Cerebral folate deficiency in adults: A heterogeneous potentially treatable condition.

OBJECTIVE: To describe the phenotype and the response to folinic acid supplementation of cerebral folate deficiency (CFD) in adults, a disorder diagnosed on low 5-methyltetrahydro-folate (5MTHF) in cerebrospinal fluid (CSF), which can correspond to a inherited disorder of folate metabolism (IDFM) or to a metabolic consequence of various neurological diseases. METHODS: We conducted a retrospective study on 224 adult patients with neurological symptoms who had a 5MTHF CSF dosage, collecting their neurologic and neuroimaging data. RESULTS: 69 patients had CFD (CSF 5MTHF level < 41 nmol/L), 25 of them had severe CFD (sCFD; ≤25 nmol/L) with adult onset neurological symptoms in 41%. 56% of sCFD patients had an underlying identified neurologic disorder, mainly mitochondrial diseases, hepatic encephalopathy and primary brain calcifications (no identified IDFM), the others were classified as undiagnosed. sCFD patients presented most frequently pyramidal syndrome (75%), movement disorders (56%), cerebellar syndrome (50%) and intellectual disability (46%). MRI findings mostly showed white matter abnormalities (WMA; 32%) and calcifications (12%), and were normal in 23%. The clinico-radiological phenotype of sCFD patients was not clearly different from non CFD patients in terms of manifestations frequency. However, their neurological picture was more complex with a higher number of combined neurological symptoms (4.7±1.6 vs 3.4±1.7, p = .01). In Magnetic Resonance Spectroscopy (MRS), Choline/Creatine (Cho/Cr) ratio was lower in sCFD patients (n = 7) compared to non-CFD patients (n = 73) (p = .005), with good sensitivity (71%) and excellent specificity (92%). Among twenty-one CFD patients treated with folinic acid, nine had a sustained improvement, all with sCFD but one (50% of sCFD patients improved). In two undiagnosed patients with extremely low 5MTHF CSF values, MRI WMA and low Cho/Cr ratios, folinic acid treatment leaded to a dramatic clinical and radiological improvement. CONCLUSION: CSF 5MTHF dosage should be considered in patients with mitochondrial diseases, primary brain calcifications and unexplained complex neurological disorders especially if associated with WMA, since folinic acid supplementation in patients with sCFD is frequently efficient.

Genetic assessment and folate receptor autoantibodies in infantile-onset cerebral folate deficiency (CFD) syndrome.

INTRODUCTION: Cerebral folate deficiency (CFD) syndromes are defined as neuro-psychiatric conditions with low CSF folate and attributed to different causes such as autoantibodies against the folate receptor-alpha (FR) protein that can block folate transport across the choroid plexus, FOLR1 gene mutations or mitochondrial disorders. High-dose folinic acid treatment restores many neurologic deficits. STUDY AIMS AND METHODS: Among 36 patients from 33 families the infantile-onset CFD syndrome was diagnosed based on typical clinical features and low CSF folate. All parents were healthy. Three families had 2 affected siblings, while parents from 4 families were first cousins. We analysed serum FR autoantibodies and the FOLR1 and FOLR2 genes. Among three consanguineous families homozygosity mapping attempted to identify a monogenetic cause. Whole exome sequencing (WES) was performed in the fourth consanguineous family, where two siblings also suffered from polyneuropathy as an atypical finding. RESULTS: Boys (72%) outnumbered girls (28%). Most patients (89%) had serum FR autoantibodies fluctuating over 5-6 weeks. Two children had a genetic FOLR1 variant without pathological significance. Homozygosity mapping failed to detect a single autosomal recessive gene. WES revealed an autosomal recessive polynucleotide kinase 3´phosphatase (PNKP) gene abnormality in the siblings with polyneuropathy. DISCUSSION: Infantile-onset CFD was characterized by serum FR autoantibodies as its predominant pathology whereas pathogenic FOLR1 gene mutations were absent. Homozygosity mapping excluded autosomal recessive inheritance of any single responsible gene. WES in one consanguineous family identified a PNKP gene abnormality that explained the polyneuropathy and also its contribution to the infantile CFD syndrome because the PNKP gene plays a dual role in both neurodevelopment and immune-regulatory function. Further research for candidate genes predisposing to FRα-autoimmunity is suggested to include X-chromosomal and non-coding DNA regions.

[Two cases with generalized intracranial calcification due to hereditary folate malabsorption and literature review].

Objective: This study aimed to investigate the clinical, biochemical and genetic features of two Chinese children with hereditary folate malabsorption. Method: Clinical features, laboratory examinations, treatment and SLC46A1 gene of two cases were studied. Reports on hereditary folate malabsorption utill September of 2016 were searched and the clinical and genetic characteristics of reported cases were summarized. Result: The two patients presented with megaloblastic anemia from their infant period and seizures, psychomotor retardation and regression. In case1, mean corpuscular volume (MCV) was 100 fl. Serum folate was 9.96 nmol/L. Folate and 5-methylenetetrahydrofolate in cerebrospinal fluid were 0 and 0.01 separately. In case 2, MCV was 93.9 fl. Serum folate was 4.49 nmol/L. The concentration of folate and 5-methylenetetrahydrofolate in cerebrospinal fluid were both zero. On their brain CT, progressive bilateral symmetrical calcification was observed. On their SLC46A1 gene, four mutations were identified. Case 1 had one novel mutation, c. 1238T>C (L413P) and c. 194-195insG (p.Cys66LeufsX99). From Case 2, two reported mutations, c. 1A>T (M1L) and c. 194-195insG (p.Cys66LeufsX99) were identified. The administration of folinic acid (60 to 120 mg per day) was initiated after diagnosis. Clinical improvement and normalized hematologic markers were observed after treatment. Totally 37 cases were reported in reviewed English literature, including 30 cases with mutations on SLC46A1 gene (only one Chinese patient). All the cases had the onset in infancy. The ratio of boys to girls was 1 to 1.5. Main manifestations were characterized by megaloblastic anemia (77%), failure to thrive (50%), diarrhea (27%), psychomotor retardation (63.6%), epilepsy (27%), and infection of respiratory system (45.5%). The concentration of folate in both serum and cerebrospinal fluid was decreased (72.7% and 63.6% respectively). Hypoimmunoglobulinemia accounted for 27.3%. Most of mutations in HFM were distributed between p. 65 and p. 68 (c.194-c.204), mainly due to insertion- or deletion-related frame shifts or generation of stop codons. Oral and parenteral folinic acid treatment was effective. Conclusion: Hereditary folate malabsorption often presented with megaloblastic anemia, abnormalities of digestive and nervous system, and hypoimmunoglobulinemia with recurrent infections. Low level of serum and CSF folate and screening SLC46A1 gene are keys to the etiologic study of the patients. Early supplement with folinic acid is beneficial to the prognosis.

S-adenosylmethionine and S-adenosylhomocysteine in plasma and cerebrospinal fluid in Rett syndrome and the effect of folinic acid supplementation.

Rett syndrome is a neurodevelopmental disorder characterized by cognitive and locomotor regression and stereotypic hand movements. The disorder is caused by mutations in the X chromosomal MECP2 a gene encoding methyl CpG-binding protein. It has been associated with disturbances of cerebral folate homeostasis, as well as with speculations on a compromised DNA-methylation. Folinic acid is the stable form of folate. Its derived intermediate 5-MTHF supports the conversion of homocysteine to methionine, the precursor of S-adenosylmethionine (SAM). This in turn donates its methyl group to various acceptors, including DNA, thereby being converted to S-adenosylhomocysteine (SAH). The SAM/SAH ratio reflects the methylation potential. The goal of our study was to influence DNA methylation processes and ameliorate the clinical symptoms in Rett syndrome. Therefore we examined the hypothesis that folinic acid supplementation, besides increasing cerebrospinal fluid (CSF) 5-MTHF (p = 0.003), influences SAM and SAH and their ratio. In our randomized, double-blind crossover study on folinic acid supplementation, ten female Rett patients received both folinic acid and placebo for 1 year each. It was shown that both SAM and SAH levels in the CSF remained unchanged following folinic acid administration (p = 0.202 and p = 0.097, respectively) in spite of a rise of plasma SAM and SAH (p = 0.007; p = 0.009). There was no significant change in the SAM/SAH ratio either in plasma or CSF. The apparent inability of Rett patients to upregulate SAM and SAH levels in the CSF may contribute to the biochemical anomalies of the Rett syndrome. Our studies warrant further attempts to promote DNA methylation in the true region of interest, i.e. the brain.

Addressing a folate imbalance in fetal cerebrospinal fluid can decrease the incidence of congenital hydrocephalus.

Fetal-onset hydrocephalus (HC), which affects between 1:500 and 1:5000 live human births, results from unequal production and drainage of cerebrospinal fluid (CSF) and is associated with abnormal development of the cerebral cortex leading to severe neurological deficits. We previously found that in the hydrocephalic Texas rat, the CSF of affected fetuses induced a cell cycle arrest in neural progenitor cells. Here, we show that alterations in folate metabolism in the CSF of the developing cerebrum are likely responsible for this effect. We identified 3 folate enzymes in the CSF and demonstrate that low levels of one of these, 10-formyltetrahydrofolate dehydrogenase, are associated with HC in the hydrocephalic Texas rat. Therefore, we tested whether supplementation with specific folate species would improve developmental outcome. After daily administration of a combination of tetrahydrofolic and 5-formyltetrahydrofolic acids to pregnant dams, there was a significant reduction in the incidence of HC and improved brain development. By contrast, supplementation with folic acid increased the incidence of congenital HC in this model. These results indicate the complexities of folate metabolism in the developing brain and suggest that folate imbalance leading to HC in the hydrocephalic Texas rat fetuses can be treated with maternal folate supplementation using specific folate metabolites and combinations thereof.

Evaluation of CSF neurotransmitters and folate in 25 patients with Rett disorder and effects of treatment.

BACKGROUND: Rett disorder (RD) is a progressive neurodevelopmental entity caused by mutations in the MECP2 gene. It has been postulated that there are alterations in the levels of certain neurotransmitters and folate in the pathogenesis of this disease. Here we re-evaluated this hypothesis. PATIENTS AND METHODS: We evaluated CSF folate, biogenic amines and pterines in 25 RD patients. Treatment with oral folinic acid was started in those cases with low folate. Patients were clinically evaluated and videotaped up to 6 months after therapy. RESULTS: CSF folate was below the reference values in 32% of the patients. Six months after treatment no clinical improvement was observed. Three of the four patients with the R294X mutation had increased levels of a dopamine metabolite associated to a particular phenotype. Three patients had low levels of a serotonin metabolite. Two of them were treated with fluoxetine and one showed clinical improvement. No association was observed between CSF folate and these metabolites, after adjusting for the patients age and neopterin levels. CONCLUSION: Our results support that folinic acid supplementation has no significant effects on the course of the disease. We report discrete and novel neurotransmitter abnormalities that may contribute to the pathogenesis of RD highlighting the need for further studies on CSF neurotransmitters in clinically and genetically well characterized patients.

Folate receptor autoimmunity and cerebral folate deficiency in low-functioning autism with neurological deficits.

Reduced folate transport to the CNS was identified in two autism spectrum disorders, i.e., Rett syndrome and infantile low-functioning autism with neurological abnormalities. Twenty-five patients with early-onset low-functioning autism with or without neurological deficits, were evaluated for serum folate, cerebrospinal fluid (CSF) 5-methyltetrahydrofolate (5MTHF), and serum FR autoantibodies of the blocking type to determine the significance of folate receptor (FR) autoantibodies with respect to folate transport across the blood-CSF barrier. In spite of normal serum folate, CSF 5MTHF was low in 23 of 25 patients. The reduced CSF folate in 19 of these 23 patients could be explained by serum FR autoantibodies blocking the folate binding site of the membrane-attached FR on the choroid epithelial cells. Oral folinic acid supplements led to normal CSF 5MTHF and partial or complete clinical recovery after 12 months. Serum FR autoimmunity appears to represent an important factor in the pathogenesis of reduced folate transport to the nervous system among children with early-onset low-functioning autism associated with or without neurological deficits. Early detection of FR autoantibodies may be a key factor in the prevention and therapeutic intervention among this subgroup of patients with autism.

Cerebral folate deficiency and leukoencephalopathy caused by a mitochondrial DNA deletion.

OBJECTIVE: Our aim was to describe a child with an incomplete form of Kearns-Sayre syndrome who presented profound cerebrospinal fluid (CSF) folate deficiency and his response to folinic acid supplementation METHODS: CSF 5-methyltetrahydrofolate was analyzed by HPLC with fluorescence detection and mitochondrial DNA deletions by southern blot hybridization. RESULTS: Cranial magnetic resonance imaging showed a leukoencephalopathy. Profound CSF 5-methyltetrahydrofolate deficiency was observed with normal blood folate values and decreased CSF/serum folate ratio, suggesting a transport defect across the blood-brain barrier. Folinic acid treatment was established, and after 1 year clinical response to folinic supplementation was remarkable, with almost normal white matter image. INTERPRETATION: The clinical response after folinic therapy highlights the need for the study of cerebral folate deficiency in patients with mitochondrial disorders and white matter lesions.

Cerebrospinal fluid concentrations of folate, biogenic amines and pterins in Rett syndrome: treatment with folinic acid.

BACKGROUND: Previous studies in Rett syndrome (RS) patients suggested various abnormalities in biogenic amines, pterins, and folate values in cerebrospinal fluid (CSF). Our aim was to analyse these metabolites in CSF of 16 RS patients (age range: 2 - 23 years). Biogenic amines, pterins, and 5-methyltetrahydrofolate were measured by HPLC with electrochemical and fluorescence detection. RESULTS: CSF values of 5-methyltetrahydrofolate were decreased in 8 out of 16 RS patients (average: 53.6 nmol/L; range: 19 - 92) when compared with our reference values (average: 74.6 nmol/L; range: 45 - 127). These eight patients had epilepsy, while 4 out of 16 RS patients who did not have epilepsy showed normal CSF 5-methyltetrahydrofolate concentrations. Values of biogenic amines or pterins were decreased in four of the patients with low values of 5-methyltetrahydrofolate. No correlation was observed between CSF values of 5-methyltetrahydrofolate and pterins, biogenic amines, or age. Supplementation with folinic acid was applied in six out of the eight patients with CSF 5-methyltetrahydrofolate deficiency. An improvement was noticed in all cases. CONCLUSIONS: An important percentage of RS patients showed 5-methyltetrahydrofolate concentrations under the reference values. Therefore, analysis of CSF 5-methyltetrahydrofolate seems advisable in RS, especially in patients with epilepsy and those resistant to antiepileptic drugs.

Latent coeliac disease in a child with epilepsy, cerebral calcifications, drug-induced systemic lupus erythematosus and intestinal folic acid malabsorption associated with impairment of folic acid transport across the blood-brain barrier.

UNLABELLED: A 15-year-old boy with epilepsy and cerebral calcifications, treated with valproic acid, ethyl phenylbarbiturate and ethosuximide, was referred for drug induced systemic lupus erythematosus. Anti-gliadin (AGA) and anti-endomysium (EMA) antibody tests were both positive (EMA titre 1:50). Endoscopic duodenal biopsy showed intense chronic inflammation without villous atrophy or crypt hyperplasia. The child was discharged with a gluten-containing diet. The follow-up showed an increase in EMA titre (1:200) and the persistence of AGA. After 15 months, a second endoscopic intestinal biopsy showed flat mucosa and villous atrophy. Three serum folic acid determinations showed 1.8, 2.4, 2.0 ng/ml (reference range 2.5-16.9 ng/ml) prior to the two intestinal biopsies, but returned to normal levels (11.8 ng/ml) after a gluten-free diet and oral supplementation together. Two years later, the frequency of epileptic seizures was unchanged despite ongoing anti-epileptic treatment and a gluten-free diet. As cerebral calcification and epilepsy are reminiscent of the findings in congenital folate malabsorption, oral loading tests with 5 mg folic acid were carried out and showed impaired intestinal absorption and a defect in the transport across the blood-brain barrier. Low CSF folate levels (13.9 and 12.6 ng/ml, reference range 15-40 ng/ml) and an alteration in the CSF/serum folate ratio (1.43 and 1.16, normal ratio 3:1) were also found as well as increased levels of cystathionine both in CSF (40 micromol/l, reference range 18-28 micromol/l) and in serum (32 micromol/l, reference value <0.10 micromol/l). CONCLUSION: Impairment of intestinal folic acid absorption with a defect in folic acid transport across the blood-brain barrier has been demonstrated in a case of epilepsy and cerebral calcifications associated with coeliac disease.