Parents Emily and Angus Forrester are in a ‘race against time’ to save their two-year-old daughter’s life, after she was diagnosed with a rare childhood dementia that will one day strip her ability to walk and talk
09:21, 23 Mar 2026Updated 11:41, 23 Mar 2026
A test gave the parents the all clear – but it was wrong(Image: STEVE FINN PHOTOGRAPHY)
Two-year-old Leni Forrester is “sunshine” personified – a joyful toddler obsessed with her dollies and singing Wheels on the Bus as she charges around in her toy car. To anyone meeting her, she is “just divine,” a little girl whose infectious laugh fills every room.
But beneath that joyful smile, a clock is ticking. Leni has Sanfilippo Syndrome, a rare genetic condition often described as childhood dementia. It is a heartbreaking disorder that slowly robs the child of the ability to walk, talk, and eat, with a severely reduced life expectancy.
For parents Emily, 33, and Gus, 35, the diagnosis was a bolt from the blue, with the couple having no clue that anything out of the ordinary. They had no concerns about Leni’s development until a routine genetic screening for Emily’s sister flagged a rare gene. Even then, a private medical test gave the family the “all-clear,” leading them to believe Leni was safe and encouraging them to try for a second child.
“We didn’t have any concerns at all about Leni,” her mum Emily tells the Mirror, explaining that everyone who meets the toddler who is “always laughing” is quickly struck by what an “exceptionally happy little girl” she is.
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Leni was diagnosed five months ago(Image: ITV)
Leni was diagnosed after her aunt flagged that she was a carrier(Image: ITV)
Emily and Gus, of Sevenoaks, Kent, have been together for 13 years, meeting back in their university days, and when they welcomed Leni, they had no idea that just 15 months into their daughter’s life they would receive some life-altering news. Emily’s sister was flagged as a carrier for the NAGLU gene – and there was a 50 percent chance Emily was too.
The odds that their child would be affected were still incredibly low – Gus would have to be a carrier too – but the couple decided “as a precaution” to get tested. Whilst Leni wasn’t showing many signs, when they looked up the symptoms of the disorder, Emily remembers saying to Gus: “God, I think she has this actually.”
“But because of how this syndrome progresses, they don’t really have any obvious symptoms that are different to what a normal toddler might experience before they’re two years old,” she explains, so the signs present were “nothing that you would piece together as this catastrophic genetic condition.”
Some of these included things that seemed to have a much more common or obvious explanation, for instance Leni’s bushy eyebrows, about which Emily says “both me and my husband have bushy eyebrows, so it’s not that unusual.” Other “subtle” facial features that can be symptomatic of the disorder can also be seen in Leni’s adorable face, like “thick eyelashes, full lips” but they are not particularly pronounced. Equally, Leni was born with talipase at birth, which saw her feet turned inwards, but physiotherapy managed to correct the issue.
Tragically, it is only when the children who suffer from the disorder start to lose all motor function that a genetic investigation usually takes place(Image: STEVE FINN PHOTOGRAPHY)
The couple were initially wrongly given the all-clear(Image: STEVE FINN PHOTOGRAPHY)
Altogether, if Emily’s sister had never mentioned it, there is little chance Leni would have been diagnosed for many years to come.
In fact, Emily explains, it’s often only when Sanfilippo has progressed incredibly far that children are ever diagnosed with it, because the first set of symptoms, which sees youngsters regress and lose their cognitive skills, “often mimics autism or ADHD as kind of a neurodivergence,” which can lead to misdiagnosis. Tragically, it is only when the children who suffer from the disorder start to lose all motor function that a genetic investigation usually takes place.
Because they were trying for another baby, Emily and Gus visited their doctor, but both her GP and the paediatrician Leni was referred to thought it was “incredibly unlikely” that Leni would have this condition. However, to be safe, they were referred on to a series of specialists, including a geneticist.
But there was a long journey ahead of them. It was two months before they could meet with the genetic specialist, followed by an agonising 12 weeks for the results. Amid all this uncertainty they stopped trying for a baby, and took matters into their own hands, booking Gus in for a private test.
The results came back all clear, leaving them elated. Emily said: “We were like, ‘Great, amazing, whatever is going on, worst case scenario is not possible because you’re not a carrier.'”
Children with the syndrome frequently appear healthy in early childhood(Image: STEVE FINN PHOTOGRAPHY)
After receiving all-clear, the couple started trying for a baby again. However, fate was about to deal them with another massive blow. Gus’s test had came back as negative, but it was incorrect.
Emily added: “He is a carrier, but for what they call a variant of unknown significance which means that never before in the global database has the gene that he carries been known to cause a child affected with Sanfilippo. So he just carries a very, very rare variant. So it wasn’t logged, which is why the private test came back as negative.”
At the NHS appointment with the geneticist, the couple decided not to mention that they had the private test giving them the all-clear, in order to not “skew their assessment.’
But the specialist’s concerns were quickly palpable. “Both us left that appointment and just had this sinking feeling in our stomachs that the geneticist clearly felt that something was at play, we could tell from how he was analysing her and the questions he was asking, it just felt like something really bad was going on,” Emily said.
The next day, he rang and told them he had put a rush on Leni’s test results, intensifying their anxiety. On the final day of their holiday, they received a call asking them to urgently get in touch with their doctor.
When they got home they received the devastating news, they were both carriers. Just a week before Leni’s second birthday, it was confirmed she has Sanfilippo.
Just two weeks later, they discovered Emily was pregnant. With a 25 percent chance their future child could be affected by the disorder, she had to endure an awful waiting game, with screening not available until three months.
Emily said: “Unfortunately the baby was also diagnosed with Sanfilippo so we felt we had no choice but to terminate the pregnancy.”
Explaining her daughter’s condition, Emily says, that Leni “has a fault in a single gene that produces a specific enzyme. That enzyme is responsible for breaking down a sugar molecule in her body called heparan sulphate. Essentially that sugar molecule is toxic waste and without it being broken down it builds up on various organs, but most importantly on the brain and causes irreversible brain damage.”
Emily and Gus are fighting for a future cure(Image: ITV)
Symptoms don’t show for some time because it is an “incremental build up” Emily explains, “which is why most children don’t get diagnosed till they’re kind of seven, eight years old,” when they begin to lose vital motor skills. Eventually, when it gets to that stage, Leni “will lose the ability to walk, to eat by mouth, any kind of motor skills, so it causes complete loss of all cognitive and motor function. It’s rapidly neurodegenerative so it’ll be over a quite short space of time and there is a life expectancy of early to mid-teens.”
Initially, Leni’s parents told there was “no treatment, no cure” for the condition, and essentially told to take their daughter home, and that they would be provided with palliative care, “which is obviously horrific”.
However, the determined parents – Gus is ex-military and now works for Lloyds of London Insurance Marketplace, and Emily is in marketing – started embarking on their own research. They found there are two potentially life-saving experimental treatments out there for their daughter, but they don’t come cheap.
The first ran a successful clinical trial at Great Ormond Street for several years, and saw the symptoms completely stopped in the participating youngsters with a weekly enzyme replacement therapy, delivered through a port in their brains. The second sounds even more promising: a gene replacement therapy that in similar conditions has been hailed as a total cure.
The first trial ran out of funding in 2017, Emily explains, which means all the children who took part “have now declined because they’re not receiving treatment or have died.” At the centre of this is profitability: with such rare conditions, there is not much money to be made by pharmaceutical companies – but the life of a child is priceless, no matter how uncommon their condition.
There is currently no cure available in the UK(Image: STEVE FINN PHOTOGRAPHY)
Emily and Gus are now fiercely fundraising to try and help get a life-saving treatment for Leni before it is too late, but they’re in a “race against time” because for either of the possible treatments to be effective, they have to get them to their daughter before she shows signs of regression, and loses the skills she has gained so far in her short life.
It’s a frustrating and torturous position to be in, Emily explains. “The medicine’s there, it’s already been produced. It’s just sat on the shelf,” but to access it is an uphill battle. The gene replacement trial will cost £5.5 million and could help six children.
Now Emily and Gus are trying to help fundraise to cover the “pre-clinical costs to get it to trial” because bringing the process forward even a few weeks could be life-changing for Leni. “When it’s your child’s life, how can you possibly put a price on this?” Emily says.
Earlier this month, Emily and Leni met with popstar Jesy Nelson. The former Little Mix star invited the pair to a Mother’s Day photoshoot to help raise awareness of rare conditions, after going through her own heartbreak with her twins, who have been diagnosed with SMA1.
“She’s trying to pull everyone along with her and like shine a spotlight on the difficulties that everyone faces,” Emily says about the singer. “So she’s super inspirational but also just a really genuine, lovely person.”
Emily and Leni met with Jesy Nelson recently
Meeting with other families in a similar position was invaluable to Emily, as she goes through the isolating process of fighting for her daughter. “Leni loved it,” Emily adds. “She’s such a little diva. She absolutely loved the cameras. It was a great day.”
Jesy is also full of praise for Emily and the adorable Leni, telling the Mirror: “Meeting Leni and her mum, Emily, really stayed with me. Leni is such a beautiful, happy little girl, and you can just feel how loved she is. Spending time with them was incredibly emotional, because it’s so hard to understand how something like this can happen to such a young child.
“Emily is amazing so strong and so devoted but no parent should have to fight this hard just to get their child the treatment they need. It’s heartbreaking.
“If sharing Leni’s story can help raise awareness or make even the smallest difference, then it’s so important we all come together and support them. Children like Leni deserve every chance at life. I’m sending all my love to Leni and her family.”
Being a member of “a club that no one wants to be in,” isn’t easy, and comes with unique challenges. What Emily and Gus imagined for their life feels distant, and potentially impossible. “When we got the diagnosis, I was like, that’s it, our lives are over,” Emily tells us. “Everything that we imagined our life was going to be. It is not that anymore.”
Currently, Leni has up to four medical appointments a week, prompting Emily to cut down to working three days a week. “It impacts every aspect of your life,” admits the mum.
But beyond the practicalities, the future they imagined has been robbed from them. “Everything that we have envisaged like Gus walking her down the aisle, having grandchildren, her going out late at night and sneaking back in, all of these things that you envisage for your life together and your family – it’s not just the child that is impacted by that, it’s everyone.”
Currently Leni struggles with hyperactivity and extreme insomnia; some children with Sanfilippo go days without sleeping, meaning it is difficult for others to care for Leni.
“We want to spend as much time with her as possible while she is still like she is now,” Emily says, “Any time away from her is emotionally difficult. You know you need the time away, but at the same time I don’t want to, because she’s so precious as she is now.”
The pair stay strong by fighting for their daughter, Emily tells us. “That is our coping mechanism, to be honest. We will just do whatever it takes now to get her access for this treatment.”
After much consideration, they have restarted their journey to grow their family, but it has not been easy. They could have “rolled the dice” and taken their chances that another baby would not be affected by the condition, but it was not worth the risk for them.
The process of genetic testing and IVF through the NHS is a long one, and could see them only able to attempt implantation in a year or 18 months from now. But Emily’s termination was only in December, and as someone who has suffered morning sickness so “horrific” that she had to be medicated, and endured a harrowing and painful test for Sanfilippo at the three month mark – she explains she “just can’t mentally go through that again”.
But they are “desperate” for Leni to “know her siblings and for her siblings to know her. We just want to grow our family and we want to have Leni have siblings that she can grow up around and that she knows before kind of any regression sets in.”
A Department of Health and Social Care spokesperson said: “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.”
Donate to Leni’s GoFundMe and help save her life at this link, you can also follow the family’s journey on TikTok here