Cerebral folate transporter deficiency: a potentially treatable neurometabolic disorder.

Cerebral folate deficiency (CFD) syndrome is a rare treatable neurometabolic disorder with low levels of the active form of folaten in cerebrospinal fluid (CSF) arising from different causes such as FOLR1 gene mutations or autoantibodies against the folate receptor-alpha (FR) protein that can block folate transport across the choroid plexus. It is characterized by late infantile onset refractory seizures, ataxia, movement disorder, and unexplained global developmental delay. Here, we report a patient diagnosed with autistic spectrum disorder, followed by refractory myoclonic-atonic seizures, ataxia, and loss of motor skills over time. A homozygous missense (c.665A > G) mutation in FOLR1 gene and extremely low CSF 5-methyltetrahydrofolate level led to the diagnosis of CFD. Although she was initiated on combined oral and intravenous high doses of folinic acid treatment at 6 years of age, mild improvement was achieved in terms of epileptic seizures and motor skills. It is important that CFD should be kept in mind in cases with refractory myoclonic-atonic seizure and folinic acid treatment should be started as soon as possible.