My TK2d Diagnosis Story

Art Estopinan Jr., age 14, leads a busy life. He attends school, takes part in drama club, and plays soccer and basketball with his classmates. Like any teenage boy, he plays video games like Roblox on the weekends.

But life for Art looks different than it does for most kids. He was diagnosed with an extremely rare mitochondrial disease, thymidine kinase 2 deficiency (TK2d), when he was 17 months old.

Art Sr., Art Jr., and Olga Estopinan

Doctors told Art's parents, Art Sr. and Olga, that there wasn't much hope. They predicted he would only live for another couple of years.

But thanks to a then experimental treatment, Art is alive and thriving. Although he still needs around-the-clock care, he drives a power wheelchair and can breathe on his own.

The Estopinans credit their son's survival to Kygevvi (doxecitine and doxribtimine), the first and only treatment for people with TK2d that received FDA approval in late 2025 for children and adults who first show symptoms before age 12.

"I'm really lucky to have access to this drug," says Art, who one day hopes to become a doctor. "It allows me to go to school, see my friends, and play with my dogs."

Art's parents also credit their son's can-do attitude for his successes.

"He's so determined," says Olga. "He recognizes his limitations, but he's always willing and able to try."

Now that Kygevvi is available, more and more kids like Art will have access to the medication to help them lead longer, more fulfilling lives. That's why getting a prompt diagnosis is so important, stresses Olga.

"The sooner you can start treatment, the greater your chances to reverse the condition," she says. "We were lucky that we were able to get treatment for Art so early."

Challenges of Diagnosis

Art had a healthy birth and met all his developmental milestones during his first year of life. Then, around 14 months, his parents began to notice muscle weakness.

"First, he stopped standing up in his crib in the morning, and then he stopped crawling," Olga recalls. "I took him to a baby play group, and he folded his legs and cried because he couldn't do more."

Their pediatrician referred the family to a neurologist, who was worried enough to recommend hospitalization to more quickly run blood and muscle tests. When those came back abnormal, the medical team moved quickly to genetic testing.

While a diagnosis came fairly quickly, treatment was another matter.

"I called researchers everywhere – from Harvard in the East to Stamford in the West – to try to find a specialist who knew about experimental treatments," recalls Art Sr.

Finally, he landed on Michio Hirano, MD, a neurologist at Columbia University Irving Medical Center in New York.

"I almost fell off my chair when he told me his team was about to start a clinical trial for a new drug," says Art Sr. "For the first time since my son's diagnosis, I felt some hope."

There was one catch: The clinical trial for the drug was in mice, not in humans. But Hirano mentioned that Art Jr. might be eligible to try it, as part of a compassionate use program.

Art Sr. and Olga jumped at the chance. Their son was declining rapidly. He was so weak, he could barely move his arms and legs. They had recently taken him to the National Institutes of Health, where doctors warned he would soon need a ventilator.

The next week, the family drove to New York City from their home in Arlington, Virginia. Art was sick with a bad cold, and he worsened on the drive. "Olga wanted to turn around and take him back to our local hospital, but I said no," Art Sr. recalls. As soon as they arrived at Columbia, Art was admitted to the pediatric intensive care unit, where he was placed on both a feeding and breathing tube.

Trying New Therapies

Hirano recommended Art try the experimental medication that would soon be Kygevvi. He requested that it be given through the FDA's expanded access program. First, the drug company had to agree, then the FDA. A couple of months later, Art began the drug.

At that point, Art had been transferred closer to home, to Johns Hopkins. The family moved to Baltimore from Virginia to be closer to him.

If your baby or toddler has muscle weakness, seek out answers, even if your pediatrician tells you it's nothing

Olga Estopinan

"He was so weak that when we started the drug, in November 2012, we called in a priest to give him his last rites," recalls Art Sr.

"When he first began the drug, he was dead weight," Olga recalls. "The only muscles he could move were his eyes."

Change was so slow, and so subtle, Art's parents often didn't notice it until someone pointed it out.

"My mother would come to visit every three to four months, and she could really see the difference," Olga says.

When Art was discharged to go home, he returned to a nursery set up like a hospital ICU.

"Doctors warned us he was very frail, and there were no guarantees," Olga recalls. The toddler was on a ventilator and feeding tube, and required six respiratory treatments a day.

"There were alarms set all over the place to alert us whenever anything was off," says Olga.

But over the years, Art gradually regained some of his strength. While he still uses a ventilator at night, he doesn't need one at school. He's able to use his power wheelchair himself, and play adaptive basketball and soccer with friends at school.

"The fact that he can now raise his hand to ask a question at school, or type in something unassisted on his iPhone, is truly amazing," says Olga. "I never imagined we would be able to get to this point."

Life Today With TK2d

When Art was younger, he was too weak to go to school. At the age of 10, he started at a local Christian private school, where he is now in sixth grade.

"He was so sheltered at home, we felt he wasn't emotionally or socially ready yet to be with kids his own age," explains Olga.

Art attends school three days a week with a private nurse, and Olga goes with him two days a week. While he needs accommodations to help him speak and write, "his brain works perfectly well," points out Olga.

"Art has really thrived in school, because he loves to learn new things and meet new people. He's very social and well adjusted." While weak facial muscles still make it hard to talk, most of his teachers and classmates understand him now.

"When they don't, he'll type it for them," says Olga.

Still, there are challenges. Art wears a mask at school during cold and flu season, because even a mild virus can put him in the hospital. Olga also must give him respiratory treatments several times a day, where she suctions out his nose and uses a special vest to remove mucus from his throat and chest.

"We went on a family beach vacation this summer, and we ended up bringing about a third of the house," she laughs.

But Olga encourages every parent out there to listen to their instincts. "If your baby or toddler has muscle weakness, seek out answers, even if your pediatrician tells you it's nothing," she says. "Our pediatrician did that initially, but my instincts told me something serious was going on. You need to be persistent, and keep pushing for answers. Parents should always follow their intuition about their children."

Today, both Art and his parents have high hopes for his future. "There was a long time where I didn't even dare think about college," Olga admits. "Today, we have a 529 plan set up for him so that he can go. We are preparing him to be independent so that he can make his own financial and medical decisions."

It's uncharted territory, she adds. "He's the first child we know of to survive with this diagnosis at such a young age," says Olga. "He's writing the books as he goes along, so to speak. Our job is to get him ready for his future."

Posted : 2026-02-24 10:24

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