Expanded use of the drug leucovorin (Wellcovorin) for adults and children with FOLR1 related cerebral folate transport deficiency has been greenlit by the US Food and Drug Administration (FDA).1This is the first FDA authorised treatment for the rare genetic condition.But the FDA’s decision, announced on 10 March, was equally surprising for what it did not approve the drug for.In September 2025, US President Donald Trump’s administration promoted leucovorin as potentially helpful for some autism related symptoms.2The FDA said at that time that it was taking action to make the treatment available “for autism symptoms,”3 claiming that cerebral folate deficiency was associated with the condition.But the FDA seems to have stepped back from that.Anonymous FDA officials quoted by CNN said that there was not “sufficient data” for the drug as an autism treatment and that “we don’t have the evidence now for a broader approval.”4The BMJ contacted the FDA for comment,…