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19-Month-Old Treated For Deadly Genetic Condition With World’s Most Expensive Drug

Teddi, aged 19 months, became the first child in the UK to receive the gene therapy Libmeldy to treat her metachromatic leukodystrophy.

Laura Simmons - Editor and Staff Writer

Laura Simmons

Laura Simmons - Editor and Staff Writer

Laura Simmons

Editor and Staff Writer

Laura is an editor and staff writer at IFLScience. She obtained her Master's in Experimental Neuroscience from Imperial College London.

Editor and Staff Writer

brain with dna strand

The treatment works by correcting a faulty gene, preventing fatal nerve damage. Image credit: Kateryna Kon/

A 19-month-old girl named Teddi born with a deadly genetic disease has been successfully treated with life-saving gene therapy. The treatment, called Libmeldy, had a list price of around $3.9 million when a deal was negotiated for it to be provided via the UK’s National Health Service (NHS), making it the most expensive drug in the world at the time. It remains the most expensive drug licensed for use in Europe.

Teddi was born with a condition called metachromatic leukodystrophy (MLD). The symptoms most commonly begin to show up before a child’s third birthday and can include sight loss, hearing loss, and difficulty moving. Gradually, brain function is impaired, and seizures can develop. Life expectancy for those with MLD is between just five and eight years.


MLD is caused by a recessively inherited mutation in one of the genes coding for the enzyme arylsulfatase A. The usual function of this enzyme is to break down compounds called sulfatides, which are essential for normal nervous system function – but if they’re allowed to build up, they can be toxic. In people with MLD, who have less arylsulfatase A, the sulfatides are not cleared effectively, and gradually destroy the protective myelin sheath around nerve cells.

Teddi and her three-year-old sister Nala were both diagnosed with MLD in April 2022. Very sadly, Nala’s condition had already progressed too far for treatment to be an option. 

“Being told our first daughter, Nala, wasn’t eligible for any treatment, would continue to lose all functions, and die extremely young was the most heart-breaking and hardest thing to come to terms with,” said the girls’ mother, Ally Shaw, in a statement. “However, amongst the pain, was hope for our younger daughter, Teddi. We were told that a new gene therapy treatment had, luckily, recently been made available on the NHS.”

The treatment works by harvesting stem cells from the patient, which are then transduced in the lab with a virus containing a functional copy of the faulty gene. The cells, now able to correctly produce the arylsulfatase A enzyme, are then re-injected into the patient’s body. Teddi received the treatment last year, and, according to her mother, is displaying “absolutely no signs so far of MLD.”


“She is an absolute character and has everyone around her laughing all the time.”

The Royal Manchester Children’s Hospital, where Teddi was treated, is one of only five centers in Europe currently able to deliver this life-saving therapy. Although it may be too soon to declare the treatment a “cure”, the signs are hopeful, with children who previously received the treatment during the clinical trial reporting positive outcomes

Libmeldy is not currently licensed in the US. The manufacturer, Orchard Therapeutics, recently reported that they expect a formal meeting with the Food and Drug Administration (FDA) to take place in early 2023. The current most expensive treatment licensed for use by the FDA is another gene therapy, Hemgenix. Controversy around the pricing of such treatments is rife, with many questioning the justification for price tags in the millions of dollars. 

It is a debate that is set to rage on, as the science underlying these breakthrough treatments continues to progress. Fortunately for Teddi, the deal negotiated by NHS England that allowed her to receive this therapy means there is hope for her to lead a long and happy life.


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  • myelin sheath,

  • neurological disease,

  • drug prices,

  • genetic diseases