When Domenic Catrine was born, his heel swelled up from his vitamin K shot. His circumcision site wouldn't stop bleeding.
At the Children's Hospital of Philadelphia, Catrine was diagnosed as having hemophilia, a rare blood disorder that impairs clotting and can cause serious and even life-threatening bleeds.
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"I didn't know what hemophilia was," said Catrine's mother, Brianna Borden. "I didn't know how to manage it. I didn't know anything."
Borden said she felt completely overwhelmed.
To protect his head against brain bleeds, Catrine, now 21, had to wear a helmet from the time he was a toddler through elementary school. To help his blood clot, he received intravenous infusions multiple times a week.
Eventually, Catrine graduated to once-a-week infusions that he learned to administer himself at a summer camp for children with serious and chronic medical conditions. Catrine even earned a black belt in karate.
Still, letting Catrine leave his South Jersey hometown, Delanco, to attend Montclair State University in North Jersey in 2022 was "nerve-wracking," Borden said.
"I raised him to be able to talk about his own illness, take care of himself, but I was always there to basically run the show," Borden said.
Without his mother to monitor his weekly infusions, as a busy college student, Catrine said he "started pushing it, trying to go maybe two, three weeks without doing my medicine."
He had two severe bleeds early in college: one when he got bumped playing football outside his dorm and another from an ankle injury he sustained while playing basketball with friends.
But then Catrine found out he was a candidate at CHOP for gene therapy – a treatment that he credits with transforming his life.
What is hemophilia and how is it treated?
Hemophilia, which has no cure, has two main types that differ based on deficiencies of specific proteins needed to help the blood clot. Hemophilia A is three to four times more common than hemophilia B. Their severity is based on the level of protein deficiency.
Worldwide, only about 840,000 people are living with hemophilia. They're mostly men, who aregenetically more predisposed to the disorder than women.
But just because hemophilia is rare doesn't mean it is "less clinically impactful" than other chronic illnesses, said Dr. Ben Samelson-Jones, a hematologist who treated Catrine at CHOP.
"In hematology, we care for these patients, and we want to work on helping them live with their disease and mitigating the consequences of what they have, even if few people have it," Samelson-Jones said.
Repeated bleeds, which are often internal, can cause long-term damage to joints and other body functions. Brain bleeds can be fatal.
Hemophilia can be managed with infusions of blood clotting proteins, in response to bleeds or prophylactically to help prevent bleeds.
Gene therapy for hemophilia – a relatively new treatment that CHOP has been at the forefront of developing – can eliminate the need for regular infusions. It uses viral vectors – viruses that have been altered to remove their disease-causing potential – to replace a defective gene with a working gene needed to improve blood clotting.
"After you get the gene therapy, you inevitably make an immune response against it, so you can only really get it one time," Samelson-Jones said. "It's not like, if it doesn't work in 2025, you can say, 'OK. I'll see what happens, and maybe in a couple years, I'll try something new.'
"It's not brain surgery," Samelson-Jones added. "But it has a lot of moving pieces that have to all fit together, and if something's not working, you don't get a second chance for that patient."
Domenic Catrine FamilyProvided Image/Borden Family
Domenic Catrine (top left) poses with his family (left to right): Ella, Brianna and Regire.
'All our prayers were answered'
Catrine, who received gene therapy at CHOP in 2024, responded well to the treatment. He has gone from having severe hemophilia B to having mild hemophilia. That means Catrine is no longer at risk for spontaneous bleeds or bleeds from minor trauma.
He doesn't have to deal anymore with the hassle and discomfort of weekly infusions, made painful by scarring from repeated injections through the years.
Catrine said he is more physically active. He even – somewhat to the chagrin of his doctors – recently went jet-skiing and rode ATVs.
It has "really been a blessing, just to live my life more freely and not have the stress and worries about every bump and scrape being a bleed," Catrine said.
This "lifting of the mental toll of managing the hemophilia" is one of the benefits of gene therapy that's "hard to capture scientifically," Samelson-Jones said.
If Catrine had a major accident or needed to have surgery, he would have to be treated with clotting factor infusions again. But Catrine's clotting factor levels should stay in a healthy range for at least the next 5 to 10 years and maybe longer, Samelson-Jones said.
"It was just like all our prayers were answered," Borden said. "It's not a cure, but it's probably the next closest thing that you could hope for, for somebody who dealt with what (Catrine) has had to deal with."