Introduction to Genomics
Genetics is changing the face of modern medicine. Many patients are now keen to test their genes to see what diseases they are at risk of, what medications suit them best and to tailor their medical care as best as possible to who they are. Genetic tests are increasingly being used in day to day medical practice; this might be to test for well known genetic diseases or to gain more knowledge into the nuances of how your body functions. There are some tests that are more valuable than others and we shall discuss what to expect.
Testing
Genetics is the study of individual genes whilst genomics is the study of an entire genome; or a person’s entire set of genes put together.
Nutrigenomics is the study of the interactions of genetics and nutrition and the impact on human health. Some of the sets of genes that are examined include:
- Oxidative stress; chemical reactions that damage our cells
- Methylation: an important process using vitamins for cell functions Human Leukocyte Antigen (HLA) and celiac: gut allergies
- Food responsiveness
- Bone Health
- Insulin Sensitivity
- Inflammation
- Lipid (fat) metabolism
Pharmacogenetics assesses how somebody’s genome influences how they respond to drugs. At present, drugs are prescribed by doctors in a ‘one size fits all’ model; however we know that different people respond differently. Genes can be assessed to:
Determine if some medications are broken down faster or slower than other people
Determine if some drugs cannot be broken down at all
Determine if some drugs are broken down in a way that causes toxicity or interactions
Help doctors personalise and become precise in choosing treatments Minimise the chance of toxicities
Choose the best possible drugs for you
What kinds of genetic tests are there?
There are many genomics tests on the market. Some of these tests are very comprehensive in testing for many variations of a gene and some will only test for the most common variations of a gene of interest. For that reason, testing for serious disease related genes (breast cancer genes or cystic fibrosis) is best done by an accredited pathology laboratory so that things are less likely to be missed.
Genomics testing aims to assess the genomics profile related to sets of domains of interest that underlie structure, function and metabolism that may be related to certain processes of interest in the body. This may include looking at genes that are associated with the following:
- Metabolism of food
- How drugs are metabolised
- Fuel during exercise
- How you process caffeine
- Repair of tissues
- How you get rid of certain fats
- Diseases like thin bones or dementia
- IA risk for sun damage or skin cancer
- Genes associated with inflammation
- Variations in the genes that process hormones
This list is not exhaustive. Furthermore, it is worth noting that not all genes that might be behind these situations in the body can be found and tested for and having these genes does not necessarily mean that you will automatically get these problems; it just points out that there is an association.
Some genes that are found are described as being ‘variations of uncertain significance’. For this reason, it is always best to have your genomics test in
conjunction with conventional health check bloods and discuss with a doctor rather than a company representative.
Why would somebody get a genomics test?
Many people will seek to get a genome test to understand more about themselves, how their body works and also in conjunction with a full body health check. Often the genomic test helps yourself and your doctor understand why your health check looks the way it does. Also, the information from the genomic test can help you better target your diet, exercise, medications and lifestyle to get a better outcome for your goals.
What genomics tests are available?
At current, genome testing packages are grouped in certain themes. Genetic tests tend to cluster on looking for variations in the following areas:
- Diet and metabolism
- Pregnancy related conditions
- Detoxification and how your body gets rid of unwanted chemicals
- Heavy metals processing
- Stress resilience and oxidation
- Bone health
- Factors for healthy aging
- Sports and training genes
- Inflammation and workout recover
- Caffeine metabolism
- Muscle formation and function
- Carbohydrate responsiveness for fat metabolism
- Fat storage
- Circadian rhythm and sleep
- Mental health and alertness
- Neurodegenerative disorders
- Mood disorders and addictive behaviours
- Skin health
- Allergies
- Drug metabolism
How useful are these tests and when should I use them?
Only a handful of genetic tests give us a clear and easy result.
Whilst there are some genes that clearly cause disease (like haemochromatosis, a genetic iron storage disorder) much of our genetic code is inactive, or partially active and produces the total outcome together with a heap of other factors.
In this case, the results of a genetic test are best interpreted in light of the total picture so that a weighted decision can be made on how likely the genetic testing is representing your health.
In particular, many of the new genetic test packages are designed solely for commercial purposes and are not thorough enough to be relied on for diagnosing an important medical illness. Often the DNA test companies will test a handful of the common gene variations for a matter, but not all of them. This means that important, but rare genes that still matter can be missed.
In one famous case, a woman was told that she had no genetic risk factors for breast cancer but a more thorough DNA analysis found several others important genes related to breast cancer that were not tested for.
Overall, genetic tests can provide useful information about your health, but not all genetic tests are equal. In my experience, a genetic test done for a serious or suspected condition should always be done by an experienced and accredited diagnostic laboratory, and for more curiosity driven lifestyle and broader genetic tests, it is best to speak with your doctor about the results and perform other tests to challenge whether the results actually turn up in your health or are just incidental findings.
The best way to do a DNA test is to make sure you get a proper diagnostic DNA test for conditions that matter and otherwise to get a proper diagnosis to interpret more random ‘off the shelf’ DNA tests to see if the results matter. This way, you can put the picture together as a whole.
