MITOCHONDRIAL DISEASES ASSOCIATED WITH CEREBRAL FOLATE DEFICIENCY

Abstract

Cerebral folate deficiency (CFD) has been defined as any neuropsychiatric condition associated with isolated lowering of 5-methyltetrahydrofolate (5-MTHF) levels in CSF and normal systemic folate metabolism.1 CFD has been detected in the infantile-onset CFD syndrome (mediated by serum folate receptor [FR] autoantibodies of the blocking type1) and Aicardi-Goutieres and Rett syndromes. In Kearns-Sayre syndrome (KSS), systemic folate deficiency or low CSF 5-MTHF have long been recognized.2,3 Because active transport of 5-MTHF across the choroid plexus epithelial cells is mediated by ATP-dependent processes, we conducted a study to determine CSF 5-MTHF in a series of patients with mitochondrial disorders. ### Methods. Twenty-eight patients with different mitochondrial disorders and fulfilling the previously defined diagnostic criteria4 were recruited from the Hospital Sant Joan de Deu, Barcelona, Spain (21 patients), the University Clinic Aachen, Germany (5 patients), and Hospital 12 de Octubre, Madrid, Spain (2 patients). Diagnosis included KSS (5 patients), neuropathy, ataxia, and retinitis pigmentosa (1 patient), mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke (1 patient), and various clinically heterogeneous respiratory chain enzyme deficiencies (RCD) (21 patients). Brain MRI was performed for each patient. Serum folate and CSF 5-MTHF, glucose, protein, and cells were determined as per established protocol.5 CSF 5-MTHF …