In between televised Olympic coverage this week, the commercial for ’23 and me’ has been one of my favorites. It starts looking all the world like a car ad; asking you what car you’d pick if you could only have one car for life. They then remind you, half way through romantic American landscape footage, that while you will likely have many cars in your lifetime, you will only have one body and it’s your job to take care of it. What a compelling explanation for exploring your genetic makeup!
Our understanding of genomics, or the study of our human genes, has accelerated quickly since scientists completed coding of the human genome in 2003. We now have many different genetic testing options to look at one or almost all of our genes and interpreting the results is rarely straightforward. While ’23 and me’ may be one of the most recognized testing services, it is certainly not the only one.
As for the “most recognized gene”, that award most certainly goes to MTHFR. In part because the enzyme that this gene codes for is involved in so many important reactions in our body and in part because its 5-consonant acronym suggests the coming of an expletive, this gene is often the first one we learn about in any foray into genomics. In fact there are many other possible gene mutations (known as SNPs) worthy of exploring, but the MTHFR gene alone can prompt many questions and avenues of inquiry. One of the most prominent authors and educators on clinical applications of genomics, Dr. Ben Lynch, has an entire website devoted to this one SNP:
So what does this gene do? As I mentioned, it codes for an enzyme called methylenetetrahydrofolate reductase….I know, quite a name! This enzyme is involved in methylation – adding a methyl group (a carbon with three hydrogens attached) to folic acid, converting it to its active form so that the body can use it. This is so critical because methyl-folate, the product of this reaction, is involved in so many processes in our body. Which bring us to the first key factoid about this gene and its possible mutation. Remember how you were always told to take folic acid to prevent birth defects when and if you got pregnant? Well, it turns out that if you do have a mutation in this gene, folic acid may not be all that helpful because your methylenetetrahydrofolate reductase may not be up to converting it into its active form. If you’re homozygous for this SNP (more on this in a sec!), it can actually be harmful because that folic acid will build up, not being put to use through the process of methylation. Consequently it’s a much better idea to take that folic acid when it’s already in its active form – called 5-MTHF or quatrefolate or folinic acid. So if you’re taking a multivitamin, go check it now! I highly recommend switching any folic acid that you’re taking to its active form. Unless you’ve had genetic testing done, you may not know if you have a mutation in this gene that would challenge your folic acid methylation, but it can’t hurt to switch to supplementing with the active form, supporting this critical pathway in the process.
So back to my mention of a homozygous SNP. Since every gene has two alleles coding for it (one from Mom and one from Dad), when looking at your genes through testing, each gene tested will either by identified as homozygous normal (also referred to as “wild-type”), heterozygous (meaning you have a mutation on one allele but not on the other) or homozygous for the mutation (which can be referred to as a SNP – a single nucleotide polymorphism). If you are homozygous wild-type for a particular gene, it means that your gene will code normally. Many, many genes code for enzymes which then help all the chemical reactions in our body to happen. So if your gene is functioning “normally”, it will produce the enzyme it’s supposed to and the reactions that use that enzyme will move forward at the rate they’re supposed to (barring any nutrient deficiencies or toxicities).
The SNPs and our preventative health efforts come into play when you are either heterozygous or homozygous mutant for a particular gene. A heterozygous SNP may not present much of a problem. It may cause a pathway to move a little bit more slowly but with the necessary cofactors (here’s where the healthy diet comes in), the reaction can proceed. The homozygous mutant SNPs, on the other hand, are the ones where knowledge can really be power. This is why genetic testing may be insightful for some people. When you have a homozygous SNP (or mutation), the pathway that uses that enzyme product may not function and alternate routes to the end destination may be discovered by the body. Depending on which gene we’re talking about, this alternate routing system may be rather insignificant or may be more noticeable if that process plays a critical role in the body’s daily reactions.
Let me clarify, however, that this is not as scary as I’ve made it sound. I know the word mutation doesn’t sound all that healthy, the reality is that we all have SNPs in our genes. These SNPs can, in some cases, predispose us to certain health issues or diseases, but they are also involved in creating our unique characteristics and in some cases can even confer protection against certain diagnoses.
While genetic testing is not necessary for all, looking at what’s happening with your genes can be enlightening, especially if you have some health issues that are not complete understood or you have a strong family history of a certain condition that you want to be proactive about. But your genes are not your destiny. So any information that you learn from a genetic test should be considered with perspective on the importance of epigenetics. Epigenetics are the substances that turn your genes on and off and may influence how significant a SNP is to your overall health. While we can’t choose our genes, we can significantly influence them through epigenetic mechanisms. I’ll explain all things epigenetic in my next post, when the Olympics are over!
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