The U.S. Food and Drug Administration has approved a prescription vitamin used for decades, folinic acid, as the first treatment for a rare genetic disorder in certain adults and children. Folinic acid is the active form of folic acid and can be utilized by the body directly without requiring reduction.

This decision follows the previous Trump administration's promotion of folinic acid months ago as a potential therapy for a broader population of individuals with autism symptoms. FDA officials stated that their initial review broadly considered the drug for autism treatment before narrowing the approval to a smaller group of patients with cerebral folate deficiency, a condition that prevents the key vitamin folic acid from properly reaching the brain.

The FDA's approval on Tuesday applies to a rare genetic disease in specific adults and children. This action comes after claims from the previous administration sparked skepticism from some in the medical and research communities but generated enthusiasm among families, leading to a surge in prescriptions across the United States.

An FDA official told reporters on Monday that there was insufficient data to confirm the drug's effectiveness for broader autism cases but indicated the agency remains open to companies studying folinic acid's use in the autistic population. Also known as leucovorin calcium, this synthetic form of vitamin B9 has long been used to counter toxic side effects of chemotherapy. Only a few small studies have suggested its potential benefit as an off-label treatment for autistic children, with some families reporting improvements in speech and social skills for their nonverbal children.

An FDA official, speaking anonymously while discussing the decision, explained that the agency initially conducted a broad review of folinic acid for autism before limiting approval to patients with cerebral folate deficiency. This rare genetic mutation typically manifests in children under two years old and shares overlapping characteristics with autism, potentially causing severe developmental delays, seizures, poor muscle control, and other serious neurological complications.

Officials stated that the FDA found the "highest quality data" supporting expanded indication from folinic acid use in these patients. The approval will apply to both generic versions of the drug and GlaxoSmithKline's established brand Wellcovorin. During a teleconference, an FDA official explained, "That's where we saw the largest effect sizes. We narrowed the focus to this group because we felt it represented the strongest scientific basis with the greatest treatment effect, sufficient to overcome some limitations in the data sources."

The approval is based on a systematic review of published literature in the field, including patient case reports, rather than randomized controlled clinical trials. The same official acknowledged potential bias in systematic reviews but emphasized that the treatment effect was substantial enough to outweigh these concerns.

FDA officials added that they encourage current manufacturers to increase production to meet higher demand. Although GlaxoSmithKline originally marketed the drug from 1983 to 1997, the company stated in September that it does not plan to reintroduce or manufacture the product itself.

In a press release on Tuesday, Dr. Tracy Beth Hogue, acting director of the FDA's Center for Drug Evaluation and Research, stated that this approval demonstrates the agency's commitment to "quickly identifying effective treatments for ultra-rare diseases while maintaining the same evidence standards for approval."