Sanfilippo syndrome is a progressive, incurable neurodegenerative disease that causes children to gradually lose motor skills like walking, talking, and eating, typically leading to death by the mid-teens. There is currently no cure and no UK-approved treatment for Sanfilippo syndrome. Leni's parents, Emily and Gus Forrester, received her diagnosis in October 2025.
Leni's parents terminated a pregnancy after in utero testing revealed the fetus also had Sanfilippo syndrome, adding to their family's personal tragedy. Another family's experience illustrates the disease's devastating progression. Sophia Scott is a 15-year-old girl with Sanfilippo syndrome who can no longer speak and cannot walk unaided, and may not live past her 16th birthday.
Sophia's parents, Darren and Amanda Scott, were given a single sheet of paper and advised to make the most of their time with her after her diagnosis just before her fourth birthday. Celebrity involvement has helped raise awareness for rare conditions like Sanfilippo syndrome. Popstar Jesy Nelson met Leni and her mother Emily for a photoshoot to raise awareness for rare conditions.
Jesy Nelson has twins who were diagnosed with Spinal Muscular Atrophy (SMA), giving her personal insight into rare diseases. Potential treatment developments offer some hope amid the challenges. A clinical trial for a new treatment for Sanfilippo syndrome will begin in the US later this year.
Leni's parents are urging the UK government to fund research and clinical trials for Sanfilippo syndrome to help families facing this condition.