From a young age, Angie could sense that her body worked differently than other people's. Growing up, she felt like she had far less energy than everyone around her, but didn't understand why. While other kids stayed after school for sports practice or worked part-time jobs without thinking twice, she often wondered why the most basic activities left her yearning for her bed.
“It felt like I was always running on fumes,” Angie says, now 29. “I was barely getting through the day, and I didn’t even know if I’d have the energy to do the same things tomorrow.”
Finally, after years of these mysterious symptoms, Angie would learn that she has thymidine kinase 2 deficiency (TK2d). It's an ultra-rare mitochondrial disease that can cause progressive muscle weakness and affect the ability to walk, eat, speak, and breathe independently. The course of the disease varies widely depending on when symptoms begin: Infantile-onset TK2d is often fatal within one to two years, childhood-onset disease typically progresses more slowly, and later-onset forms may allow patients to live for decades. At the time of her diagnosis, however, Angie had little understanding of what TK2d might mean for her future.
When she tries to explain what it's like living with TK2d, Angie reaches for an image that captures the constant strain on her body. “I read once that it feels like you’re running a house on two AA batteries,” she says. “That’s accurate — it's like you’re doing so much with one quarter of the energy and strength you should have.”
As her disease progressed, even the most basic tasks became exhausting for Angie. Walking could feel like moving with cement around her ankles, and even talking felt laborious. Breathing, an essential function most people take for granted, became something she was always aware of. “It’s not automatic anymore,” she says. “You realize how big a deal it is, when it’s difficult all the time.” That’s because TK2d progressively weakens the muscles needed to breathe, including the diaphragm, turning inhales and exhales into an ongoing struggle.
For years, Angie watched her independence slowly slip away, spending days in bed, counting the minutes until she could rest again, never knowing when — or even if — relief would come.
A long road to answers
Angie describes her path to a diagnosis as an “odyssey” — one that took several years and multiple specialists before she finally received answers. Her journey began with her primary care physician, who referred her to a liver specialist. From there, she was referred to a neurologist and, eventually, a geneticist.
Ultimately, genetic testing confirmed her diagnosis of TK2d, a critical step that must be taken to identify the disease.
Despite receiving the diagnosis, Angie says that she wasn’t told TK2d is progressive. She recalls being told she would live a relatively normal life, with little discussion of what worsening muscle weakness or breathing challenges might look like over time. “I didn’t even understand what I had,” she says. “I just thought, OK, I’m not as strong as other people.”
As the years passed, the disconnect between what she’d been told and what she was experiencing became impossible to ignore. She continued to get weaker: Walking across her college campus was exhausting. Even sitting upright during online classes required more energy than she could manage. Eventually, she stopped attending school entirely. “I used to be in bed literally 20 hours a day,” she says.
Waiting for help
As Angie’s symptoms progressed, she researched her condition, reading about other patients and emerging data. An opportunity to participate in a clinical trial arose — she would get access to a treatment option that might help address the underlying cause of her disease. For the first time in years, her condition stabilized.
That treatment is now widely available — it’s KYGEVVI® (doxecitine and doxribtimine) 2 g/2 g powder for oral solution, the first and only FDA-approved treatment for TK2d in adult and pediatric patients with an age of symptom onset on or before 12 years.
Since starting KYGEVVI, Angie says she now has hope for the future. “When I look back, I was so sad all the time,” she says. “I felt helpless. I felt hopeless.” Now, she’s more optimistic since a treatment is now available.
Expressing herself through creativity
Sewing is a creative outlet she has loved for years. Her recent creation involved recreating a vintage-inspired nightgown she had admired for nearly a decade. Her most joyful project, however, might be the one she made for her pup.
Angie’s 15-year-old rescue dog, Suzy, recently celebrated a quinceañera. To mark the occasion, Angie modified a sparkly dress with Velcro closures to accommodate Suzy’s arthritis, making it easier and more comfortable for her to wear.
For Angie, sewing is not just a hobby — it’s an important part of her story.
Raising awareness of TK2d and looking ahead
When asked what she most wants people to understand about TK2d, Angie doesn’t hesitate. “First, I want them to know that it exists,” she says. She says that many recognize the phrase “the mitochondria are the powerhouse of the cell” — one of the most memorable takeaways from high school biology class. But few people understand what happens when mitochondria don’t function properly, or how deeply that dysfunction can affect a person’s daily life. She hopes greater awareness of TK2d will lead to earlier diagnoses, more informed care, and fewer people feeling as lost as she once did.
Today, Angie continues to navigate the realities of living with a rare disease. She continues to use a wheelchair but is actively working to regain mobility through physical therapy, alongside treatment. “There’s still a lot of work to be done that goes beyond treatment – it’s not an overnight transformation,” Angie notes. However, she’s no longer measuring her days by how long she can stay out of bed. Instead, she measures them in finished projects, small celebrations, time with loved ones, and the quiet joy of feeling like herself again.
And when Angie looks back on the years before she found stability, one concern stands out above all others. “I didn’t want to make my mom sad. I didn’t want to pass away before her, because I know how much it hurts parents to lose a child,” Angie says. “Without treatment, I felt like I would’ve died a few years ago. I’m just happy that I’m still here and get to see my family.”
The information provided on this site isn’t intended as medical advice, and shouldn’t replace professional medical treatment. Consult your doctor with any serious health concerns.
Indication
KYGEVVI is a prescription medicine used for the treatment of thymidine kinase 2 deficiency (TK2d) in adults and children with a symptom onset on or before 12 years of age.
IMPORTANT SAFETY INFORMATION
KYGEVVI may cause serious side effects including elevated liver enzyme levels. Increased liver enzyme levels in your blood are common with KYGEVVI. Your healthcare provider will do blood tests to check your liver enzyme levels before starting treatment and during treatment with KYGEVVI. Tell your healthcare provider right away if you develop any signs or symptoms of liver problems, including loss of appetite, pain on the right side of your stomach area, dark or amber-colored urine, yellowing of your skin or the white part of your eyes, nausea and vomiting, or itching.
KYGEVVI may cause stomach and intestinal (gastrointestinal) problems. Diarrhea and vomiting are common with KYGEVVI, but may also be severe and lead to hospitalization. Tell your healthcare provider right away if you have diarrhea or vomiting during treatment with KYGEVVI that lasts longer than a few days.
The most common side effects of KYGEVVI include diarrhea, stomach area (abdominal) pain including pain in the upper stomach area, vomiting, and increased liver enzyme levels in your blood.
Your healthcare provider may change your dose, temporarily stop, or permanently stop treatment with KYGEVVI if you develop certain side effects.
Before taking or giving KYGEVVI, tell your healthcare provider about all of your medical conditions, including if you have or have had liver problems. In addition, tell your healthcare provider if you are pregnant or plan to become pregnant. It is not known if KYGEVVI will harm your unborn baby. Also, tell your healthcare provider if
you are breastfeeding or plan to breastfeed. It is not known if KYGEVVI passes into your breast milk. Talk to your healthcare provider about the best way to feed your baby if you take KYGEVVI. Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.
These are not all of the possible side effects of KYGEVVI. Call your doctor for medical advice about side effects. You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch or call 1-800-FDA-1088. You may also report side effects to UCB, Inc. at UCBCares® (1-844-599-CARE [2273]).
Please see additional information in the Patient Information Leaflet and full Prescribing Information.
