Folate, or vitamin B9, plays a crucial role in brain development, and many children with autism have been found to have low brain folate levels, a condition known as Cerebral Folate Deficiency (CFD). Folate is important for the metabolism of purines and pyrimidines, which are essential for RNA, DNA, and energy production. CFD is a recently identified disorder characterized by low levels of 5-MTHF (the bioavailable form of folate) in the cerebrospinal fluid, despite having normal or elevated levels in the blood.