The mum of a toddler diagnosed with childhood dementia has had to tragically terminate her pregnancy after discovering her unborn baby had the same condition.
Leni Forrester was born seemingly healthy, but a family member taking a genetic test when she was 18 months old found the family carried a recessive gene which can cause Sanfilippo Syndrome – a rare, fatal genetic disorder also known as childhood dementia.
While the chances of both her parents, Emily, 33, and Angus, 35, carrying the gene were slim, the family all got tested after researching the minor symptoms associated with affected children – several of which Leni had, including speech delay, hearing issues and bushy eyebrows.
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They paid privately for Angus to be tested for the gene, and it initially came back negative, so they felt safe resuming trying to conceive a second child – but later discovered the test result had been incorrect.
Leni was diagnosed with the condition and, just two weeks later, Emily discovered she was pregnant.
She has sadly since had to terminate the pregnancy after the baby also tested positive for Sanfilippo Syndrome, all while battling to save her daughter.
“With no treatment options, no cure, a catastrophic prognosis and poor quality of life – how could we knowingly bring another child into the world with Sanfilippo Syndrome?” Emily, who works in marketing and is based in London, told Need To Know.
“We made the impossible decision to end the pregnancy, and I had a surgical termination a few days before Christmas.
“It was the most heartbreaking and difficult decision we have ever had to make.
“But we knew deep down that there was no choice.”
Only a few months ago, the couple had never even heard of the rare condition, and now say their world has been “ripped apart” by it.
While there is no known cure or treatment, the family have found promising experimental enzyme replacement therapy and gene replacement therapies, and are desperately fundraising to get Leni and other children access to it.
They have started a fundraiser with a goal of £500,000, and it has already surpassed more than £360,000 and attracted widespread attention online.
Now, they are sharing their story to shine a light on Sanfilippo Syndrome, and their hopes for the future.
Leni was diagnosed in October 2025 following the genetic testing.
Emily said: “It was the worst phone call any parent can possibly imagine.
“Initially we felt total shock and disbelief – looking at our perfect, happy, beautiful little girl, it was impossible to comprehend that there was anything wrong with her at all, let alone something so catastrophic.
“Nothing can prepare you for receiving such devastating and traumatic news about your child.
“We were told that it is neurodegenerative, without any treatment or cure, and a short life-expectancy.
“Unless you have received a catastrophic diagnosis like this for your child you cannot imagine the heartbreak and the devastation we felt in this moment.
“I now truly know what it feels like for your heart to be ripped out of your chest.
“It is the most intense grief.”
The shock was magnified by them spending the past month believing their worries were unfounded, following Angus’ test results, but the NHS confirmed that their results were conclusive.
When Emily discovered she was pregnant, she had to carry the fetus for three months before they could undergo genetic testing in utero.
“We knew this pregnancy would either be the very best or very worst possible news.
“Navigating the heartbreak of Leni’s diagnosis and our new world as parents to a child with very complex medical needs, as well as facing all the challenges any parent faces of having a toddler and trying to give her the best life possible, I carried our baby for three months, living with the constant worry that the baby would also be affected.
“We tried to detach from the pregnancy and not get our hopes up – but as there was a 75% chance that the baby would be unaffected, we couldn’t help but cling onto that hope.
“We desperately want to grow our family and want our future children to know Leni as she is today, and for her to know them.”
Sadly, it was more devastating news for the family – the baby had tested positive.
Meanwhile after her diagnosis, Leni was immediately referred to specialists at Great Ormond Street Hospital, who have taken over her care, and have explained her condition in detail to her parents – which Emily describes as “earth-shattering”.
Sanfilippo Syndrome Type B (MPSIIIB) is an extremely rare, affecting one in 200,000, rapidly neurodegenerative and life-limiting genetic condition.
With no treatment or cure, Leni’s parents were told to give her the best possible life for the short time she would be with them.
Now, their focus is on the experimental therapy and their fundraising efforts.
Emily said: “With Leni’s condition, weeks and months matter as toxic waste builds up in her tiny body every single day and the damage cannot be reversed once it is done.
“Time is working against us.
“The difference between her getting access to this treatment now and in a year’s time could be the difference between a potentially near-normal life and a significantly shortened life with the most severe mental and physical disabilities you can imagine.
“It’s now or never for Leni.
“It is every parent’s worst nightmare to be told that their child is going to die, and that is the haunting reality we are faced with if Leni cannot get access to treatment and fast.
“This is her only hope.
“Sanfilippo Syndrome is relentless and leaves no part of the child untouched by this condition.
“Our beautiful child who we are watching develop into an incredible little person and getting a glimpse of who she might become, will lose the ability to walk, talk, sleep, laugh, eat by mouth, and eventually her life to this condition.
“I cannot imagine a more cruel, catastrophic condition with a worse impact on the child or the families and friends who love them.
“We will do anything we can to save our baby girl, and that starts with raising awareness and funds to get her access to life-saving treatment.
“But alongside this, we want to make sure we make the most of the time we have with Leni as she is – an active, happy two-year-old full of love and laughter.
“We want to celebrate her and do all the things she loves.
“Travel, go on adventures and make memories as a family that we can treasure for life.
“She is a bundle of energy and everyone that meets her agrees that she is pure sunshine.
“She is perfection.”
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