A fundraising campaign launched by the parents of a girl with Sanfilippo syndrome helped move an experimental gene therapy into human trials, contributing to research that secured Food and Drug Administration approval in September. Their daughter, Eliza O’Neill, was the first patient treated in the 2016 trial. Now nearly 17, she attends school and communicates using picture cards and devices.
Eliza’s parents began noticing developmental difficulties around her third birthday. She initially received a diagnosis of pragmatic speech delay: She knew many words but did not use them in typical social interactions. In 2013, a colleague of her mother, Cara O’Neill, a pediatrician in Columbia, S.C., recommended tests to rule out metabolic disorders. Instead, the results revealed Sanfilippo syndrome.
The inherited condition involves a faulty gene that prevents the body from breaking down a molecule needed for normal cell function. Its accumulation causes serious complications. According to the Cure Sanfilippo Foundation, which the O’Neills established and still operate, affected children lose speech and mobility, experience seizures and generally do not survive beyond their teenage years. Learning how rapidly the disease could progress pushed Cara and her husband, Glenn, to act.
At Nationwide Children’s Hospital in Columbus, Ohio, researcher Haiyan Fu had been developing a gene therapy in mice since the late 1990s. It uses a modified virus to carry a functioning gene into cells. Fu saw potential for a cure if treatment began early, but funding shortages nearly forced her to stop in 2009. Families intervened with financial support. Eight patient foundations, including Ben’s Dream and a Cure for Kirby, ultimately helped sustain the work until it was ready for human testing.
To help pay for a clinical trial, Glenn contacted filmmaker Benjamin Von Wong, who created a video for the family over several days in 2014. That spring, the Saving Eliza campaign raised $1 million within weeks, setting GoFundMe’s record at the time, and subsequently reached $2 million. The donations helped finance the first human trial, which began in May 2016.
The research attracted industry interest, and Ultragenyx acquired the therapy’s rights in 2022. After further studies, the company submitted data for FDA review. The approved treatment, Fayuvi, is a one-time infusion. Ultragenyx CEO Emil Kakkis said treatment offers the greatest benefit when children are younger, before substantial brain damage has occurred. He said some children treated at around 6 months had done very well.
Ultragenyx priced Fayuvi at nearly $4 million, tying it for the second most expensive gene therapy ever, according to drug price research firm 46brooklyn. Kakkis said the company was committed to getting every patient treated regardless of price. Following the approval announcement, Fu heard from Cara and other families who had supported the research, including some whose children had died. Welcoming the decision, Fu also said, “It shouldn’t take this long.”
Eliza was 6 when she received the experimental therapy and had already lost her speech, which did not return. Yet she continues to participate in school and activities. During the summer of 2026, she swam and learned to float with a pool noodle. Glenn described pride in his daughter after a difficult journey, while recognizing how fortunate she had been to receive treatment.
