DNA testing: What does it show?

Updated on March 20, 2022

DNA testing or genetic testing has become routine. It has expanded from genetic screenings of newborns for common disorders and paternity testing to predictive and diagnostic genetic testing for adults. But what does DNA testing show? The answer is: it depends on the test. 

Genetic Tests for Medications 

Genes do not exist to create disease. They create proteins. Every person’s genetic makeup is different, and the variation in the genome is partially driven by the need to have a diverse population so that we can better resist diseases and parasites. On the other hand, this results in a diverse array of reactions to medication and differences in how our bodies react to specific drugs. This is why genetic tests exist to determine which psychiatric and pain medications are most likely to be effective for you and which you should probably avoid.

Note that the genetic potential is very different from an allergic reaction to a drug because of an immune system response. 

Nutritional Testing 

DNA testing has some potential when it comes to diagnosing and managing nutritional issues. We all obviously need to eat a healthy diet. However, there are health risks and tendencies that determine what our own, personal definition of that would be. For example, someone with high risk of osteoporosis may want to increase their calcium and vitamin D intake. If your body There are genes that cause people to have unusually high or low iron levels, and you may need to alter your diet to make up for that. Knowing that you have a tendency toward diabetes could lead to a diet plan that limits blood sugar swings as well as helps you lose weight.

Note that genetic nutritional testing is only a rough guideline. It won’t diagnose insufficient hormone production by the thyroid or pancreas. Furthermore, genetic testing is sometimes used to push nutritional supplements supposedly tailored to you though they’re simply something that fits your demographic. For example, the testing company may recommend that an older women of European or Northern Asian descent take calcium supplements because her ancestry increases her risk of osteoporosis. 

Genetic Genealogy 

One of the first popular forms of genetic testing was paternity testing. Up to a third of the men who questioned paternity were not the biological father of the child in question. Note that this is a small fraction of the population at large.

Genetic genealogy often looks at the same SNPs and other highly personalized genetic markers to find your closest biological relatives. That has been used for everything from helping adoptees find biological parents to allowing family trees to trace their ancestry back several more generations. Newer genetic tests allow you to find those who share the same mitochondria, genetic code inherited only from your mother, and the same Y-chromosome. The former is sometimes the only way to identify the true background of a war-bridge.

The genetic tests that purport to identify your ethnic makeup are less reliable, and you can get wildly different results depending on which company you do the test with. The tests are less accurate if you have an unusual ancestry. The genetic genealogy companies are trying to gather more pure genetic samples of diverse populations to get more accurate results, instead of telling people with partial Native American ancestry that they are part Japanese. 

Genetic Testing for Specific Disorders 

These are the most accurate genetic tests available. Do you or do you not have the gene for cystic fibrosis, sickle cell disease or Tay Sachs? Diagnostic genetic tests for genes that dramatically increase your risk for certain conditions have become popular. For example, many women are getting tested for the BRAC-1 gene that significantly increases your risk of developing breast cancer. 

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