Standard disclaimer: None of the advice in this or any other blog post I make is intended as, nor should it be construed to be, medical advice. Consult a trained medical provider knowledgeable in the area of medicine that you want medical advice.
One of the three (3) most popular blog posts on Gini Health in 2018 was https://blog.ginihealth.com/from-lacto-phobes-to-lacto-philes-our-genes-dictate-how-we-tolerate-milk/. I have tested with various DNA testing companies, at least 16 if I include those I transferred raw data from other DNA companies. Of the various DNA tests, some included things like lactose intolerance, risk factors for numerous diseases and medical conditions, other predictions that may or may not have much scientific evidence supporting the predictions. I have also ran my DNA raw data through several websites that give estimates of risk factors.
In all cases, I am shown as “Most Likely Not Lactose Intolerant.” Apparently, my body doesn’t agree with this assessment as I am most definitely moderately lactose intolerant. I love chocolate milk, but I pay the price for drinking it by having to deal with a moderate case of lactose intolerance. In my book, it’s worth the inconvenience. When I was younger, I was not lactose intolerant, but have been for several decades. It doesn’t appear to be getting worse although that’s a subjective opinion as I don’t have anything other than anecdotal evidence supporting my theory.
Taking another example, cilantro/coriander tastes like soap DNA – something I hadn’t heard of before looking at 23andMe’s report on the subject. While the report shows I am “Likely Tolerant,” my taste buds disagree with this assessment. I would eat out and sometimes notice that food tasted soapy. I wasn’t eating at dives so I was confident they were doing a good job washing dishes. However, I didn’t know about how some people’s DNA makes cilantro or coriander taste like soap. Once I read the 23andMe article, it made sense as the items I ate were prepared with coriander or cilantro.
The point here is that the experts wrongly assume a handful of markers, genes, alleles, SNPS, etc. affect a medical condition, disease, etc. It’s pretty common in medical research to assume only a handful of markers cause “Condition X” no matter how rare the condition is. They see a correlation among some markers as being common among patients with the condition and wrongly assume these are the only markers involved in determining if you have the condition. It’s hoped that at some point, they will get enough patients who don’t have the markers that experts will re-think the likelihood they have missed markers.
A good case is schizophrenia; last I checked there were around 250 markers suspected of causing schizophrenia. That’s a lot of markers. In fact, it’s a lot more markers than most other conditions that have known genetic markers. In many cases, it’s as few as a handful, 6 – 10 markers or less.
The above also doesn’t take into account other factors that may happen later in life. For example, if you went from being a non-smoker who had never worked in an environment that was lung unhealthy to a 10-pack/day smoker who now works in a very lung unhealthy environment, then your odds of getting lung cancer will likely be much higher than when you DNA tested before making these two changes. It would be interesting to see how your DNA compares 10 years after you make these two changes to before you made them.
Also, just because you have markers, or absence of known markers, doesn’t automatically mean you will or won’t get the disease or condition. There may be some exceptions, but two comments seen in some DNA forums are: I have the condition, but the DNA test shows I don’t have the markers for the condition, or I don’t have the condition, but I have the markers for the condition. If you don’t have the condition yet, it doesn’t mean you won’t develop it later in life. In most cases, having the markers just puts you at higher risk for developing the condition. Also, if the condition has other factors, you may never get the condition if you make changes now. It’s not a guarantee you won’t get the condition, but if you learn the things that can reduce your chances of getting a condition or disease, you can make changes that may reduce your odds. In my case, avoiding milk and milk-based products could eliminate my lactose intolerance problem. Continuing to drink milk and eat/drink milk-related products may aggravate my lactose intolerance problem.
The other side of the coin is when a study shows that population Z is the group used for the study. If you are of a different ethnic background, the study may or may not hold true for you. In most cases, the 23andMe reports were for ethnic groups I don’t have. In some cases, a condition or disease isn’t limited to only some ethnic groups. In other cases, certain groups have a much higher risk factor. For example, sickle cell anemia and Tay-Sachs are more likely among specific ethnic groups. In other situations, a disease may be more likely among people of a certain age.