Surprise, Surprise, Genetic risks in Diabetes and Melanoma!
Posted Apr 21 2009 11:35pm
The Annals of Internal Medicine has a great article this week on genetic risks so does the ACMG Genetics in Medicine Journal for May.
The take home point is something which people may find interesting and it is something I feel is very real. I have begun to think that these Genomic tests act a lot like a placebo. They often don't add anything clinically. Hell, they may not even do anything to guide therapy (Pgx and high penetrance genes aside)
But they often act psychologically, either for good, or for bad.
First in the Annals of Internal Medicine; People have been arguing that perhaps testing only ONE snp andrepresenting its risk is for disease is sillyand in fact taht the REAL way to represent these risks is with a multiSNP panel. In Fact, this is what has been perhaps the selling point of some DTC genomics companies.
Even with this possibilty, the CDC and NIH are not satisfied with what the DTC companies are representing as risk.......Psychologically, that could be devastating to the would be consumer. Lack of public trust is a BIG DEAL......even in this era of lack of trust in everyone.
So let's look at what a multiSNP panel would do. The deCode/DNADirect T2 test looks at TCF7L2 (rs12255372), CDKAL1(rs7756992), PPARG( rs1801282),, CDKN2A(rs564398)
The Annals did a scientific study looking at these SNPs as well as loci including HHEX (rs1111875), IGF2BP2 (rs4402960), SLC30A8 (rs13266634), WFS1 (rs10010131), CDKN2A/B (rs564398, rs10811661) and KCNJ11 (rs5219).
What did they find?
The GRS significantly improved case–control discrimination beyond that afforded by conventional risk factors, but the magnitude of this improvement was marginal: Addition of the GRS increased the AUC by only 1%. This is why I love science. The Journalists and Public read the word SIGNIFICANTLY different than I. In this case, statistical significance (which this word connotes) is essentially a useless guidepost. Becaue the enhanced effect was ONLY 1% better rates of prediction.....But my guess is that a crafty PR propaganda firm would USE the word Significantly in a far different way to manipulate the public.
Hence, placebo effect by hyped study results. The result? Buying more tests? Ask DeCode or DNADirect about that one.
But in this case if the results caused a patient to lose weight and exercise, that would be great. I am STILL waiting for that study.
It seems though as if the genetic risks gods have answered my request, at least with melanoma.
What if we could identify risk and the clinical or medical things we could do to prevent offered no benefit?
Over one hundred patients with a FAMILY HISTORY of melanoma were offered testing for CDKN2a, yes one of the diabetes genes.....
Myriad has this test and it is called Melaris. It turns out ONLY 25 got tested.....so this is not exactly what I call a very powerful study...nonetheless....patients who found they carried the high-risk gene had a significant reduction in scores for anxiety at two weeks after testing. Depression scores were also decreased, and remained so at one-year follow-up.
The Australians are particularly sensitive about Melanoma and it turns out it this case like to "feel" proactive.