(NewsNation) — A 19-month-old is the first person in the United Kingdom to receive a life-saving gene treatment, which is one of the most expensive drugs in the world, for her metachromatic leukodystrophy.

Teddi, the 19-month-old, and her sister Nala, 3, were both diagnosed with the disease, known as MLD, in April last year, according to a release from England’s National Health Service. The news release states that this genetic disease, which causes “severe” damage to the nervous system and organs, gives those who have it a life expectancy of between five and eight years.

MLD typically develops in children less than 30 months of age, according to the NHS, and potentially leads to the child losing their sight, speech and hearing. They may also have difficulty moving, brain impairment and even seizures.

The life-saving gene therapy Teddi received is called Libmeldy. Manufactured by a pharmaceutical firm based in the United Kingdom, Libmeldy removes a child’s stem cells, and replaces the gene that causes MLD before re-injecting the treated cells back into the patient.

Libmeldy has a list price of £2.8 million, which is $3,361,604 in American dollars, according to Forbes’ currency exchange chart.

“We are extremely privileged that Teddi is the first child to receive this on the NHS and grateful that she has the opportunity to lead a long and hopefully normal life,” Teddi and Nala’s mother, Ally Shaw, 32, said in a statement.

However, the family does have to face the pain of knowing Nala could not also get Libmeldy. Clinical guidance requires the therapy to be administered before “irreversible damage” from the disease progresses too far.

“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,” Shaw said. “We can only hope that one day, a treatment becomes available for all stages of MLD, and we feel strongly that it should be added to the newborn screening test to save more families from having to go through this heartache.”

So far, Shaw said, Teddi is doing “absolutely brilliant.”

The baby girl is walking, running, “a chatterbox,” and shows no signs of MLD, her mother said. “She is an absolute character and has everyone around her laughing all the time.”

The treatment Teddi received is being administreed at just five European sites, including the Royal Manchester Children’s Hospital. Before Libmeldy, there were no approved treatment options available, Professor Simon Jones, a clinical director of NIHR Manchester Clinical Research Facility at RMCH said.

Teddi was the first person in the UK to get Libmeldy outside of a clinical trail. She was only 12 months old when the removal of stem cells started at the end of June. The transplant happened in August, and in October, Teddi was discharged home to Northumberland.

Professor Rob Wynn, director of Royal Manchester Children’s Hospital’s Pediatric Bone Marrow Transplant Program, said being able to offer the treatment to “transform Teddi’s life” has been an exciting experience for all involved.

“It is wonderful to be involved in this breakthrough moment and deliver a gene therapy which will transform outcomes for patients with MLD,” Wynn said.

It is estimated around four babies a year born in England will be diagnosed with the condition, according to the NHS.