Living Life with PBD-ZSD

Thomas, when he was a little boy, talks about his family, favorite activities and shares a knock-knock joke.

Thomas enjoys many things typical of twelve-year-old kids: sports, time with his friends, and playing video games.

But Thomas’ journey has not always followed the typical path for kids his age. Thomas balances activities like cross country and basketball with managing a rare condition called peroxisome biogenesis disorder-Zellweger spectrum disorder (PBD-ZSD).

Thomas’ path to diagnosis was not straightforward. His symptoms first began appearing when he was 18 months old. His parents Kim and Brent noticed he was experiencing loss of vision and hearing.

With this information in hand, doctors informed them that Thomas most likely had Usher syndrome: a rare genetic disorder characterized by vision and hearing loss. In order to confirm the diagnosis, Thomas’ parents immediately moved forward with genetic testing and were told that the process would take nine to 12 months.

“After nine months, I started calling the lab every day, just to see,” said Kim. Eventually, it was communicated that the blood sample had been misplaced.

Armed with that news, Thomas’ parents did new genetic testing on themselves and Thomas. Those results came back negative for the 42 most common types of Usher syndrome. Yet, doctors were still convinced it was a genetic mutation for the disorder that just had not been identified yet. As a result, the family continued to search.

I’m a speech therapist with a healthcare background, so I wanted to make sure we were finding the right diagnosis and didn’t need to look at other systems in his body,” Kim recalled. “I just kept pushing for someone to know what we should test for.

Thomas was six years old before doctors correctly identified his condition through a larger gene panel that tested for other rare disorders. Within a few months of sending along one of Thomas’ blood samples, geneticists found a match for PBD-ZSD, a metabolic disorder.

PBD-ZSD, often shortened to Zellweger, is a rare condition characterized by alterations in one of the body’s PEX genes, which leads to loss of peroxisome function. Peroxisomes are necessary parts of a cell that help to break down fats, chemicals and cellular waste.

Without functioning peroxisomes, people with PBD-ZSD may experience multisystem complications, including neurological problems and seizures, delayed growth and development, hearing and vision loss, poor muscle tone, and skeletal and dental abnormalities.

There are no treatments to halt the progression of PBD-ZSD, but treatments exist to address key effects of the disorder.

I‘m a little less scared about high school now. I’ve learned a lot this year about Thomas’ ability to thrive.

-Kim, talking about her son Thomas on his near-term transition to high school.

Managing Junior High School

“At this stage at the junior high, he’s kind of on his own – just like a regular kid. I don’t even know who the school nurse is, which is crazy,” Kim said. “I’m a little less scared about high school now. I’ve learned a lot this year about Thomas’ ability to thrive.”

Thomas is now in junior high school and in regular classes alongside his friends. His condition has gotten easier to manage over the years. Kim praises him for how independent he’s become.

However, some things have become more difficult with age.

“Right now, we’re coming onto the teenage years, and he doesn’t want to be different,” Kim said.

For his parents, their main priorities center around keeping Thomas mentally and emotionally healthy and preparing him for his future – especially as it relates to his vision.

Because of his vision loss, certain coming-of-age activities like driving will never be possible, and it prevents him from participating in some of the same sports that his friends are playing. Thomas also has to stand rather close to people in order to recognize their faces, sometimes making others uncomfortable.

For this reason, attending junior high school during the pandemic in a remote environment has been a bit of an equalizer for Thomas in certain respects, according to Kim. Online school has meant the technology Thomas uses to digitally magnify his schoolwork isn’t particularly apparent to his classmates who are all also using tablets and laptops to learn.


Lessons in Family Support and Openness

One thing that Kim and Brent have tried teaching Thomas is how to be open with others about his condition – including his doctors, friends and family. With the topic being rather sensitive, however, this hasn’t always been easy for Thomas to navigate.

For a time, Thomas was experiencing anger issues, often feeling out of control and anxious. Together, they drew a diagram that included PBD-ZSD in the middle, with different offshoots listing the things that Thomas struggled with because of his disorder. This helped Thomas understand the root cause of some of his more challenging day-to-day experiences.

“Now we do check-ins, asking ‘how are you doing with Zellweger? How is Zellweger affecting your life today?’” Kim said.

It helps that the family is very supportive and involved in each other’s lives. Thomas and his younger brother Gage are very close – both in age and emotionally.

“Trying to keep the boys’ lives even-keeled and happy is what keeps Brent and I going.”

When Thomas was receiving his first liver biopsy, Kim scheduled the appointment during the school day so that Gage would be in class. But that afternoon, Gage wouldn’t stop crying.

“He was finally able to articulate that he wanted to be there for Thomas. He didn’t like that he had to be at school when his brother needed him,” Kim said.

Now, Gage doesn’t always attend Thomas’ appointments, but his parents always make a point of asking if he would like to accompany Thomas to show his extra support. This is yet another aspect of parenting a child with a rare disease that Kim and Brent have learned to manage: being there for both kids in different ways, all while trying to limit as many stressors as possible.


The PBD-ZSD patient and caregiver community has also been a point of support and education for the family, but their involvement comes with its own set of pain points.

“I feel like we’re the lucky ones, because Thomas is doing so well. There’s such mixed feelings, where I feel guilty around other parents who are really struggling or have lost their kids.”

But Kim still makes sure to respond to posts and comments on the Zellweger Syndrome Support Facebook page, helping answer questions and offering her own experiences to other families within the community.

Since Thomas’ diagnosis, the family has also focused on raising money for research. They started organizing a fundraiser for the Global Foundation for Peroxisomal Disorders called Trekking for Thomas: a kids’ fun run in their neighborhood that’s now approaching its fifth year. Kim attributes opening up her family’s closer-knit bubble and getting more involved in the community to this annual event.

“A lot of families join in, so that’s how the community really got to know what is going on.”

For more information on PBD-ZSD, please visit the Global Foundation for Peroxisomal Disorders.