What Is a Genetic Test? What It Shows and What It Doesn't

A genetic test reads specific points in your DNA to show whether you carry variants associated with certain traits. In this article we explain what this kind of test can tell you and what it cannot. The aim is to help you make an informed decision about whether to take a test and how to use the result.

What does a genetic test read?

Your DNA is made up of billions of letters, and most of the differences between two people are single-letter changes. These changes are called variants (SNPs). Most consumer tests use a technology called a microarray (SNP chip) to read hundreds of thousands of pre-selected points. They do not sequence the entire genome from start to finish.

At Hub Genetik the process works like this: you take a cheek swab sample at home, send it to the laboratory with the kit, and your report is prepared within 18–21 business days after the sample reaches the laboratory. The details of the method are explained on the Science & Safety page.

What can a genetic test show?

• Whether you carry a variant associated with a trait. A good example is the variant in the LCT region associated with the persistence of the lactase enzyme into adulthood.
• Possible tendencies compared with the average. For example, a tendency to metabolize caffeine faster or more slowly.
• Clues about what you might monitor more closely. A tendency can point to which measurement (e.g. a blood value) may be worth discussing with your doctor.

It is important to know how strong the scientific evidence behind each finding in the report is. In Hub Genetik reports, every finding is given a "strong", "moderate" or "limited" evidence level. You can see what the finding cards look like on the sample report page.

What does a genetic test not show?

It does not show destiny

Most common variants have a small effect on their own. A well-known example is the FTO gene. A large study found that adults carrying two copies of the risk allele were on average about 3 kg heavier than those carrying none. This difference is real, but it is small next to nutrition, physical activity, sleep and the many other factors that determine body weight. A genetic tendency says "may", not "will".

It does not make a diagnosis

The report does not replace a medical diagnosis. If you have symptoms, a family history or a known condition, the assessment belongs to your doctor. A genetic finding does not replace the tests your doctor requests.

It does not replace measurement

A genetic test does not measure your vitamin D level, your cholesterol or your muscle fiber ratio. These are determined by blood tests or clinical measurement. A genetic finding can only show a tendency associated with these values.

It does not reliably detect every rare variant

SNP chips are very good at reading common variants. However, for variants that are very rare in the population, the false-positive rate rises markedly. For this reason, a rare finding that may be clinically important should be confirmed with a separate confirmation test before any decision is made.

It does not measure talent or intelligence

A genetic test cannot tell which sport a child will succeed in, how intelligent they are or how they should learn. The shared view of researchers in sport and exercise genetics is that genetic tests should not be used for talent selection.

How should you use your results?

1. Look at the evidence level. A finding with strong evidence and a finding with limited evidence do not carry the same weight.
2. Combine them with measurement. Compare the tendency with real data (blood values, training logs, sleep patterns).
3. Start with small, reversible changes. For example, moving caffeine to earlier in the day. Observe the effect for a few weeks.
4. Make health-related decisions with your doctor. A genetic report should not be used on its own to start or stop a medication or change its dose.

Which package answers which question?

The packages are organized by the question you want answered:

• For training and recovery questions: Sports & Fitness Genetics
• For preventive health, nutrition response and vitamin–mineral tendencies: Genetic Health Map
• For setting skin-care priorities: Skin Health Genetics
• For curiosity about your origins, with no health content: Ancestry Analysis

To see the packages side by side, visit the comparison page. If you are unsure, the short package finder suggests 1–3 options for you. Other questions about the process are answered on the frequently asked questions page.

References

1. Frayling TM, Timpson NJ, Weedon MN, et al. A common variant in the FTO gene is associated with body mass index and predisposes to childhood and adult obesity. Science. 2007;316(5826):889-94. PMID: 17434869. doi:10.1126/science.1141634
2. Enattah NS, Sahi T, Savilahti E, et al. Identification of a variant associated with adult-type hypolactasia. Nat Genet. 2002;30(2):233-7. PMID: 11788828. doi:10.1038/ng826
3. Weedon MN, Jackson L, Harrison JW, et al. Use of SNP chips to detect rare pathogenic variants: retrospective, population based diagnostic evaluation. BMJ. 2021;372:n214. PMID: 33589468. doi:10.1136/bmj.n214
4. Webborn N, Williams A, McNamee M, et al. Direct-to-consumer genetic testing for predicting sports performance and talent identification: Consensus statement. Br J Sports Med. 2015;49(23):1486-91. PMID: 26582191. doi:10.1136/bjsports-2015-095343
5. Hollands GJ, French DP, Griffin SJ, et al. The impact of communicating genetic risks of disease on risk-reducing health behaviour: systematic review with meta-analysis. BMJ. 2016;352:i1102. PMID: 26979548. doi:10.1136/bmj.i1102