The United States Food and Drug Administration has approved leucovorin, a longstanding synthetic folate supplement, as the first targeted therapy for cerebral folate deficiency—a rare genetic disorder that prevents this vital vitamin from reaching the brain, triggering severe seizures, developmental delays, muscle weakness, and traits overlapping with autism in young children under two.
Announced on Tuesday, the decision applies to both adults and children with the condition, which affects fewer than 200,000 Americans and demands urgent intervention to avert permanent harm, as outlined by the National Organisation for Rare Disorders.
Leucovorin, known medically as folinic acid and historically sold as Wellcovorin by GlaxoSmithKline until 1997, has long countered chemotherapy toxicity but showed promise in small studies for folate transport issues.
This milestone comes amid lingering controversy from the Trump administration’s push last year to position it as a broader autism remedy. While experts questioned the evidence base, desperate families embraced it, fuelling a prescription boom that sparked U.S. shortages, according to CNN reports.
Speaking anonymously on Monday, FDA officials explained narrowing their review from autism to this niche group after identifying robust data.
“That was the data where we saw the largest effect sizes,” one remarked. “So we narrowed in on that population, just because we felt like that was the strongest both scientific rationale and also the largest treatment effects that could be used to then overcome some of the limitations in the data sources.”
The approval rests on a synthesis of published research and patient cases rather than a large randomised trial, with officials stressing the outsized benefits outweighed methodological flaws. They also noted, “we don’t have sufficient data to say that we could establish efficacy for autism more broadly,” but invited pharmaceutical firms to pursue further studies.
GlaxoSmithKline backs the label expansion without plans to resume production, prompting the FDA to call on generics makers to ramp up output.
Dr Tracy Beth Hoeg, acting director of the FDA’s Center for Drug Evaluation and Research, praised the move as proof of the agency’s drive to “rapidly identifying effective treatments for ultra rare diseases while maintaining the same evidentiary standards for approval.” For afflicted families, it signals real hope through early testing and treatment.