Nature vs. Nurture - DNA and genetic predisposition

This is a bit off of my normal topics, however since a large portion of those who are undergoing autosomal testing are doing so for ancestry composition results or health results, I think it may be of interest to those who read my blog.

First, with a lot of the SNP's identified as increased risk if they are abnormal (polymorphic), it is important to actually look at what the studies tell you. Often it is only a slightly higher risk for a condition, such as some of the markers for gluten intolerance. Having an abnormal marker increases your risk of, but does not necessarily guarantee there is something wrong.

That said, I have a little bit of a rant on one subject. For those of you not scientifically inclined on DNA, SNP's are identified markers on our DNA. Those listed on the various health sites (such as livewello, 23andme, and promethease) have been studied. You can have one of three results on these markers. Normal, (having the normal markers), Heterozygous (one abnormal, one normal marker, means a mixed result) and homozygous (both abnormal). I hate to say Normal is good and homozygous is bad, because even if you are homozygous it doesn't always mean bad. But we tend to think in black and white, so then heterozygous is somewhat in between. Not good, not bad, but a mixture of the two.

There is a plethora of studies out there showing cardiovascular disease is in fact caused from inflammation, most specifically linked to elevated homocysteine levels. These elevated homocysteine levels come from the methylation cycle within our cells. Elevated homocysteine is also linked to Alzheimers and some cancers in research.

You may see something like the MTFHR gene mentioned by some who have done their DNA. It is one gene in the cycle of methylation that focuses on a cause for elevated homocysteine levels. This particular gene affects how our bodies metabolize folic acid. A person with a heterozygous result can metabolize some folic acid (in supplement not natural form). A person with a homozygous metabolizes very little folic acid (in supplement not natural form). It is important to note that estimations are around 40-50% of the population is heterozygous, and around 25% is homozygous for this gene.

However this is just one gene in a cycle that has several steps. The methylation cycle is one of the most important microbiological processes in our cells. By definition methylation is the process of a molecule bonding to a methyl group (a single carbon with 3 hydrogens attached). The methyl group changes the shape and function of that molecule and gives the molecule a new job. A pretty good explanation of it can be found here.

The later pathway of this cycle leads to the production of neurotransmitters (such as serotonin, dopamine, norepinephrine, and epinephrine).  One of the by products is homocysteine, which has gene markers also that have to do with how our body handles it. Homocysteine is a normal by product that the body breaks down when everything is working normally. It is elevated homocysteine levels that cause the inflammation and cellular breakdown linked to many diseases in research.

So what is my rant. Despite knowing inflammation causes heart disease, and despite questionable research on the problems with statins (can cause diabetes, can cause liver problems and not well researched for women. See more here. ) we haven't changed a thing about reducing the inflammation and the cause of the inflammation in our treatment.

Studies about MTFHR specifically have been published for at least 15 years. Yet nothing in healthcare in the United States addresses treatment for abnormalities in this cycle. If it's true as the nutrigenomic proposers state that you can negate some of the effects of these abnormal genes then why hasn't it been addressed? Is it because as a society our medical professionals look down on vitamin supplements as a cure? Is it because in the trend of health care we treat conditions with pathways that are not individualized to the patient?

Now I don't know for a fact, but I suspect many doctors would roll their eyes if someone took their DNA results with their abnormal markers in and asked them about it. It would be one up on the google doctor syndrome that they detest. However, unlike some of the other markers, this specific area, the effects of these genes has been studied pretty significantly, but health care providers aren't trained to interpret these results or offer solutions.

I don't believe that all diseases are strictly nature or strictly nurture. I do think that a little of both is pretty much in play for most conditions. Yet if we are as a profession encouraging patients to eat right, exercise and be proactive in their health, why would we ignore a potential pathway to improving their overall health throughout their lifetime?