Is Your Genetic Testing Accurate? Understand the Accuracy of Genetic Testing


Health-related? Non-health related?

There are genetic testing services with different purposes available in the market for the consumers. They can be classified into health-related genetic tests and non-health-related genetic tests. [1]

Genetic testing for ancestry, talents, athletics performance, nutritional needs are non-health-related genetic tests. Even though the data analysis process of non-health-related tests is handled properly, their credibility might still be affected by the way they interpret the test results. The above-mentioned phenotypes are affected by multiple factors. Apart from complex genetic factors, they are also affected by the environment, lifestyle, and aging. Therefore, the accuracy of non-health-related tests is generally low. [1]
Complex phenotypes
Health-related genetic tests could be for medical reference usage. There are many genes found to be related to the heredity of diseases. Genetic testing can help with the diagnosis of hereditary diseases. Some other common diseases, such as cancers, cardiovascular diseases, diabetes, might also have a certain level of heredity. We can understand its heredity through genetic testing. Genetic testing is also beneficial to therapy options. For example, pharmacogenomics helps with adjusting drug options a drug dosage for optimal treatment outcome, and genetic testing for targeted therapy can help guide the type of treatment for cancer patients. As long as using professional technology and analysis based on scientific research references, health-related genetic tests are significant to personal health.

Since the health-related genetic tests are for medical use, their accuracy brings our concerns. There are two potential issues raised by health-related genetic tests. First, are there any data errors from DNA sequencing? Second, is data analysis from sequenced DNA creditable?

Are there any data errors from DNA sequencing?

DNA sequencing is the process of determining the order of nucleotide bases (A, C, T, G).

After getting a qualified testing sample, laboratory technicians would go through the procedures of DNA extraction and library preparation. After that, it will be the DNA sequencing process with a DNA sequencer. The processes require professional technology supports from laboratory technicians so that there will not be any mistakes in the manual processes.

Once the samples pass to the DNA sequencing process, it is required to pass certain standards before entering the data analysis process.

Is data analysis from sequenced DNA creditable?

Even if it is ensured that the sequencing process is handled properly, the data analysis process plays an important role in determining the accuracy of genetic testing.

Bioinformaticians arrange the DNA sequence for DNA alignment. This is a step to identify similarities and differences in the DNA sequence. Variants, such as insertion mutations or deletion mutations, can be identified from the arranged DNA sequence. This process is called variant calling. After that, bioinformaticians would assign functional information to DNA variants for variant annotation. It is to find out the relationship between identifies mutations and diseases.

Every step above is affecting the accuracy of genetic testing. It includes manual, equipment, and technology factors. When considering the accuracy of a genetic test, all factors should be considered.

Medical error caused by inaccurate genetic testing

There was news reported that brothers from the same family suffered from muscular dystrophy, both passed away within 4 years. [2] We can understand their parents have a family background of muscle dystrophy from the news clip. Therefore, they decided to have genetic testing after their marriage, to ensure they do not have the inherited pathogenic gene to pass to the next generation. The testing result was negative. However, both of their kids were onset at the age of 6 and 8 respectively. The genetic testing result was wrong at that time obviously.

Not just in Hong Kong, there are medical errors caused by inaccurate genetic testing in the United State. A mother tried to find out the cause of epilepsy of her daughter with a genetic test. However, the genetic testing company failed to find out the pathogenic mutation. Her daughter passed away three years after. [3] A few years later, the mother decided to have genetic testing of her own for a birth plan. She asked for the test report for her daughter from the genetic testing company at the same time. She found her daughter’s test result was being revised. The result has shown that she had Dravet syndrome, a rare form of epilepsy caused by a genetic mutation. The inaccurate test report resulted in the wrong treatment option. The treatment plan would be different if her daughter being diagnosed at that time.


[1] Department of Health, “Information Leaflet on Direct-to-consumer Genetic Tests”

[2] 【胞兄同病離世】14歲肌萎少年猝死 父傷感:兩兄弟已經一齊了

[3] HGMD and ClinVar: Avoiding the Knowledge Blind Spot