DNA testing is no longer confined to specialist medical clinics but is now commonplace in healthcare and consumer goods. Genetic testing is becoming more common in Australia for assessing disease risk, screening for inherited conditions, ancestry and for gaining personalised health information. Over the last 20 years, with the introduction of genomic sequencing technology, genomic testing has become much cheaper from tens of thousands of AUD to as little as a few hundred dollars. In spite of increasing availability, the interpretation of one’s results from his or her DNA is challenging. Genetic results are frequently given in probabilities, not absolutes, and this can cause confusion as to what a positive, negative or unsure result implies. It is important to have an understanding of the science of these common DNA tests, as the genetic information may impact long-term disease prevention plans, family planning, and health care options.
There Are Various Types of DNA Tests in Use Today
There are three types of DNA testing overall: diagnostic DNA testing, predictive DNA testing, and direct-to-consumer testing. In clinical situations, diagnostic tests are employed to detect individual genetic disorders. Consumer DNA services tend to be more for ancestry and general health characteristics, while predictive tests estimate the possibility of getting diseases later in life. The rise in consumer uptake of “direct-to-consumer” genetic testing has spurred many to consider home genetic reports for health-related areas, without the involvement of a doctor. In Australia, the growing trend of at-home genetic testing has been accompanied by many consumers wishing to consider health-related genetic reports without sitting down with a doctor. The DNA health test could evaluate genes linked to diseases like heart disease, familial cancers or reaction to treatments. But, typically health-related consumer tests only look at specific genetic variants and do not analyse the entire genome, giving only a partial view of someone’s genetic makeup not a full health report.
What Are Disease Risk Results?
A crucial area of DNA testing that is misunderstood is the prediction of disease risk. Numerous genetic reports may offer a relative risk instead of a diagnosis. For instance, having a predisposing genetic change to a disease does not mean that the disease will happen. It has been demonstrated that the inheritance of genes varies between different diseases. Lifetime cancer risks may be significantly increased for people with hereditary cancer predisposition syndromes (e.g., those associated with variants of the breast cancer susceptibility genes BRCA1 and BRCA2). But with common diseases like hypertension, heart disease, and obesity, genetics only play a small role in an overall profile of risk. Other environmental factors, lifestyle habits, diet, physical activity and age often are as important.
Recognise Variants, Mutations and Uncertain Findings
When there are findings, the report from the DNA will typically group them into one of the following categories: pathogenic variants, likely pathogenic variants, benign variants, and variants of uncertain significance (VUS). Such classifications can have a major impact on the interpretation of results. A pathogenic variant is a variant that has good scientific evidence connecting it with diseases. A variant of uncertain significance, on the other hand, is one that, at this time, scientists are unable to conclude if it has any impact on health. In the clinical genomic programs, the results come as uncertainty most of the time. Millions of genetic differences are found within a single person, but at the present time, a small number are known to have medical significance. With growing genomic databases, some ambiguous variants are re-evaluated. This implies that a person’s understanding can alter over time due to new scientific information.
Consumer DNA Testing and The Accuracy of The Tests?
Many consumer DNA testing companies boast that their testing labs are highly accurate, often with returns greater than 99% correct for one or more of the genetic markers. But this doesn’t mean that analysis is the same as being useful in practice. Even with a highly accurate test, there may still be insufficient information to predict overall health outcomes. Australian health officials have stated several times that many of these direct-to-consumer genetic tests analyse only specific variants and don’t detect all of the clinically relevant genetic changes. Moreover, the significance of the same genetic information may vary among various companies depending on the reference databases they use. Other experts have pointed out that some of the new consumer genetic products that claim to act upon more complex traits like intelligence, sport abilities and personality have poorly documented scientific evidence. The power of prediction provided by these tests may be very modest since these characteristics are not controlled by a few distinct DNA markers but by thousands of genetic and environmental characteristics.
Why Is Family History More Important Than Many Test Results?
Another false belief is that DNA can substitute for the doctor’s medical history reviews. But, actually, family history is one of the best predictors of many inherited conditions. Information from relatives, disease patterns, age of onset of disease, and environmental exposures is often used in combination with DNA findings by clinical geneticists. A person who has a negative genetic overview but has had several members of their immediate family with the same illness, for example, may be at a higher disease risk. Results from public health genomics programs show that family history can provide patterns of inherited risks that current genetic technologies do not identify. This is especially critical due to the fact that not a lot of the genetic variations that are associated with disease are identified or comprehended. The healthcare community has generally adopted DNA testing as a part of a more comprehensive risk assessment process, not as a standalone test.
