Monday, September 24, 2007

Want Longevity? Quit smoking and eat less.....

Yes, quitting smoking and eating less can help you. But it turns out some people will have an easier time doing these things. Also of note we begin to prove Murphy's Hypothesis (There is no such thing as a mongenic disease) These recent genetic studies caught my eye last week.

The first of this is sentinel study (Warning, all sentinel studies require replication)
This study reveals that patients with changes in the Cytochrome P450 enzyme 2B6. It turns out that"individuals with the CYP2B6 6 allele of the gene benefited from bupropion treatment and maintained abstinence longer while doing poorly on placebo, with a 32.5% abstinent rate vs. 14.3%, respectively. In contrast, those in the CYP2B6 1 group did well on both bupropion and placebo, with similar abstinence rates at the end of treatment and after a six month follow-up"

True that we do need some replication on this one, but there does seem to be other literature indicating this trend and other polymorphisms in Dopamine Receptors as well.

In addition to this one an article came out in AJHG this week. I want everyone to give up these words "MonoGenic Disease" Why? There is no such thing as a monogenic disease, unless you only have ONE GENE in your body. An example of this dichotomy is seen in the MONOGENIC DISEASE Hemochromatosis (Which BTW is not monogenic)

Unfortunately most Hemochromatosis is caused by mutations in HFE, but despite this testing, there are still people with Iron Overload who do not have HFE mutations. This is why I am not an advocate of HFE screening or even DTC testing of HFE. Even crazier, different people with hemochromatosis present differently. Why? Because there is no such thing as a MONOGENIC disease!!! In the AJHG this week an article shows that common variants in 3 other genes affect the penetrance of hemochromatosis. These genes are BMP2, BMP4, and HJV.
Serum ferritin levels were all affected by these common SNPs.There was even some indication of synergy between genes. To translate-Hemochromatosis is a multigenic disease, which primarily has problems in the HFE gene. So now is that clear as mud? The point....Don't expect a DTC test for hemochromatosis to tell you 1)If you will have Iron Overload 2)How bad your disease will be.

Finally, before you fall asleep or your heads explode, I want to chat about longevity. Some people think longevity can be bought with hormones, others with vitamins and Nutraceuticals (actually there is better data here). One big group thinks that all we have to do is stop eating.

This starvation group has recently been vindicated by studies on a family of genes called Sirtuins. A recent review was written in the Annals of Medicine. But just a couple of days ago an article in Cell the guys from Harvard Path publish on the role these genes play. Warning. This is a science heavy paper and the clinician may not find it useful at all....Dr Hsien Lei actually posted on this article as well. I see this as a potential windfall for companies looking to create Sirtuin activating cereals..........

The Sherpa Says: Gene Genie is up at Neurophilosophy so check it out! I am tuning up to host the next! We have along road ahead of us.....I like the way we are headed. However, there are some big bumps and changes coming up. Let's all keep our eyes on the prize...Truly Personalized Medicine

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