FDA Approves Leucovorin for Cerebral Folate Deficiency

The Food and Drug Administration approved an expanded use for the drug leucovorin on Tuesday, allowing it to treat cerebral folate deficiency, a rare genetic condition that can cause neurological symptoms overlapping with those of autism spectrum disorder. This decision comes nearly six months after administration officials, including President Donald Trump and Health Secretary Robert F. Kennedy Jr., promoted the synthetic form of vitamin B9 as a potential treatment for autism itself, a claim the agency now says lacks sufficient supporting evidence.

Leucovorin, traditionally used to reduce side effects from chemotherapy, works by delivering folate to the brain when standard folic acid cannot cross the blood-brain barrier effectively. Cerebral folate deficiency, caused by variants in the folate receptor 1 gene, leads to low folate levels in the brain despite normal blood levels, resulting in issues such as seizures, intellectual disability, and challenges with speech, social interaction, and repetitive behaviors. The condition affects an estimated one in a million people, with only about 50 documented cases linked to this specific genetic form.