Nowadays with a quick swab of your cheek, not only can you trace your family history, but know whether you have a chance of developing diabetes, cancer and other health conditions.
While tracing your ancestral history is quite cool, are genetic tests reliable or problematic at identifying your risk of health conditions? Read on to see how at-home genetic tests work and how they can help you understand some aspects of your future health.
What is a DTC genetic test?
A DTC (direct to consumer) test is a type of genetic screening test that provides reliable information regarding a person’s genes and health. It can detect whether someone is at risk of certain diseases such as Alzheimer’s and heart disease and map out your family history. Many tests can also provide information about your hormone levels, your gut bacteria and what diet suits you best for your metabolism.
However, these tests are not as complete as a genetic test done in a medical setting. Dr Robert Green, a medical geneticist at the Harvard-affiliated Brigham and Women’s Hospital and director of the Genomes2People Research Program quotes “it is important to realize the DTC testing is not the same as genetic testing in a medical context and is not a comprehensive examination of your DNA”.
How does it work?
You order the test online, it gets shipped to you with instructions, you provide cell samples by taking a cheek swab or collecting some saliva in a tube and mail it to the lab. You then await your results, which can be accessed online. Some tests don’t require a doctor’s certificate, while tests such as Veritas Genetics do.
Your risk for developing various illnesses is estimated by looking closely at your DNA. Think of your DNA as a long string of words, these words are made up of a combination of four different letters, the letters can be in different orders. The letters represent four nucleotides; adenine, thymine, guanine and cytosine. The sequence of letters is almost the same for everyone with slight differences, some of which are markers for disease. Scientists can now detect your risk of developing a disease by reading these markers in your genes. Most women who developed breast cancer, for example, have tested positive for the BRCA1 and BRCA2 gene.
How many different types of at-home genetic tests are there?
There are many different variants of at-home genetic testing kits, with one of the most common being 23andMe. 23andMe is well known for tracing your family tree. Now the test offers more than 125 reports and can identify a person’s risk of developing Alzheimer’s or Parkinson’s, as well as coeliac disease. You can discover certain predisposed personality traits too, data about your sleeping patterns, food metabolism and weight.
Did you know that your genes can also influence how your body responds to certain ways of exercising and dieting? This means that your genes can affect your ability to burn fat. The Fitness Genes test analyses 40 genes and over 600,000 gene variants to be able to offer you nutritional advice and exercise recommendations based on your genes.
The NHS offers genetic testing too for people believed to be at risk of certain conditions such as an inherited form of dementia known as frontotemporal dementia. People who have a close relative with dementia or several relatives who have developed dementia younger than 65 years of age will be offered a test. Genetic counselling before and after genetic tests is available with the NHS, something that at-home kits don’t offer.
If you just want advice about what diet or foods are best for your body type, there are tests available that don’t look at your DNA, but your gut. One test called Viome identifies the trillions of active microorganisms you have in your gut with a simple stool sample. Then with the help of AI and expert analysis, the test can recommend what foods you should be eating and what supplements you need for your gut microbiome to reach optimal health. Knowing what foods wreak havoc on your gut is really beneficial as some foods can cause inflammation in the gut which can eventually lead to autoimmune diseases.
How long do you have to wait for genetic testing results?
Results can vary, depending on the test used but are usually posted on a secure online profile within three to four weeks.
The limitations of genetic testing?
Genetic testing kits provide a lot of useful, in-depth information about your health. If you have an illness, you can see exactly what gene is linked to that illness and what lifestyle and diet changes you should make to best match your genetic make-up.
However, genetic counselling is not offered with at-home tests as it is with the NHS, which quite a few people may need if they receive a test positive for a gene related to a serious illness.
Another downfall is that genetic tests are not always complete. The 23andme kit identifies the gene that’s most strongly associated with Alzheimer’s, called APOE, but it doesn’t look at the 20 other possible genes that may also play a role in the development of Alzheimer’s or identify common genes like APP or PSEN1 that have been linked to inherited forms of the disease.
Dr Robert Green says that “genetics as a way to understand disease, create new medications, and predict and prevent heritable conditions is turning out to be hugely worthwhile”, but there are so many different genetic tests and not all of them identify all possible diseases, so tests can be confusing and give incomplete results.
Another limitation is the ability to interpret test results in the absence of a health care provider, that can cause unnecessary stress to some people. A study in the MAY 2017 BMC Medical Genomics found that people who used an at-home genetic testing kit overestimated their likelihood for developing a disease.
There’s also the problem that those who received negative results for a particular disease wrongly assumed that they were in the clear. People take the test and its negative for certain risk factor genes, so they think they are healthy, when in fact they carry other mutations that the test hasn’t identified. Mary-Claire King, University of Washington geneticist fears that women who undertake testing believe they don’t carry a mutation for breast cancer, when in fact they do and consequently could die from relying solely on the results of a genetic test.
Better mechanisms also need to be put in place to regularly update these at-home tests, because pharmacogenetic research is constantly changing and a test that’s out of date can give inaccurate results.
So, is a genetic test a good idea?
On the other hand, genetic tests provide us with information about our health that we otherwise wouldn’t have, so while some tests only show your risk of certain diseases, information about your health and some possible health risks is better than no information at all. A spokesman for 23andMe stated that there have been many cases “where customers have taken a 23andMe result to their doctors, been prescribed confirmatory testing and have had preventative treatment as a result”.
Also, having knowledge about your own health gives you the power to be able to do something about it. You can start to make conscious decisions to optimise your own health and ultimately prevent health conditions that you are predisposed to. As long as you remember that genetic testing isn’t a diagnosis, but rather an overview of your predisposition to certain health conditions.
Join the discussion