Strong is your hold O mortal flesh . . .

From The Last Invocation, Walt Whitman

Is it just me, or are you also getting a bit tired of all the hype about the genome? Don't get me wrong-- it's pretty incredible that in my lifetime we have mapped out the 25,000 plus genes in our DNA. What's even more amazing is that the price for that chart of the human genome has gone from millions to less than $50,000 and now it takes only a few weeks. I bet by next year it might be a few hundred dollars and take a day! Companies like 23andMe (an innovative venture with a great marketing plan) offer to check you for genetic markers that predict your risk for certain diseases for just a few hundred dollars.

But the fact remains that for most of us, the genotype is much less relevant than the phenotype. What is phenotype? It is the things we can see, the outward or observable physical or biochemical characteristics and they are determined by both your genetic makeup and environmental influences. Your blond hair, your weight, your strange nose, green eyes and that funky shaped little toe of yours --all examples of phenotype.

So what do I mean when I say phenotype is more relevant than genotype? Well, let's say a new patient, a male, walks into my office and he is in his fifties. Let's say he happens to have the outline of a pack of cigarettes showing in his front pocket. As a male he already has one risk factor for coronary artery disease--just being male, alas. The cigarettes tell me that he is four times more likely to have a heart attack than his peers who don't smoke. His risk of sudden death is at least doubled. Let's say I notice he happens to be carrying more than 30 pounds of extra poundage above the belt line: that allows me to predict he has a higher chance of being at risk for diabetes, if he is not already frankly diabetic. Let's say that I notice too the pale outline of a recently-removed wedding ring (I can't help it, my eyes are always looking at the body as text--even when I am out of the hospital), then I know that his risk of death as a recently divorced man can be double that of his married peers.