The FDA is approving a generic drug for a very rare genetic disorder, but not for autism. On Tuesday, the U.S. agency said the drug helps children and adults who cannot get enough folate into the brain. That’s a major turnaround from announcements made at a White House news conference in September. At that event, President Donald Trump and the FDA commissioner said the drug was under review for approval in patients with autism. FDA officials say they narrowed the review to the strongest evidence. They say that evidence only supports use in patients with a specific genetic mutation.