A nine-year-old girl traded her wheelchair for a walker after taking a drug made just for her, built from her own genetic code.
Quick Take
- Mayo Clinic is building custom gene therapies for patients with diseases so rare that no drug company will touch them.
- The approach, called N-of-1 medicine, designs a treatment around one patient’s exact genetic mistake.
- A young Mayo patient showed real gains in movement and speech after starting her experimental drug.
- The method follows a path blazed by a 2018 case known as milasen, now backed by new federal guidance.
Mayo’s Search For Patients Medicine Has Forgotten
Mayo Clinic runs an active study called Individualized Therapeutics in Rare Genetic Disease, built to find patients whose rare genetic disorders might respond to a custom-made drug called an antisense oligonucleotide. Researchers study the patient’s exact genetic flaw, then design a molecule to correct it. The goal is to move from lab bench to an actual treatment given to that one patient in what’s called an N-of-1 clinical trial.
Doctor Erica Cousin leads Mayo’s N-of-1 Therapeutics Program, where scientists build treatment strategies for patients who have run out of other options. These are not diseases with support groups or awareness ribbons. Many affect a single known patient on Earth. Mayo’s bet is that building treatments this way, one person at a time, can still teach doctors lessons that help far more people down the road.
A Nine-Year-Old’s Steps Show What’s Possible
Maggie Carmichael became one of the clearest signs of progress. Months after starting her experimental drug for an ultra-rare genetic disease, the Mayo Clinic patient swapped her wheelchair for a walker. She took her first unassisted steps. Her feeding skills improved, and so did her speech, according to Mayo Clinic’s own reporting on her case. Stories like hers are rare, but they are real, and they show these custom drugs can change daily life.
Mayo is not working alone in this space. The clinic runs a broader study to better understand the biology behind rare and genetic diseases, tracking symptoms, disease progression and biological markers that could point toward future treatments. Its Center for Individualized Medicine has spent more than a decade building precision diagnostics based on each patient’s unique genetic makeup, giving doctors a running start when a new rare case arrives.
The Milasen Blueprint Behind Today’s Custom Drugs
This approach did not start at Mayo. In 2018, researchers at Boston Children’s Hospital built a drug called milasen for a girl named Mila Makovu, whose rare mutation caused seizures tied to a form of Batten disease. Doctors went from diagnosis to treatment in about ten months, and Mila’s seizures grew less frequent afterward. Her case proved the model could work, even though it did not undo all the damage already done to her nervous system.
That breakthrough pushed federal regulators to build a real path for this kind of medicine. The Food and Drug Administration (FDA) issued draft guidance creating a framework to speed up development of individualized therapies for ultra-rare diseases, letting sponsors show a drug works through a plausible biological mechanism when standard large-scale trials are simply impossible with so few patients. A 2025 review found at least 28 patients worldwide had received a mutation-specific antisense drug between 2018 and 2024, a small number but a sign the field is growing.
Why This Model Matters For Families With No Other Options
Families facing an ultra-rare diagnosis have long heard the same grim line: too few patients exist to justify a drug company’s investment. Mayo’s model flips that math. Instead of waiting for a large enough patient population, researchers build the therapy around the one patient in front of them, then study what they learn for the next family that walks through the door.
This is not a cure-all, and it will not work for every rare disease or every patient. But it represents medicine choosing to act on behalf of people the market had written off. For conservative-minded readers who value personal responsibility paired with real innovation, this is exactly the kind of result-driven, patient-first research that deserves support, not bureaucratic delay.
Mayo Clinic’s work also strengthens the case for pairing fast genetic diagnosis with rapid drug design in children’s hospitals. The clinic’s BabyFORce program already combines whole-genome sequencing with artificial intelligence to speed up diagnosis in newborns with serious or rare diseases, cutting the time families spend searching for answers. As that diagnostic speed meets Mayo’s N-of-1 treatment pipeline, more children may get a shot at a drug built just for them, before their disease does lasting damage.
Sources:
youtube.com, mayo.edu, newsnetwork.mayoclinic.org, mayoclinic.org, nature.com
