Imagine the heartache of losing a 13-year-old son to a mysterious heart problem.

And then being told that the underlying genetic cause was a ticking time bomb in 20 other relatives.

And then having a defibrillator implanted in your other son out of fear and caution. And then watching that boy endure two unnecessary shocks by the device.

And then, after all that, learning that the genetic test results were misinterpreted and the family wasn’t at risk after all.

That’s the cautionary tale Mayo Clinic doctors published last week as a warning to doctors who would race ahead with the latest genetic testing technology without the sophistication to interpret the results properly. It’s a useful lesson for consumers, too, as genetic testing becomes more common.

“This family’s case appeared to be another case of mistaken identity, with wrong conclusions [from] the data ascertained, especially the genetic test results,” said Dr. Michael Ackerman, a genetic cardiologist and director of a genomics lab at Mayo in Rochester.

It’s understandable that a family would search for answers and genetic clues following the unexpected death of a child. In this case, the family (which was not identified in the article) was told that as many as 20 relatives had long QT syndrome, an inherited abnormality that can result in a fast and irregular heartbeat, and can increase the risk of cardiac death.

Mayo doctors have found the condition to be commonly misunderstood. As many as 40 percent of patients who come to Mayo believing they are genetically predisposed to long QT syndrome end up leaving Rochester without the diagnosis.

Such was the case with this family when some of its relatives traveled to Rochester for a second opinion. Under stress and treadmill testing, none of the family members exhibited any signs of the condition, leaving Ackerman to conclude that interpretation of prior genetic and diagnostic testing had been faulty.

“While the technological advances in genetic sequencing have been exponential,” Ackerman said, “our ability to interpret the results has not kept pace.”

A more sophisticated “molecular autopsy” then found that the 13-year-old died from an undiscovered heart muscle condition. And while the condition had a genetic component, none of the surviving relatives shared it.

“This family study highlights … the wrong way of using genetic testing,” Ackerman said, “and also precisely the right way of using and interpreting genetic testing.”