
http://hmg.oxfordjournals.org/cgi/content/full/7/5/801. This article says
that the 185delAG BRCA1 mutation originated before the dispersion of Jews in
the Diaspora and is not limited to Ashkenazim.
These articles are also of interest:
http://jmg.bmj.com/cgi/content/full/42/7/602
http://cat.inist.fr/?aModele=afficheN&cpsidt=1714551
http://jnci.oxfordjournals.org/cgi/content/abstract/90/13/995
http://www.ajph.org/cgi/content/full/96/11/1979
http://www.scielo.cl/scielo.php?pid=S0716-97602002000100011&script=sci_artte
xt

Per the information at
https://www.23andme.com/you/journal/breastcancer/techreport, 23andMe also
tests for at least two SNPs in the FGFR2 gene that are associated with
breast cancer risk: rs1219648 and rs2420946. The genotype AA for rs1219648
is associated with an adjusted odds ratio of .83 for breast cancer. The
genotype GG for rs1219648 is associated with an adjusted odds ratio of 1.35.
23andMe also tests for a SNP in the 16q12 region that is associated with
breast cancer risk: rs3803662. The genotype GG for rs3803662 is associated
with an adjusted odds ratio of .85 for breast cancer. The genotype AA for
rs3803662 is associated with an adjusted odds ratio of 1.4 for breast
cancer.
From what I recall from an article on this topic that I read several
months ago, the tests for BRCA1 and BRCA2 mutations were developed by a
company called Myriad Genetics that has proprietary rights to those tests.
They have patents on at least some of the mutations in their tests.
Apparently those patents will be in effect for 20 years. It is possible
that 23anMe is prohibited from testing all of the BRCA1 and BRCA2 mutations
were discovered by the company that developed the tests since that would be
patent infringement.
This whole topic is somewhat contentious at this time. I read
recently that the ACLU is suing to prevent genetics companies from patenting
any more DNA sequences in humans. See
http://blog.aclu.org/2008/10/02/brca-genetic-testing-and-civil-liberties-its
-what-christina-applegate-oprah-and-pbs-are-all-talking-about
for some additional information about this. Once whole genome testing
becomes widely available and affordable there will be a lot of people who
will want to figure out whether they have mutations in BRCA1 or BRCA2 that
place them at higher risk for breast cancer as well as a lot of other
genetics tests that are currently patented. They will want to look at their
own genome to find these mutations without having to pay the genetics
company that patented the gene. I understand both sides of this issue. On
one hand it is admirable that genetics companies invested a lot of time and
money to find the links between many genetic diseases and specific mutations
in the genome. On the other hand, consumers will want to learn the maximum
amount of genetic risk information from their genomes that they can without
having to pay genetics companies a lot of money for the tests that the
genetics companies developed.

Sincerely,
Tim Janzen

-----Original Message-----
From:
[mailto:] On Behalf Of Roberta Estes
Sent: Saturday, September 26, 2009 3:31 PM
To:
Subject: Re: [DNA] 23andMe - How Helpful are the Health Traits Really?


Tim, are there cases where the BRCA1 predisposition would not show up on the
23andMe test but the person would still have the BRCA1 predisposition,
assuming it's not a "family mutation"? In other words, does a "negative" on
this test mean they are "in the clear" for that kind of breast cancer?

Roberta



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