Gus and Emily Forrester’s world changed forever just five months ago when doctors diagnosed their vibrant two-year-old daughter, Leni, with Sanfilippo Syndrome Type B (MPSIIIB)—a rare, inherited, and devastating condition often referred to as “childhood dementia.” In an interview with ITV News published on March 23, 2026, the Forresters described the diagnosis as “every parent’s worst nightmare.”
Leni, a smiling toddler known for her boundless energy and love of learning, now faces a future shadowed by a progressive, terminal disease that has no FDA-approved treatment or cure. According to the Cure Sanfilippo Foundation, children with this syndrome typically begin showing signs of developmental delay between ages one and six. The disease, caused by an enzyme deficiency, leads to the accumulation of toxic molecules in the brain. As these molecules build up, they cause irreversible damage to brain cells—damage that usually begins around the age of three. Over time, children gradually lose their ability to talk, walk, eat, and drink.
"All your dreams for your child’s future are taken away," Emily told ITV News. "To be told that she has this condition, and there is no treatment and no cure and no support… it’s completely earth-shattering." The couple’s heartbreak is compounded by the knowledge that, without intervention, Leni will endure a relentless physical and mental decline, ultimately leading to death in her early to mid-teens. "If we can’t get treatment, she will suffer the most awful physical and mental decline you can imagine and then die in her early to mid-teens," Emily explained to ITV News.
Sanfilippo Syndrome’s cruel progression means that every new word, every milestone, is tinged with sadness. "Every day that passes without treatment, this toxic waste is building up in our child’s body," Emily said. The urgency is palpable: early treatment is critical, and even brief delays can have catastrophic consequences. "If she has to wait six months, that could mean she can no longer talk. If she waits 12 months, that could mean she loses the ability to walk," Emily emphasized. The damage, once done, cannot be reversed.
Despite the bleak prognosis, there is a glimmer of hope. A clinical trial for a potential treatment is expected to begin in the United States later this year. The Forresters are fervently appealing for UK government support to include British patients like Leni in the trial. "It’s extremely frustrating because the science is there. The data is there. It’s proven to be effective, and yet we cannot access it," Emily said. The family’s frustration is echoed by Professor Brian Bigger, a University of Edinburgh researcher who has developed a gene therapy approach targeting childhood dementia. His method delivers a missing gene into patients’ blood stem cells, offering a potential lifeline. However, launching clinical trials requires significant funding—a challenge that charities alone cannot meet. "Charities typically can’t fund this kind of thing," Professor Bigger told ITV News. "It would be really good if we could see more commitment from government towards these kinds of therapies. There are hundreds of kids like Leni out there who don’t have any therapy, and these treatments have the potential to be transformative." He added, "We’re racing against time. She will start to lose brain cells and when that happens we’re not going to get them back."
The Forresters have turned their anguish into action, launching a GoFundMe campaign that has already raised over $250,000 toward potential treatments and the costs of Leni’s care. They have pledged to donate some of the funds to Great Ormond Street Hospital, which is providing Leni with world-class care, and to the Cure Sanfilippo Foundation, which supports families facing this rare disease. In addition, they have set up an Instagram account to raise awareness of childhood dementia and connect with other families in similar circumstances. Their advocacy extends to campaigning for newborn screening programs that could help detect rare genetic conditions earlier, and for increased government funding for research and treatment development.
Emily’s frustration is palpable. "We shouldn’t have to fight for our child’s life," she said. "She is as valuable as any other child. But no one is fighting for her." Gus echoed her sentiments, underscoring the universal role of parents: "As parents, your role is to protect your children and provide every opportunity you can. Without any treatment, her future and her reality is very, very dark." He also pointed out that while Sanfilippo Syndrome is rare, rare diseases collectively affect many families. "When you group all these rare conditions together, they suddenly don’t become that rare. They affect a lot of people and a lot of families."
Childhood dementia, including Sanfilippo Syndrome, affects around 240 children born in the UK each year. Yet, as Professor Bigger noted, the issue remains largely overlooked. "All of us have a family member who’s been affected by dementia. Childhood dementia is no different. It’s just much, much worse—because it’s your kid." The Forresters’ campaign is not just about their daughter, but about the hundreds of children facing similar battles without access to effective therapies.
The UK Department of Health and Social Care responded to the family’s appeals with a statement to ITV News: "Our thoughts are with all those living with dementia and rare conditions including Sanfilippo syndrome. We are making sure patients with rare diseases, like Sanfilippo syndrome, get a definite diagnosis faster, while improving access to specialist care, treatment and drugs. At the same time we are working hard to find new ways to slow down the progress of the dementia, speed up diagnosis and improve our understanding of the disease." While the statement signals some official recognition, the Forresters and advocates like Professor Bigger believe much more is needed—especially government investment in clinical trials and newborn screening programs.
For now, the Forresters continue their race against time, buoyed by community support and their determination to give Leni every chance at life. Their story, while deeply personal, resonates far beyond their family—shining a light on the urgent need for more research, funding, and awareness for rare childhood diseases like Sanfilippo Syndrome. In their words and actions, they remind us that every child’s life is precious, and that hope, even in the darkest moments, is worth fighting for.