RE: Scientific American (Mar 07) New Predictors of Disease

[Guest guest]

The short answer about genetic testing is yes, eventually.

The longer answer is no, not at present.

The reason is that genetic testing is relatively meaningless if there's no

reference database. That only exists for a specific number of devastating

and to some extent preventable diseases (e.g. BRCA1 gene mutations in breast

and ovarian cancer). There are several areas of significant current

research; I'm only familiar with a few of them, mostly with respect to

various endocrine diseases. Subtle changes in hormone receptor structure

(polymorphisms) can change the way a person responds to a particular hormone

(either more or less than what is normal for the population). There are

also variations in hormone synthetic pathways that can change hormone

structure or the relative amounts of hormones, making the lives of those

with these normal variations interesting, to say the least.

The only sort of genetic testing that can currently yield any significant

information is to determine one's HLA antigen profile. Much work has been

done on this because HLA antigens have been known for perhaps 40 years, but

since most diseases depend on a complex interplay of heredity and

environment, the best it can do is to yield vague probabilities. There are

some strong associations such as HLA B27 in ankylosing spondylitis; HLA B8

in certain autoimmune endocrinopathies; HLA B4 in some rheumatologic

diseases; and HLA Cw6 in psoriasis and psoriatic arthritis. Some have also

been found to protect from the worst forms of autoimmune disease,

specifically HLA DR7. I actually got myself HLA-typed shortly after I got

sick (this was in the early '90s), and found that I was not at significant

risk for ANY autoimmune disease (backed by my negative family history).

There are probably enough of us who are self-identified as having gotten

sick from The Shot to form a viable database. We would have to find the

money to subsidize a thorough look at our individual genomes in order to

discover any commonalities we have. I personally believe that all the

impurities in The Shot yielded enough different antigens to put many of us

at risk. I also believe that the composition of The Shot varied so much

between lots that we each need to know the lots we received (and the lots

themselves analyzed) in order for any testing to be meaningful.

With respect to Parkinson's, I can't add anything to Meryl's reply, and what

I mentioned earlier. Parkinson's seems to be degenerative in nature rather

than autoimmune, but in medicine one learns that " always " or " never " don't

apply; " probable " and " improbable " do.

===========================================================================

''Is it going to mean you can remember where you left your

car keys? We can't say that.''

-- DR. ELIZABETH EDGERLY,

a psychologist with the Alzheimer's

Association, on programs that promote

brain health. (NYT 27-Dec-06)

===========================================================================

..>

..>