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Genetic testing and potential harm: DTC or trust me I’m a doctor?

Recently at a couple of conferences (European Human Genetics conference and Consumer Genetics Conf) there have been various speakers questioning DTC genetics and calling for all health related personal genetics to be delivered through medical practitioners. I argued in the past that unregulated tests delivered through practitioners actually have the potential for more harm, not less. By coincidence last week some discrepancies in a DTC and a via MD test were pointed out to me – and they seem topical. Breast feeding has many benefits one of which appears to be increased IQ scores – however not all studies agree, some indicating that results may be confounded by maternal intelligence (see Wikipedia). Sometimes inconsistencies in associating an action with an outcome can be resolved by looking at genetic variation (which tends to increase the error bars when not accounted for). So in 2007 some headlines were made when a study was published by Caspi’s group (PNAS, open access) reporting …
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If You Want to Practice Evidence Based Medicine then… Use the Evidence

Travelling on a train to Scotland, all for the first time:


Clinical researcher says: "Look the cows in Scotland are black!".
Physicist replies: "No. Some of the cows in Scotland are black"
Mathematician says:  "No, actually in Scotland there is at least one cow black on one side"
I’ve written about folic acid, homocysteine and various clinical trials of nutrients in the past. I just want to revisit it briefly because I think there are some seriously wrong messages emerging from the conclusions. For an excellent comment on evidence based recommendations see Colby Vorland.

Homocysteine (Hcy) is associated with CVD, may or may not be causal but the evidence is good (Wald et al, BMJ, 2002). Folic acid (Vitamin B9) in reasonable amounts will lower homocysteine  but clinical trials have been carried out, mostly showing not much benefit as far a CVD is concerned. A recent meta-analysis of 8 trials (total 37,485 individuals) seems to confirm this: “Dietary supplemen…

Breast feeding: Personal genetics is in it’s infancy…

There is a lot in the new today about breast feeding – should it be exclusive for at least 6 months (WHO) or should it include some earlier introduction of solid foods (BMJ article)? A lot of the reporting is confusing the issue, claiming or implying that the BMJ authors are saying the 6 months is too long (and pointing out that they have been consultants to the baby food industry). The BMJ authors are not saying that, they simply say that it might be prudent to introduce gradually some solid foods, while still breast feeding before 6 months.There is a useful account at the Marion Nestle blog and I left a comment there which I have expanded upon here. This could be an area where genetic testing can help – blanket advice is never the best for all but confusion (as we have now) is even worse. I blogged about celiac disease and genetic testing a while ago and part of the post addressed exactly the issue of breastfeeding and weaning....babies differ! Probably, very likely, one type of adv…

The Great Health Data Deficit: Are Environmental causes for Disease a Mirage?

Ever since I was a child the message has been eat your greens (we got caned at primary school if we didn’t), you need to exercise, carrots will make you see in the dark, an apple a day keeps the doctor away. It continues today with the “5 a day”, all the healthy food pyramids, anti-junk foods, and so on. Yes the environment can be dangerous, it can kill us. There are some indisputable examples, a bullet in the head for example, or getting hit by a car is an environmental impact that almost always results in injury and death. There are others on which we more or less agree, like smoking is harmful (evidence is very strong, although it has never actually been proven, who knows, it could be the regular movement of hand to mouth that causes all the damage, we need to do the proper controlled trial…)For the rest we have always sort of somehow known that eating badly can cause disease – it seemed so obvious, and all the little research studies just confirmed what we knew and lead to the ris…

Personal Genetics & Utility: Round 2 – Mind the EGAPP

Yesterday I wrote about the false Family History vs. Personal Genetics battle, today I look at the old chestnut of traditional risk factors. There seems to be a lot of fear among some professions that personal genetics is attempting to take over their jobs – it’s been like this from the beginning mainly due to misunderstanding (wilful or otherwise) exactly what personal genetics is and what it’s role in healthcare can be.
The latest salvo is from the EGAPP Working group who published their assessment of genetics vs. traditional risk factors (TRF) in cardiovascular disease risk. They looked at the 9p21 variant as well as 57 other variants in 28 genes associated with CVD and they sought to document
“the extent to which genomic profiling alters CVD risk estimation, alone and in combination with traditional risk factors, and the extent to which risk reclassification improves health outcomes”. Some conclusions from EGAPP:
The magnitude of net health benefit from use of any of these tes…

Personal Genetics has a Family History of getting beaten up

Over the last few days personal genetics has come in for a bit of a bashing, first it was knocked out by family history then it was clearly nailed into the coffin by traditional risk factors.Also have a look at Genesherpa’s blog for some more putting the boot in here and here.Update: Nov 12th, here is the 23andMe blog on the subjectBut what is behind the hype and the headlines? In this post I will look at family history and deal with EGAPP in the next.The latest attack was sparked by a press release of some work presented at the ASHG. We don’t know too much because all we have is an abstract and a video but we have enough. FH was compared to the Navigenics genetic profile (PGS). From the abstract“None of the 3 hereditary prostate cancer subjects were assessed as high risk on PGS. Based on FHRA, 10 subjects had hereditary breast cancer risk and PGS only identified 1 as high risk (K=0.12). None of the 9 hereditary colon cancer subjects were high risk on PGS.”Sounds awful and this was th…

Nutrigenetics–a little bit of history, but no miracles

Reading The $1,000 Genome by Kevin Davies, as expected it’s a fascinating story and right at the beginning in Chapter 1 there was something that I liked. The first personal genome to be sequenced and interpreted was that of Jim Watson (Craig Venter was first but no interpretation). Davies describes the presentation of Watson’s genome to the man himself and reports that the sequencing was performed by 454 and the interpretation was handled by the team directed by Richard Gibbs of the Baylor Genome Center. Watson’s genome inventory, for example, revealed 310 genes with likely mutations and 23 with known disease causing mutations, increasing his risk for cancer and heart disease. The Baylor team recommended that he should take folic acid and other vitamins and minimize his exposure to sunlight, particularly during his daily tennis matches. p19So there you have it, the first advice based on the first interpretation of a human genome sequence was nutrigenetic!But then I read later in the b…