The US FDA has approved GSK's Wellcovorin (leucovorin calcium) as the first treatment for cerebral folate deficiency (CFD-FOLR1) in adult and pediatric patients with a confirmed pathogenic variant in the FOLR1 gene.[1][2][4] The approval is for a rare genetic neurological disorder that affects fewer than 1 in 1 million people in the US and is documented in 20 to 50 cases.[1][3] Patients suffer from severe developmental delays, movement disorders, seizures, and other neurological complications that may resemble autistic symptoms.[1][2][3] The FDA's decision was based on a systematic review of published literature, case reports, and mechanistic data, not clinical trials, due to the extreme rarity of the disease.[1][2][4] FDA Commissioner Marty Makary called the approval a significant milestone for patients without an approved treatment.[2] The approval was limited to CFD-FOLR1 only and does not include broader use in autism.[1][3]