A 13-year-old boy’s sudden death due to cardiac arrest caused doctors to misdiagnose more than 20 of his relatives with a potentially lethal heart disorder in a case that highlights the fact that genetic tests have a possibility to be inaccurate.
The massive scale of misdiagnosis led to the boy’s case which spanned five years to be published in Mayo Clinic Proceedings today, in which the researchers called for a more cautious approach towards using genetic testing tools and a more thorough and careful examination of genetic test results.
According to the study’s researchers, misuse of a genetic test as well as a wrong assessment of the findings resulted in the wrong diagnosis, which led to the boy’s brother being implanted with a defibrillator he didn’t require. The device has since then shocked his heart twice unnecessarily, which led to the family leading to a second opinion on their diagnosis. This is where Dr Ackerman entered the picture.
The genetic test misdiagnosed the family members’ condition as being a Long QT syndrome (LQTS). The condition causes heart to beat abnormally faster and in a more chaotic manner. These rapidly chaotic heartbeats might cause a person to faint or suffer a stroke. In extreme cases, if the heart continues to beat erratically for a lengthy period, it can even result in death.
Long QT syndrome can be passed through an individual’s gene which is why a genetic test was ordered which led to the whole family being misdiagnosed. Dr Ackerman’s one of the specialties is Long QT syndrome, and was unsure about the family suffering from the condition. After studying their medical condition, he came to the conclusion that they did not suffer from LQTS.
Dr Ackerman said, “At one level, families like this one go through intense frustration and anger about the missteps that were made. At another level, there is confirmation with their own gut instinct that things were not hanging all together.”
When Ackerman and his fellow scientists recognized that the boy did not undergo a genetic test, they conducted their own tests and realized that he did not suffer LQTS either.
“Instead, the boy actually died a sudden death from a genetically mediated heart muscle disease due to a completely different mutation that was present in him and him alone,” Dr Ackerman remarked.
Dr Ackerman’s 20-year experience in LQTS leads to his statement that 40% of patients diagnosed with LQTS, who come for a second opinion, do not actually suffer from the disease and are misdiagnosed.
The boy wasn’t tested for actually suffering from the disease. Moreover, test results for LQTS were accepted as being correct even though the family members showed no symptoms of the disease.
For the study, the researchers extracted DNA from the boy and conducted a molecular autopsy, in which DNA was isolated and sequenced in a way that allowed genetic variants to be re-examined and analyzed.
Dr Ackerman mentioned that the case highlights the importance of relying on biodata from an actual cardiac arrest victim and not from a family member. He further added that medical examiners need to rely first on physical markers identified through orthodox tests before conducting a genetic test. When Dr Ackerman discovered that family members had normal ECGs, all doubts of it not being LQTS were thrown out the window.
Why Is LQTS So Frequently Overdiagnosed?
The most common symptom of LQTS is fainting. Whenever a person faints he is most likely considered to be suffering from the condition, whereas in reality a person could faint for a variety of reasons, including dehydration.
Faints are quite common surprisingly. According to Dr Ackerman, about 20-25% of all of earth’s population will faint by the age of 25. Therefore, it becomes tricky separating faints caused by LQTS and faints caused by other reasons.
As the cause of the faint is most likely not investigated properly, it is misdiagnosed as elipsy or ordinary faint. Due to an abundance of ECG tests, the condition becomes overdiagnosed.
A patient’s background needs to be thoroughly investigated, family history needs to be clear and ECG needs to be analyzed crucially to avoid misdiagnosis.
Importance Of Genetic Testing
A lot of diagnoses have started depending on genetic tests because of scientific advancements in this field. Despite this, most genetic tests are not approved by the US Food and Drug Administration (FDA). It has the authority to regulate genetic tests and has only regulated only a few till date, and that too the ones sold as genetic kits to labs.
Genetic tests include a vast array of scientific techniques including analysis of human DNA, RNA, or protein molecules. They are used to diagnose diseases or medical conditions related to specific genes. Genetic tests are also used for non-genetic purposes, such as forensic tests and paternity tests.
In the realm of medicine, genetic tests can be performed to determine the genetic cause of a disease, to confirm a possible diagnosis, predict future diseases, detect when an individual might pass a genetic mutation to his or her offspring, and calculate response to treatment.
In the US, 13,000 lab-based genetic tests are currently available, and they’re given to millions of individuals annually. Yet there’s no guarantee that they work, and the companies that manufacture these tests don’t have to worry since the FDA has no oversight.
The Centers for Medicare and Medicaid Services (CMS) is responsible for overseeing labs conducting genetic tests, while keeping in accordance with the Clinical Laboratory Improvement Amendments of 1988 (CLIA).
CLIA enables to monitor labs to make sure technicians have proper educational training background, proper verification of tests being conducted, strict quality control and proficiency in conducting some specific genetic tests.