That night in November 2017 was like so many others for Dallan Isom, a 29-year-old father from Bountiful, Utah. He played basketball with some friends to relieve stress, and around 10:30 he was getting into bed and told his wife Sam, who was five months pregnant at the time, that he felt like his heart was racing. He attributed it to basketball (and maybe getting older and a little out of shape) and went to sleep.
Less than three hours later, Sam woke up to Dallan making a strange groaning noise. “He has some vivid dreams, so in the dark I thought maybe he’s just having a nightmare,” she said. “I called out but he didn’t answer me, and that’s when I knew something was wrong.”
Dallan was having a heart attack. Sam called 911, pulled her husband—now unconscious and not breathing—onto the floor, and was preparing to start CPR when emergency responders arrived. After 26 minutes of CPR and four defibrillator shocks, Dallan was transferred to a nearby hospital, and eventually flown to University of Utah Hospital.
Dallan doesn’t remember much of that night, or the days following, but Sam remembers that while they were able to get Dallan’s heart beating again, medical providers were concerned he could have brain damage.
Doctors thought he might have long QT syndrome, a genetic cardiovascular condition that disrupts the heart’s electrical rhythms, causing irregular heartbeats called arrhythmias. This condition is often exacerbated by exercise or high stress levels, and in rare cases can result in a sudden cardiac event. But doctors didn’t want to rule anything out, so they recommended a DNA test to find out if his genes could shed light on the cause of his heart attack.
“The first time I met Dallan he was unconscious, so I actually met with his wife at his bedside,” said Katelyn Swade, an adult cardiovascular genetic counselor with University of Utah Health. “We were asking Sam if she wanted to try [the genetic test] to help us better understand what did happen.”
Those results came back several weeks later with information that surprised everyone. Not only did Dallan have long QT syndrome, he also had a genetic cardiovascular condition called hypertrophic cardiomyopathy (HCM), where the heart muscles enlarge, causing the walls of the heart to thicken and block normal blood flow.
Both long QT, which affects about 1 in 2500 people, and HCM, which affects anywhere from 1 in 500 to 1 in 200, and is probably underdiagnosed, according to Swade, are known genetic mutations that occur on chromosome 11. Because they occur on the same chromosome, it’s rare for someone to have both; about a one in a million chance, says Swade. Dallan had inherited the long QT from his mom and HCM from his dad.
Knowing that he had both, the next step was to perform DNA tests on his immediate and extended family to find out who else had HCM and long QT. Neither his parents, nor any of their relatives were aware they had the conditions.
“On his mom’s side already 10 people have been diagnosed with long QT,” said Sam. That includes the three-year-old daughter of Dallan’s cousin who was showing symptoms of long QT but, unaware of the genetic family history, doctors had not been able to diagnose it.
Another unique situation that genetic testing revealed was that since Dallan has both conditions, and they are on different genes on the same chromosome, there is a 100 percent chance each of his sons will inherit one or the other, but not both. The family decided to get genetic testing for both sons and learned that the older boy has long QT and his younger son has HCM.
“I don’t know if there was a way for me to have avoided [the cardiac arrest] or prepared for it,” said Dallan. “Without knowing of any family history, the only way that I could have known about this was genetic testing really.”
For Sam, finding out that her boys were definitely going to have a genetic cardiovascular abnormality at the same time she was helping her husband recover from his own near-death experience was stressful, but reflecting back on it now she is grateful that genetic testing has provided more information.
“I think often about what could happen to my kids if we didn’t know,” said Sam. “I feel like it saved my kids lives—as scary as it is that my kids have these conditions, I know that we’re treating it and they can live long, healthy lives.”
Today most of Dallan’s life has returned to normal. He’s back to work, raising two young boys, working out and playing basketball. He is on beta-blocker medication to help prevent another sudden cardiac event, and gets scans once a year to check on his heart. He also has an implanted defibrillator that, if it detects a potentially dangerous arrhythmia, will shock his heart back into normal rhythm.
“Definitely it feels good to be able to get back into being active, as long as I’m tracking things and being conscientious, I have the confidence to live the life that I want to live,” he said.
Family members on both sides of Dallan’s family are also now getting regular screenings and scans to protect them from adverse cardiac events, thanks to genetic testing and counseling.
“The genetic counselors were so great and they made it so easy for us to take these tests,” said Sam. “We were lucky, we’re so blessed that he survived, but there are so many people out there who don’t survive. If I had my way these genetic tests would be given to everybody.”