Researchers cure toddler of deadly metachromatic leukodystrophy (MLD) for first time in history

Story: 2023 C.E.  |  Last updated: April 28, 2026

A 19-month-old girl from Northumberland, England, became the first patient treated on the U.K.’s National Health Service to be cured of metachromatic leukodystrophy — a rare inherited condition that destroys the nervous system and typically kills children before the age of eight. Teddi Shaw received a single course of gene therapy and is now disease-free, walking, running, and showing no signs of the illness that once made her prognosis fatal.

At a glance

• Gene therapy cure: Teddi was treated with Libmeldy, a one-off intravenous infusion that inserts functional copies of a faulty gene into the patient’s own stem cells, correcting the underlying cause of MLD before irreversible damage sets in.
• NHS drug access: NHS England negotiated a significant discount from Libmeldy’s list price of £2.8 million — making it the world’s most expensive drug — so eligible patients could receive it as standard care at the Royal Manchester Children’s Hospital, one of just five sites in Europe offering the treatment.
• MLD survival rates: About five children are born with MLD each year in England. Those whose condition begins before 30 months typically deteriorate rapidly and die between the ages of five and eight — making early detection and treatment access critical.

What gene therapy actually does

MLD is caused by a mutation that prevents the body from producing a crucial enzyme, allowing toxic substances to build up in the brain, spine, and other organs. There is no way to stop the damage once it progresses beyond a certain point.

Libmeldy works by extracting stem cells from the patient’s own bone marrow or blood, correcting the faulty gene in a lab, and then returning those cells to the body. The corrected cells go on to produce the enzyme the body needs — effectively reprogramming the patient’s biology from the inside.

Teddi’s treatment took place in several stages between June and October 2022 C.E. at Royal Manchester Children’s Hospital. By early 2023 C.E., she was thriving. “She is walking, running, a chatterbox — absolutely no signs so far of MLD,” her mother, Ally Shaw, told The Guardian. “She is an absolute character and has everyone around her laughing all the time.”

Why this moment matters beyond one family

MLD is rare enough that many families have never heard of it — until a diagnosis arrives and turns everything upside down. For decades, parents of children with MLD had no meaningful treatment options. That has now changed.

Amanda Pritchard, chief executive of NHS England, called it “a huge moment of hope” for families facing a diagnosis that was once a death sentence. Children who would have lost all function and died young can now, with early detection, live normal lives.

The implications reach further than MLD alone. Gene therapies like Libmeldy represent a new category of medicine — treatments that don’t manage a disease but eliminate its root cause with a single intervention. As the science matures and costs fall, the same approach is being explored for dozens of other inherited conditions, including some forms of blindness, immune deficiency, and neuromuscular disease. Research published in the New England Journal of Medicine has documented early successes across several of these conditions, building the evidence base for this emerging field.

The heartbreak that still remains

The Shaw family’s story carries real grief alongside its joy. Teddi’s older sister, Nala, was also diagnosed with MLD — but her condition had already progressed too far for Libmeldy to help. The drug must be given before irreversible neurological damage occurs, and that window had closed for her.

Ally Shaw has spoken publicly about the painful duality of their situation: profound gratitude for Teddi’s survival, and profound sorrow for Nala. She has called for MLD to be added to the newborn screening program in the U.K., so that future families can catch the disease early enough for treatment to work — for every child, not just some.

It’s a reminder that a medical breakthrough and an incomplete system can exist at the same time. The therapy works. The question now is whether screening and access can be expanded quickly enough to reach every family that needs it. A 2023 C.E. analysis in the BMJ highlighted the gap between the availability of new gene therapies and the newborn screening infrastructure needed to make them universally effective.

A model for what comes next

The Royal Manchester Children’s Hospital, where Teddi was treated, is one of the world’s leading centers for pediatric bone marrow transplant and gene therapy. Prof. Rob Wynn, director of the hospital’s paediatric bone marrow transplant programme, described the moment as “wonderful” — not just for Teddi, but as a proof of concept for a new era of treatment.

What makes this milestone particularly significant is the combination of scientific achievement and healthcare access. Gene therapies have existed in clinical trials for years; what changed here is that a national health system negotiated a pathway to make one available to patients at scale. That negotiation — between NHS England and Orchard Therapeutics, the drug’s maker — could serve as a model for how other health systems approach the next generation of high-cost, high-impact treatments.

For now, roughly five children born each year in England with MLD have a chance they didn’t have before. And one little girl from Northumberland is running around, talking nonstop, and making everyone around her laugh — which is, by any measure, a very good start.

Broader investment in gene therapy delivery infrastructure, as outlined in recent research published in Nature Medicine, suggests the scientific and logistical groundwork is being laid for many more breakthroughs like this one.

Read more

For more on this story, see: The Guardian

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