A toddler from Kent faces a desperate race against time for a life-saving treatment, with a crucial window of just six months before her third birthday to halt a devastating form of childhood dementia.
A Family’s Unexpected Battle
For Emily and Gus Forrester, the first hint of their daughter Leni’s condition came not from a symptom but from a relative’s routine genetic test. The test revealed a carrier gene for Sanfilippo syndrome, a rare and fatal neurodegenerative disorder. Doctors initially reassured the family it was highly unlikely Leni was affected, but the results prompted further investigation. One week before Leni’s second birthday, that investigation delivered a catastrophic diagnosis.
Sanfilippo syndrome is a genetic condition caused by a deficiency of a specific enzyme. This deficiency prevents the body from breaking down complex sugar molecules called glycosaminoglycans (GAGs), leading to their toxic accumulation in cells and catastrophic, progressive brain damage. Children typically develop normally until around age two or three, before suffering a relentless loss of memory, speech, and mobility, with most not surviving beyond their teenage years.
“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 Forrester said. “It is a race against time.”
The Treatment Horizon and a Funding Chasm
While there is no cure or approved treatment for Sanfilippo in the UK, promising avenues exist, all blocked by a critical lack of funding. One hope is a US clinical trial for an enzyme replacement therapy (ERT), expected to begin later this year. The treatment involves surgically fitting a permanent port in the brain to allow weekly infusions of the missing enzyme, a process needed for life. The cost to fund this trial stands at £5.5 million.
“For an individual, £5.5m is a huge amount. But for a nation, it is not,” Ms Forrester said.
This is not the first time a treatment has been within reach. Great Ormond Street Hospital in London previously ran a six-year clinical trial that reached final phases with effective results, only to be cut due to lack of funding. Children on the trial who had developed normally subsequently declined once the treatment stopped.
Alongside ERT, significant hope lies in gene therapy developed by UK-based researcher Professor Brian Bigger. His work includes OTL-201, an investigational gene therapy for Sanfilippo Type A developed with Orchard Therapeutics and Manchester University NHS Foundation Trust. A proof-of-concept study showed four out of five treated patients developing cognitive skills in line with healthy children. His team is also developing stem cell gene therapies for Sanfilippo Type B. However, Professor Bigger’s research cannot advance to clinical trials without significant investment.
A System Failing Families
The Forrester family’s campaign highlights systemic gaps in the UK’s approach to rare diseases. They are calling for the government to fund research and expand newborn screening to detect conditions like Sanfilippo earlier. The UK currently screens for just 10 rare diseases in its Newborn Blood Spot test, far fewer than many comparable countries.
Bob Stevens, CEO of the MPS Society, a charity supporting those with Sanfilippo and related diseases, said: “There is no scientific reason that we cannot screen for many of these diseases, but we know it comes down to money. For conditions like MPS III [Sanfilippo], early diagnosis is essential as new therapies move closer to reality.”
The family has expressed frustration at the difficulty of getting a response from senior politicians without a celebrity platform. They contrasted their experience with that of singer Jesy Nelson, who successfully met Health Secretary Wes Streeting to advocate for newborn screening for Spinal Muscular Atrophy (SMA), which affects her twin daughters.
“Politicians should prioritise meeting families suffering with the genetic disorders, not only celebrities to get their screen time,” Ms Forrester said. Mr Stevens said he was promised a meeting with the Health Secretary last summer that was not upheld, and the family’s local MP, Laura Trott, has also requested an unanswered meeting with Mr Streeting.
The government points to the UK Rare Diseases Framework, extended until 2027, which aims to speed up diagnosis and improve care. A Department of Health and Social Care spokesperson said: “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.”
However, for families, the disparity in attention and resource is stark. “These children have been pushed to the side,” Emily Forrester added. “There is no support for the families, even though the impact of childhood dementia is the same as childhood cancer; there is a huge difference in research and funding.”
With time running out, Leni’s parents have set up a GoFundMe page to raise funds for treatment, a stopgap measure for a problem they believe the state must ultimately solve. The case underscores a urgent choice: invest in cutting-edge science now or consign families to a future where treatments exist, but remain out of reach.