Before the diagnosis
Felix is four, and he has never been one to sit quietly on the sidelines.
He is endlessly curious, constantly asking questions, narrating whatever adventure he has invented, and insisting on doing things himself—even when doing it himself takes considerably longer. He is funny and mischievous, fiercely independent, and determined in a way that makes it very hard to tell him he can’t do something.
He is also an aspiring inventor. Give him a pile of random toys, household objects, or whatever is within reach, and with a little help from Pop Pop, he’ll find a way to turn them into something new. He is always building, experimenting, figuring out how things work, and coming up with his own solutions to problems that most four-year-olds haven’t even noticed yet.
He adores his big sister, Violet, and loves being part of whatever is happening around him. He notices everything, has very strong opinions about everything from breakfast to bedtime stories, and can make an entire room laugh without even trying.
For a four-year-old, Felix also feels things deeply. He is remarkably empathetic, quick to notice when someone else is hurting or needs comfort, and loves with his whole heart. There is truly no better love—or better hug—than one from Felix.
He is joyful, curious, stubborn, hilarious, endlessly imaginative, and completely himself.
Finding answers
Long before there was a name for it, his family knew something wasn’t quite right.
Felix had trouble with balance and coordination. He fell often. His gait was unusual, his ankles were unstable, and things that seemed effortless for other kids—jumping, navigating stairs, keeping his balance—required more concentration for him.
What followed was a long search for answers: appointments, specialists, tests, and a lot of waiting.
Eventually, genetic testing identified changes in a single gene: COX20.
Felix was diagnosed with COX20-related mitochondrial complex IV deficiency, an ultra-rare mitochondrial disorder. For his family, the diagnosis finally meant having a name for what they had been seeing all along—and, just as importantly, a place to begin looking for answers.
Living with COX20 deficiency
COX20 plays an important role in assembling mitochondrial complex IV, part of the machinery mitochondria use to produce energy for cells. When COX20 is not functioning properly, complex IV can be impaired.
For Felix, that has meant challenges with balance, coordination, gait, speech and articulation, and swallowing. It has meant falls, therapy, specialists, and more planning than most four-year-olds—or their families—ever have to think about.
But his diagnosis does not define him.
Felix is still the kid who wants to do everything himself. The kid who asks a million questions. The kid who invents things, loves to laugh, loves his sister, and throws himself into whatever comes next.
Our job is to help make sure his disease does not get the final say in what he is able to do.
Why gene therapy matters
COX20 deficiency is caused by changes in the COX20 gene. That makes gene therapy a particularly compelling area of research: the goal is to deliver a functional copy of the gene to cells, with the hope of restoring COX20 function and improving the underlying mitochondrial defect.
For Felix, that possibility changes everything.
It means we don’t have to simply watch and wait for a disease to progress when there is no approved treatment today.
It means we can help move the science forward.
Felix gave us a reason to start.
Mighty Mito exists to ensure that patients who come after him have more options than they have today—and to help turn promising science into treatments that can reach the patients who need them.