Cerebral folate deficiency is a condition in which concentrations of 5-methyltetrahydrofolate are low in the brain as measured in the cerebral spinal fluid despite being normal in the blood. Symptoms typically appear at about 5 to 24 months of age. Without treatment there may be poor muscle tone, trouble with coordination, trouble talking, and seizures. One cause of cerebral folate deficiency is a mutation in a gene responsible for folate transport, specifically FOLR1. This is inherited in an autosomal recessive manner. Other causes appear to be Kearns–Sayre syndrome and autoantibodies to the folate receptor. For people with the FOLR1 mutation, even when the systemic deficiency is corrected by folate, the cerebral deficiency remains and must be treated with folinic acid. Success depends on early initiation of treatment and treatment for a long period of time. Fewer than 20 people with the FOLR1 defect have been described in the medical literature. From Wikipedia
