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gfb1

Member Since 09 Feb 2009
Offline Last Active Nov 17 2010 10:51 AM
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Topics I've Started

Be Careful Out There...

15 July 2009 - 03:54 AM

sometimes humor can help make a point....



:)

Finding The 'real' Gene For Celiac

08 July 2009 - 05:35 AM

another short day for posts... however, this one might actually be important...

23andMe -- one of the new 'personal' genomics companies -- is beginning to build a large-scale database of major human diseases for research. they are trying to incorporate a 'social network'-flavor to identifying important genetic diseases (obviously, one's where they can make $$$) and are (in their words) 'democratizing' that process.

given the vast number of celiacs out there; this might be an opportunity to steer a bit of research our way.
i've already written a brief email to their board noting the expected frequencies of celiac disease in the US (and the potential profits ....), the differing expectations based on race and geography and, most importantly, the inadequacy of the current MHC-haplotype testing. based on large scale interest and the probability of a small number of genes with large effect that are involved in the disease -- i also suggested that they should be able to reduce the current cost ($99) of participation dramatically.

as they say in chicago, "vote early. vote often."

https://www.23andme....archrevolution/

at bare minimum for $99 you can find out your HLA-DQ2.5 type.

Traditionally, HLA-DQ proteins have been detected using blood tests that look at proteins, not genes . (emphasis mine, gfb) These tests can pick up all subtypes of HLA-DQ proteins associated with Celiac Disease. 23andMe is not able to provide data about all subtypes of HLA-DQ2 and HLA-DQ8. We only report data on one subtype of HLA-DQ2. Of all the risky HLA-DQ subtypes, this subtype, called HLA-DQ2.5, is most often associated with Celiac Disease.

further, they have been able to identify 3 fairly large 'blocks' of chromosomes that may contain the non-HLA genes that influence celiac. with more patient participation, they may be able to 'narrow' those blocks to identify the actual genes involved...

Test Results 101: Understanding Normal

02 July 2009 - 05:22 AM

Everybody gets their blood test results back in a haze of unreadable numbers and words. For all the cost, you'd think that the labs would invest in some decent printers, a legible font and maybe even a decently designed graphic (or two) -- [more on this to follow]. There is no reason that any person who can successfully navigate a newspaper or website should have trouble reading the results of a blood test panel.

To begin: what the hell is 'normal'??

as a good friend always reminds me:
there is no such thing as normal – just less extreme outliers.
'outliers' can occur in either direction – high or low – and, while seemingly obvious, changes the mathematical rationale underlying the interpretation of the tests.

'Normal' refers to a variety of things. To most of us, 'normal' means that we are 'not sick'. However, to the laboratory, 'normal' can refer to either the average reference value of a test; OR, the statistical distribution of all test results. For the statistically minded, in MOST cases 'normal' refers to any test value that falls within two (2) standard deviations from the average of all test values. Among friends, this means that IF your test value is within the quoted 'normal' range – your test result is among the 95% of all the results obtained by that laboratory. And yes, to make things complicated, every lab has a different distribution or range, which may also change by day, week, month and year.

Why?
In part, because things change.
The temperature in the lab changes from day to day and season to season, affecting reaction rates and test results. People change jobs, and different technicians often have different distributions (this has changed a bit since the increase in automation and robotics in the laboratory). Reagents used in the tests change from lot to lot; ranging from the concentration of anti-clotting agent in the blood collection tubes, to activity of enzymes, lot of antibodies used in the test, to the age of the light bulbs in the machines that read the tests. There are hundreds, if not thousands, of events that influence the exact value of any test results.

Does this mean that you can't trust the results??

absolutely NOT.
Test results are very reliable (at least 95% of the time!!), as long as you understand the constraints of the test. But the tests are certainly much better at determining whether a test result is within that 95% confidence interval of 'normalcy' than for determining if the individual test result is actually an outlier!!

this had become a much longer post than I had intended... so, I think i'll continue the thread in parts (if anyone finds it useful)....

The Value Of 'gene'/'genetic' Testing

16 April 2009 - 02:35 AM

See
http://www.nytimes.c...rch/16gene.html

“With only a few exceptions, what the genomics companies are doing right now is recreational genomics,” Dr. Goldstein said in an interview. “The information has little or in many cases no clinical relevance.” -- D. Goldstein

david is a VERY good geneticist.

Onset Of Celiac Disease

03 April 2009 - 10:07 AM

i've noticed an increase in the frequency of postings regarding understanding of partially-positive or negative test results, in the face of celiac-like symptoms. conflicting test results also seem to be common.

celiac disease can be considered to be a 'threshold' disease. that is, blood test results and small bowel injury do not occur in a persons life until AFTER some 'threshold' or minimum level of gluten exposure. this threshold level appears to be extremely variable, taking into account both the degree to which one's gastrointestinal tract can metabollize gluten, one's level of inherent immune response to gliadin/gluten as it contacts the intestinal mucosa (probably the role of HLA alleles), the extent of one's immune response AFTER small bowel injury (i.e., following the entry of gliadin into the bloodstream) and, unsurprisingly, the amount of gluten one eats!!

a personal example;
my wife came from a 'meat and potatoes' family -- eating bread approx once per week-- with no health issues.
she had the misfortune of marrying some good looking italian 'guy', who (not to be stereotypical, but.... ) insisited on pasta twice a week and bread at every meal. worse, this poor fellow was a ny/nj-italian-american -- who introduced her to the wide, wonderful (but gliadically evil) world of bagels -- probably 5 times per week (the other 2 breakfasts were usually red bean cakes from chinatown...).
within 2 years, age 23, her health issues started and it took nearly 10 years to be diagnosed.

not a strange story, in and of itself... but, her dad -- who continued on the same meat/potatoes diet -- was only diagnosed with celiac disease 5 yrs ago at the unripe, young age of 77.

so, as equivocal test results start rolling in; remember that in order to consistently test 'postive' across all blood/biopsy tests; you really need to be eating gluten and have 'mature' celiac disease. perhaps contrary to expectations, some of the gastrointestinal outcomes of celiac disease, eg. bloating, gas, diarrhea, occur BEFORE all the clinical testing is postive.

this is probably why the 'old timers' in the group always tell the newcomers to try a gluten free diet for a few weeks to see if you feel better.
the difficulty with this approach involves the personal decision as to whether to re-introduce gluten into the diet in order to test positive...