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Copyright of Gyermekgyógyászat is the property of Semmelweis Kiado and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BackgroundCerebral folate transport deficiency (CFD) is a rare neurological disease characterized by a deficiency in 5-methyltetrahydrofolate (5-MTHF) in the cerebrospinal fluid, with a normal peripheral total folate level. Late infantile-onset refractory seizures, ataxia, movement disorders, hypotonia, developmental delays, and developmental regression characterize CFD. Some patients present with visual and hearing impairments and autism-like manifestations. This study aimed to elucidate the clinical features, diagnostic approach, and therapeutic outcomes in siblings with CFD due to FOLR1 variants, highlighting the importance of early diagnosis and treatment.Case presentationWe reported the cases of two siblings with CFD caused by a new variant in FOLR1. They presented with intractable epilepsy, developmental regression, and ataxia, and the younger sibling developed autism. Whole-exon sequencing revealed a c.148G>A homozygous variant, resulting in a change in the amino acid sequence (p.Glu50Lys). Low 5-MTHF levels were detected in the cerebrospinal fluid.ConclusionsThis report illustrates that CFD was caused by FOLR1 variants in two siblings. They had intractable epilepsy, developmental regression, and ataxia, and a diagnosis of CFD was confirmed by a c.148G>A (p.Glu50Lys) variant in FOLR1, a new pathogenic variant in FOLR1. Early diagnosis is essential and can improve outcomes in affected patients.

Cerebral folate transport deficiency, caused by a genetic defect in folate receptor α, is a devastating neurometabolic disorder that, if untreated, leads to epileptic encephalopathy, psychomotor decline and hypomyelination. Currently, there are limited data on effective dosage and duration of treatment, though early diagnosis and therapy with folinic acid appears critical. The aim of this long‐term study was to identify new therapeutic approaches and novel biomarkers for assessing efficacy, focusing on myelin‐sensitive MRI. Clinical, biochemical, structural and quantitative MRI parameters of seven patients with genetically confirmed folate receptor α deficiency were acquired over 13 years. Multimodal MRI approaches comprised MR‐spectroscopy (MRS), magnetization transfer (MTI) and diffusion tensor imaging (DTI) sequences. Patients started oral treatment immediately following diagnosis or in an interval of up to 2.5 years. Escalation to intravenous and intrathecal administration was performed in the absence of effects. Five patients improved, one with a presymptomatic start of therapy remained symptom‐free, and one with inconsistent treatment deteriorated. While CSF 5‐methyltetrahydrofolate and MRS parameters normalized immediately after therapy initiation, myelin‐sensitive MTI and DTI measures correlated with gradual clinical improvement and ongoing myelination under therapy. Early initiation of treatment at sufficient doses, considering early intrathecal applications, is critical for favorable outcome. The majority of patients showed clinical improvements that correlated best with MTI parameters, allowing individualized monitoring of myelination recovery. Presymptomatic therapy seems to ensure normal development and warrants newborn screening. Furthermore, the quantitative parameters of myelin‐sensitive MRI for therapy assessments can now be used for hypomyelination disorders in general. [ABSTRACT FROM AUTHOR]

Abstract Background Neurodegeneration due to cerebral folate transport deficiency is a rare autosomal recessive disorder caused by biallelic pathogenic variants in FOLR1. Onset typically occurs in late infancy and is characterized by psychomotor regression, epilepsy, and a hypomyelinating leukodystrophy on magnetic resonance imaging. If left untreated, progressive neurodegeneration occurs. However, early treatment with folinic acid has been shown to stabilize or reverse neurological features. Approximately thirty patients have been described worldwide. Here, we report the first two cases with genetically proven cerebral folate transport deficiency from South-Eastern Europe, describe the effect of oral folinic acid therapy on clinical and neuroradiological features and review the literature. Results Two siblings presented in childhood with clinical and radiological findings consistent with a hypomyelinating leukodystrophy. Exome sequencing revealed a novel homozygous pathogenic variant in FOLR1 (c.465_466delinsTG; p.W156G), confirming the diagnosis of neurodegeneration due to cerebral folate transport deficiency. Folinic acid treatment was promptly initiated in both patients. The younger sibling was treated early in disease course at 2 years of age, and demonstrated complete recovery in clinical and MRI features. The older sibling, who was 8 years of age at the time of diagnosis and treatment, demonstrated partial but substantial improvements. Conclusion We present the first account in the literature that early treatment initiation with oral folinic acid alone can result in complete neurological recovery of both clinical and radiological abnormalities in neurodegeneration due to cerebral folate deficiency. Moreover, through the report of these patients along with review of the literature, we provide information about the natural history of the disease with comparison of treatment effects at different stages of disease progression. This report also reinforces the importance of universal access to genetic testing to ensure prompt diagnoses for treatable disorders.

With the rapid advancement of medical technologies in genomic and molecular medicine, the number of treatable neurometabolic diseases is quickly expanding. Spastic paraplegia 56 (SPG56), one of the severe autosomal recessive forms of neurodegenerative disorders caused by pathogenic variants in the CYP2U1 gene, has no reported specific targeted treatment yet. Here we report 2 Chinese brothers with CYP2U1 bi-allelic pathogenic variants with cerebral folate deficiency who were treated for over a decade with folinic acid supplement. Patients have remained stable under therapy.

Background: Folates (Vitamin B9) are critical for normal neurodevelopment and function, with transport mediated by three major pathways: folate receptor alpha (FRα), proton-coupled folate transporter (PCFT), and reduced folate carrier (RFC). Cerebral folate uptake primarily occurs at the blood-cerebrospinal fluid barrier (BCSFB) through concerted actions of FRα and PCFT, with impaired folate transport resulting in the neurological disorder cerebral folate deficiency (CFD). Increasing evidence suggests that disorders associated with CFD also present with neuroinflammation, oxidative stress, and mitochondrial dysfunction, however the role of brain folate deficiency in inducing these abnormalities is not well-understood. Our laboratory has identified the upregulation of RFC by nuclear respiratory factor 1 (NRF-1) at the blood–brain barrier (BBB) once indirectly activated by the natural compound pyrroloquinoline quinone (PQQ). PQQ is also of interest due to its anti-inflammatory, antioxidant, and mitochondrial biogenesis effects. In this study, we examined the effects of folate deficiency and PQQ treatment on inflammatory and oxidative stress responses, and changes in mitochondrial function. Methods: Primary cultures of mouse mixed glial cells exposed to folate-deficient (FD) conditions and treated with PQQ were analyzed for changes in gene expression of the folate transporters, inflammatory markers, oxidative stress markers, and mitochondrial DNA (mtDNA) content through qPCR analysis. Changes in cellular reactive oxygen species (ROS) levels were analyzed in vitro through a DCFDA assay. Wildtype (C57BL6/N) mice exposed to FD (0 mg/kg folate), or control (2 mg/kg folate) diets underwent a 10-day (20 mg/kg/day) PQQ treatment regimen and brain tissues were collected and analyzed. Results: Folate deficiency resulted in increased expression of inflammatory and oxidative stress markers in vitro and in vivo, with increased cellular ROS levels observed in mixed glial cells as well as a reduction of mitochondrial DNA (mtDNA) content observed in FD mixed glial cells. PQQ treatment was able to reverse these changes, while increasing RFC expression through activation of the PGC-1α/NRF-1 signaling pathway. Conclusion: These results demonstrate the effects of brain folate deficiency, which may contribute to the neurological deficits commonly seen in disorders of CFD. PQQ may represent a novel treatment strategy for disorders associated with CFD, as it can increase folate uptake, while in parallel reversing many abnormalities that arise with brain folate deficiency. [ABSTRACT FROM AUTHOR]

Background: Refractory depression is a devastating condition with significant morbidity, mortality, and societal cost. Approximately 15% of patients with major depressive disorder are refractory to currently available treatments. We hypothesized metabolic abnormalities contributing to treatment refractory depression are associated with distinct findings identifiable in the cerebrospinal fluid (CSF). Our hypothesis was confirmed by a previous small case-controlled study. Here we present a second, larger replication study. Methods: We conducted a case-controlled, targeted, metabolomic evaluation of 141 adolescent and adult patients with well-characterized history of depression refractory to three maximum-dose, adequate-duration medication treatments, and 36 healthy controls. Plasma, urine, and CSF metabolic profiling were performed by coupled gas chromatography/mass spectrometry, and high-performance liquid chromatography, electrospray ionization, tandem mass spectrometry. Results: Abnormalities were identified in 67 of 141 treatment refractory depression participants. The CSF abnormalities included: low cerebral folate (n = 20), low tetrahydrobiopterin intermediates (n = 11), and borderline low-tetrahydrobiopterin intermediates (n = 20). Serum abnormalities included abnormal acylcarnitine profile (n = 12) and abnormal serum amino acids (n = 20). Eighteen patients presented with two or more abnormal metabolic findings. Sixteen patients with cerebral folate deficiency and seven with low tetrahydrobiopterin intermediates in CSF showed improvement in depression symptom inventories after treatment with folinic acid and sapropterin, respectively. No healthy controls had a metabolite abnormality. Conclusions: Examination of metabolic disorders in treatment refractory depression identified an unexpectedly large proportion of patients with potentially treatable abnormalities. The etiology of these abnormalities and their potential roles in pathogenesis remain to be determined. [ABSTRACT FROM AUTHOR]

Background: Neurodegeneration due to cerebral folate transport deficiency is a rare autosomal recessive disorder caused by biallelic pathogenic variants in FOLR1. Onset typically occurs in late infancy and is characterized by psychomotor regression, epilepsy, and a hypomyelinating leukodystrophy on magnetic resonance imaging. If left untreated, progressive neurodegeneration occurs. However, early treatment with folinic acid has been shown to stabilize or reverse neurological features. Approximately thirty patients have been described worldwide. Here, we report the first two cases with genetically proven cerebral folate transport deficiency from South-Eastern Europe, describe the effect of oral folinic acid therapy on clinical and neuroradiological features and review the literature. Results: Two siblings presented in childhood with clinical and radiological findings consistent with a hypomyelinating leukodystrophy. Exome sequencing revealed a novel homozygous pathogenic variant in FOLR1 (c.465_466delinsTG; p.W156G), confirming the diagnosis of neurodegeneration due to cerebral folate transport deficiency. Folinic acid treatment was promptly initiated in both patients. The younger sibling was treated early in disease course at 2 years of age, and demonstrated complete recovery in clinical and MRI features. The older sibling, who was 8 years of age at the time of diagnosis and treatment, demonstrated partial but substantial improvements. Conclusion: We present the first account in the literature that early treatment initiation with oral folinic acid alone can result in complete neurological recovery of both clinical and radiological abnormalities in neurodegeneration due to cerebral folate deficiency. Moreover, through the report of these patients along with review of the literature, we provide information about the natural history of the disease with comparison of treatment effects at different stages of disease progression. This report also reinforces the importance of universal access to genetic testing to ensure prompt diagnoses for treatable disorders. [ABSTRACT FROM AUTHOR]

Neurodevelopmental disorders (NDDs) have broad heterogeneity both clinically and genetically. Inborn errors of metabolism can be one of the reasons of neurodevelopmental disruption causing specific NDDs. Although there is tremendous advance in molecular identification via next-generation sequencing (NGS), there are still many unsolved patients with NDD. Reanalysis of NGS data with different pipelines can at least partially accomplish this challenge. Herein, we report clinic and genetic components of an adult sib-pair with an undiagnosed NDD condition, which has been solved through reanalysis of whole-exome sequencing (WES). Parallel analysis of SNP-based genotyping and WES was performed to focus on variants only in loci with positive logarithm of the odds scores. WES data was analyzed through three different pipelines with two distinct bed files. Reanalysis of WES data led us to detect a homozygous FOLR1 variant (ENST00000393676.5:c.610C > T, p.(Arg204Ter), rs952165627) in the affected sib-pair. Surprisingly, the variant could not be detected in the first analysis as the variant region is not included in the first bed file which may frequently be used. Biochemical tests of CSF have confirmed the genetic analysis, CSF folic acid levels were detected low in sib-pair, and intravenous folinic acid treatment improved the disease course for the first 6 months of follow-up even at late diagnosis age. Although combined analysis of SNP-based genotyping and WES is a powerful tool to reveal the genetic components of heterogeneous diseases, reanalysis of genome data still should be considered in unsolved patients. Also, biochemical screening helps us to decipher undiagnosed NDD that may be a treatable neurometabolic condition. [ABSTRACT FROM AUTHOR]

Abstract Objective The use of folic acid (FA) has been discouraged in cerebral folate deficiency (CFD) because, theoretically, it could inhibit the transport of 5‐methyltetrahydrofolic acid (5MTHF) across the blood–cerebrospinal fluid (CSF) barrier. We present the clinical biochemical data of two cases with CFD to support this hypothesis. Methods We measured CSF and serum 5MTHF concentrations in a patient with Kearns‐Sayre syndrome (KSS) and a patient homozygous for MTHFR C677T polymorphism before and during folate supplementation therapy. To evaluate these 5MTHF concentrations, we also analyzed CSF and serum samples in pediatric patients without folate supplementation. Results Both patients had low CSF 5MTHF before treatment and high‐dose FA therapy did not normalize CSF 5MTHF. There was a dissociation between serum total folate and 5MTHF concentrations during FA therapy, which was considered to be due to the appearance of unmetabolized FA. The addition of folinic acid did not improve low CSF 5MTHF in the KSS patient and the cessation of FA resulted in the normalization of CSF 5MTHF. In the patient homozygous for MTHFR C677T, minimization of the FA dosage resulted in the normalization of CSF 5MTHF and an increased CSF‐to‐serum 5MTHF ratio. Conclusions Our data suggest that excess supplementation of FA impaired 5MTHF transport across the blood–CSF barrier. In the treatment of CFD, supplementation of folinic acid or 5MTHF (in cases of impaired 5MTHF synthesis) is preferred over the use of FA. The reference values of CSF 5MTHF concentration based on 600 pediatric cases were also provided.

Cerebral folate deficiency (CFD) is a rare progressive neurological condition characterized by normal blood folate level and low 5-methyltetrahydrofolate (5-MTHF) levels in the cerebrospinal fluid. Patients present with different neurological findings including hypotonia and microcephaly. Later, patients develop ataxia, seizures, para or quadri-plagia. Herein, we report two siblings; born to consanguineous parents; who had normal neurological development in early childhood. Subsequently they developed drug-resistant seizures, neurological regression, and spastic quadriplegia. After thorough investigations patients had brain MRI which showed abnormal white matter signals and ventricular dilatation, CSF with low 5-MTHF, and whole exome sequencing (WES) revealed a novel homozygous variant in FOLR1 (c.245A > G; p.Tyr82Cys) consistent with the diagnosis of cerebral folate deficiency. They were treated with folinic acid in addition to standard anti-seizure medications. WES aids in reaching CFD diagnosis due to FOLR1 pathogenic variants. These results can be used for future counselling to prevent recurrence in future pregnancies by preimplantation genetic testing prior to implanting the embryo in the uterus. Treatment with folinic acid was shown to improve the neurological symptoms namely reduced the seizures and spasticity.

In a rat model, following exposure to rat folate receptor alpha antibodies (FRαAb) during gestation, FRαAb accumulates in the placenta and the fetus and blocks folate transport to the fetal brain and produces behavioral deficits in the offspring. These deficits could be prevented with folinic acid. Therefore, we sought to evaluate folate transport to the brain in young rat pups and determine what effect FRαAb has on this process, to better understand the folate receptor autoimmune disorder associated with cerebral folate deficiency (CFD) in autism spectrum disorders (ASD). When injected intraperitoneally (IP), FRαAb localizes to the choroid plexus and blood vessels including the capillaries throughout the brain parenchyma. Biotin-tagged folic acid shows distribution in the white matter tracts in the cerebrum and cerebellum. Since these antibodies can block folate transport to the brain, we orally administered various folate forms to identify the form that is better-absorbed and transported to the brain and is most effective in restoring cerebral folate status in the presence of FRαAb. The three forms of folate, namely folic acid, D,L-folinic acid and levofolinate, are converted to methylfolate while L-methylfolate is absorbed as such and all are efficiently distributed to the brain. However, significantly higher folate concentration is seen in the cerebrum and cerebellum with levofolinate in the presence or absence of FRαAb. Our results in the rat model support testing levofolinate to treat CFD in children with ASD. [ABSTRACT FROM AUTHOR]

Simple Summary: Cerebral folate deficiency syndrome (CFD) was defined as any neurological condition that was associated with low concentrations of 5-methyltetrahydrofolate in the cerebrospinal fluid. Previous clinical studies have suggested that mutations in the folate receptor alpha (FOLR1) gene contribute to CFD. In this study, we identified six genetic variants in histone lysine demethylase 6B (KDM6B) in 48 CFD cases. We demonstrated that these KDM6B variants decreased FOLR1 protein expression by manipulating epigenetic markers regulating chromatin organization and gene expression. In addition, FOLR1 autoantibodies were identified in CFD patients' serum. To the best of our knowledge, this is the first study to report that KDM6B may be a novel CFD candidate gene in humans. (1) Background: The genetic etiology of most patients with cerebral folate deficiency (CFD) remains poorly understood. KDM6B variants were reported to cause neurodevelopmental diseases; however, the association between KDM6B and CFD is unknown; (2) Methods: Exome sequencing (ES) was performed on 48 isolated CFD cases. The effect of KDM6B variants on KDM6B protein expression, Histone H3 lysine 27 epigenetic modification and FOLR1 expression were examined in vitro. For each patient, serum FOLR1 autoantibodies were measured; (3) Results: Six KDM6B variants were identified in five CFD patients, which accounts for 10% of our CFD cohort cases. Functional experiments indicated that these KDM6B variants decreased the amount of KDM6B protein, which resulted in elevated H3K27me2, lower H3K27Ac and decreased FOLR1 protein concentrations. In addition, FOLR1 autoantibodies have been identified in serum; (4) Conclusion: Our study raises the possibility that KDM6B may be a novel CFD candidate gene in humans. Variants in KDM6B could downregulate FOLR1 gene expression, and might also predispose carriers to the development of FOLR1 autoantibodies. [ABSTRACT FROM AUTHOR]

Background: Folates are a family of B9 vitamins that serve as one-carbon donors critical to biosynthetic processes required for the development and function of the central nervous system (CNS) in mammals. Folate transport is mediated by three highly specific systems: (1) folate receptor alpha (FRα; FOLR1/Folr1), (2) the reduced folate-carrier (RFC; SLC19A1/Slc19a1) and (3) the proton-coupled folate transporter (PCFT; SLC46A1/Slc46a1). Folate transport into and out of the CNS occurs at the blood–cerebrospinal fluid barrier (BCSFB), mediated by FRα and PCFT. Impairment of folate transport at the BCSFB results in cerebral folate deficiency in infants characterized by severe neurological deficiencies and seizures. In contrast to the BCSFB, CNS folate transport at other brain barriers and brain parenchymal cells has not been extensively investigated. The aim of this study is to characterize folate transport systems in the murine CNS at several known barriers encompassing the BCSFB, arachnoid barrier (AB), blood–brain barrier (BBB) and parenchymal cells (astrocytes, microglia, neurons). Methods: Applying immunohistochemistry, localization of folate transport systems (RFC, PCFT, FRα) was examined at CNS barriers and parenchymal sites in wildtype (C57BL6/N) mice. Subcellular localization of the folate transport systems was further assessed in an in vitro model of the mouse AB. Gene and protein expression was analyzed in several in vitro models of brain barriers and parenchyma by qPCR and western blot analysis. Results: RFC, PCFT, and FRα expression was localized within the BCSFB and BBB consistent with previous reports. Only RFC and PCFT expression was detected at the AB. Varied levels of RFC and PCFT expression were detected in neuronal and glial cells. Conclusions: Localization of RFC and PCFT within the AB, described here for the first time, suggest that AB may contribute to folate transport between the peripheral circulation and the CSF. RFC and PCFT expression observed in astrocytes and microglia is consistent with the role that one or both of these transporters may play in delivering folates into cells within brain parenchyma. These studies provide insights into mechanisms of folate transport in the CNS and may enhance our understanding of the critical role folates play in neurodevelopment and in the development of novel treatment strategies for disorders of brain folate deficiency due to impaired transporter function. [ABSTRACT FROM AUTHOR]

Cerebral folate deficiency syndrome (CFDS) is defined as any neuropsychiatric or developmental disorder characterized by decreased CSF folate levels in the presence of normal folate status outside the nervous system. The specific clinical profile appears to be largely determined by the presence or absence of intrauterine folate deficiency as well as postnatal age at which cerebral folate deficiency occurs. The primary cause of CFDS is identified as the presence of serum folate receptor-alpha (FRα) autoantibodies impairing folate transport across the choroid plexus to the brain whereas, in a minority of cases, mitochondrial disorders, inborn errors of metabolism and loss of function mutations of the FRα (FOLR1) gene are identified. Early recognition and diagnosis of CFDS and prompt intervention is important to improve prognosis with successful outcomes. In this article we focus on FRα autoimmunity and its different age-dependent clinical syndromes, the diagnostic criteria, and treatments to be considered, including prevention strategies in this at-risk population. [ABSTRACT FROM AUTHOR]

Abstract Mutations in the FOLR1 gene, encoding for the folate alpha receptor (FRa), represent a rare recessive genetic cause of cerebral folate deficiency (CFD), a potentially reversible neurometabolic condition. Patients typically present with developmental delay, seizures, abnormal movements, and delayed myelination. We hereby expand the phenotypic and genotypic spectrum of the disease with the report of the first two Greek siblings that were found compound heterozygous for one known FOLR1 gene mutation (p.Cys65Trp) and a mutation (p.Trp143Arg) that has not yet been reported in the literature (class 3 variant according to ASHG classification). A distinguishing feature of the older sibling is the manifestation of drug‐resistant epileptic spasms beyond infancy. These had a relatively good response to a ketogenic diet, as an additional treatment to topiramate and valproate. A further clinical improvement was observed when folinic acid was combined with the above treatment. While a response to folinic acid is well established in the disorder, the efficacy of its combination with the ketogenic diet needs further evaluation, but we suggest considering it early in the course of drug resistant epilepsy in the setting of CFD. The younger sibling was diagnosed and treated with folinic acid at an early‐symptomatic stage. Both patients had moderately low age‐related CSF 5‐methyltetrahydrofolate levels at diagnosis with the older sibling (that was already treated at base line collection) averaging 19 nmol/L (normal range: 44‐122 nmol/L) and the younger one 49 nmol/L (normal range 63‐122 nmol/L). These levels were restored to normal limits after folinic supplementation.

Background: Cerebral folate transport deficiency (CFD) is a rare neurological disease characterized by a deficiency in 5-methyltetrahydrofolate (5-MTHF) in the cerebrospinal fluid, with a normal peripheral total folate level. Late infantile-onset refractory seizures, ataxia, movement disorders, hypotonia, developmental delays, and developmental regression characterize CFD. Some patients present with visual and hearing impairments and autism-like manifestations. This study aimed to elucidate the clinical features, diagnostic approach, and therapeutic outcomes in siblings with CFD due to FOLR1 variants, highlighting the importance of early diagnosis and treatment., Case Presentation: We reported the cases of two siblings with CFD caused by a new variant in FOLR1 . They presented with intractable epilepsy, developmental regression, and ataxia, and the younger sibling developed autism. Whole-exon sequencing revealed a c.148G>A homozygous variant, resulting in a change in the amino acid sequence (p.Glu50Lys). Low 5-MTHF levels were detected in the cerebrospinal fluid., Conclusions: This report illustrates that CFD was caused by FOLR1 variants in two siblings. They had intractable epilepsy, developmental regression, and ataxia, and a diagnosis of CFD was confirmed by a c.148G>A (p.Glu50Lys) variant in FOLR1 , a new pathogenic variant in FOLR1 . Early diagnosis is essential and can improve outcomes in affected patients., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2024 Wang, Yang, Yu, Deng, Wen, Yang, Liu and Luo.)

(1) Background: The genetic etiology of most patients with cerebral folate deficiency (CFD) remains poorly understood. KDM6B variants were reported to cause neurodevelopmental diseases; however, the association between KDM6B and CFD is unknown; (2) Methods: Exome sequencing (ES) was performed on 48 isolated CFD cases. The effect of KDM6B variants on KDM6B protein expression, Histone H3 lysine 27 epigenetic modification and FOLR1 expression were examined in vitro. For each patient, serum FOLR1 autoantibodies were measured; (3) Results: Six KDM6B variants were identified in five CFD patients, which accounts for 10% of our CFD cohort cases. Functional experiments indicated that these KDM6B variants decreased the amount of KDM6B protein, which resulted in elevated H3K27me2, lower H3K27Ac and decreased FOLR1 protein concentrations. In addition, FOLR1 autoantibodies have been identified in serum; (4) Conclusion: Our study raises the possibility that KDM6B may be a novel CFD candidate gene in humans. Variants in KDM6B could downregulate FOLR1 gene expression, and might also predispose carriers to the development of FOLR1 autoantibodies.

Copyright of Der Ophthalmologe is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cerebral folate transport deficiency due to folate receptor 1 gene (FOLR1) gene mutation results from impaired folate transport across the blood: choroidplexus: cerebrospinal fluid (CSF) barrier. This leads to low CSF 5-methyltetrahydrofolate, the active folate metabolite. We are reporting two children with this treatable cerebral folate transport deficiency. Eight years and 9-month-old female presented with delayed milestones followed by regression, seizures, and intention tremors. On examination child had microcephaly, generalized hypotonia, hyperreflexia, unsteady gait, and incoordination. Magnetic resonance imaging (MRI) of brain revealed dilated ventricular system and cerebellar atrophy. Computed tomography (CT) of brain showed brain calcifications. Whole exome sequencing was finally performed, revealing homozygous nonsense pathogenic variant in FOLR1 gene in exon 3 c.C382T p.R128W, confirming the diagnosis of cerebral folate deficiency. Twelve-year-old female child presented with global developmental delay since birth, myoclonic jerks and cognitive regression. Child had generalized hypotonia and hyperreflexia. Her coordination was markedly affected with intention tremors andunbalanced gait. CT brain showed bilateral basal ganglia and periventricular calcifications with brain atrophic changes. MRI brain showed a prominent cerebellar folia with mild brain atrophic changes. Genetic testing showed a homozygous pathogenic variant was identified in FOLR1 C.327_328 delinsAC, p.Cys109Ter. Both patients were started on intramuscular folinic acid injections with a decrease in seizure frequency. However, their seizures did not stop completely due to late initiation of therapy. In conclusion, cerebral folate transport deficiency should be suspected in every child with global developmental delay, intractable myoclonic epilepsy, ataxia with neuroimaging suggesting cerebellar atrophy and brain calcifications. Response to folinic acid supplementation is partial if diagnosed late and treatment initiation is delayed., Competing Interests: The authors declare no competing interests., (Copyright © 2024 Korean Epilepsy Society.)

Background: Hereditary folate malabsorption is a multisystem disease owing to biallelic variants in the gene encoding the proton-coupled folate transporter. Hereditary folate malabsorption is treated with folinic acid, aimed to restore blood and cerebrospinal fluid folate levels. Little is known as to whether oral or intramuscular supplementation of folinic acid is most effective.Methods: Here we describe a one-year-old boy with hereditary folate malabsorption presenting with the typical features including failure to thrive, aphthous stomatitis, macrocytic anemia along with severe developmental impairment and epilepsy, as well as a magnetic resonance imaging of the brain showing bilateral occipital, cortical calcifications characteristic of hereditary folate malabsorption. We compared the effect of treatment with oral folinic acid versus intramuscular folinic acid supplementation by measuring plasma and cerebrospinal fluid folate levels.Results: Compared with oral administration, intramuscular treatment resulted in higher folate levels in blood and, most importantly, normalization of folate levels in cerebrospinal fluid. Clinically, nearly all systemic and neurological symptoms resolved.Conclusion: Normal cerebrospinal fluid folate levels can be achieved in individuals with hereditary folate malabsorption with intramuscular (but not with oral) administration of folinic acid. [ABSTRACT FROM AUTHOR]

Abstract 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. Highlights • Cerebral folate deficiency (CFD) has a heterogeneous phenotype in adults. • Particular spectroscopy or MRI patterns can be indicative of CFD. • Some neurological conditions are more often associated with CFD. • Folinic acid substitution may improve patients clinically and radiologically. [ABSTRACT FROM AUTHOR]

Cerebral folate deficiency (CFD) is a neurological disorder characterized by low levels of 5-methyltetrahydrofolate (5-MTHF) in the cerebrospinal fluid (CSF). The prevalence of this autosomal recessive disorder is estimated to be FOLR1) encoding the receptor of folate α (FRα) have already been described. We present a new pathogenic variation in the FOLR1 in a childhood-stage patient. We aim to establish the core structure of the FRα protein mandatory for its activity. A three-year-old child was admitted at hospital for a first febrile convulsions episode. Recurrent seizures without fever also occurred a few months later, associated with motor and cognitive impairment. Various antiepileptic drugs failed to control seizures. Magnetic resonance imaging (MRI) showed central hypomyelination and biological analysis revealed markedly low levels of 5-MTHF in CSF. Next generation sequencing (NGS) confirmed a CFD with a FOLR1 homozygous variation (c.197 G > A, p.Cys66Tyr). This variation induces an altered folate receptor α protein and underlines the role of a disulfide bond: Cys66-Cys109, essential to transport 5-MTHF into the central nervous system. Fortunately, this severe form of CFD had remarkably responded to high doses of oral folinic acid combined with intravenous administrations.

This review offers an update on a group of inborn errors of metabolism causing severe epilepsy with the onset in pediatric age (but also other neurological manifestations such as developmental delay or movement disorders) with available effective or potentially effective treatments. The main pathogenic and clinical features and general recommendations for the diagnostic and therapeutic workup of the following disorders are discussed: vitamin B6-dependent epilepsies, cerebral folate deficiency, congenital disorders of serine metabolism, biotinidase deficiency, inborn errors of creatine metabolism, molybdenum cofactor deficiency, and glucose transporter 1 deficiency. Available treatments are more effective on epileptic manifestations (with the possibility of complete seizure control) and motor symptoms, whereas the benefits on cognitive outcome are usually minor. [ABSTRACT FROM AUTHOR]

Recently, cerebral folate deficiency (CFD) was suggested to be involved in the pathogenesis of autism spectrum disorders (ASD). However, the exact role of folate metabolism in the pathogenesis of ASD, identification of underlying pathogenic mechanisms and impaired metabolic pathways remain unexplained. The aim of our study was to develop and test a novel, unbiased, bioinformatics approach in order to identify links between ASD and disturbed cerebral metabolism by focusing on abnormal folate metabolism, which could foster patient stratification and novel therapeutic interventions. An unbiased, automatable, computational workflow interaction model was developed using available data from public databases. The interaction network model of ASD-associated genes with known cerebral expression and function (SFARI) and metabolic networks (MetScape), including connections to known metabolic substrates, metabolites and cofactors involving folates, was established. Intersection of bioinformatically created networks resulted in a limited amount of interaction modules pointing to common disturbed metabolic pathways, linking ASD to CFD. Two independent interaction modules (comprising three pathways) covering enzymes encoded by ASD-related genes and folate cofactors utilizing enzymes were generated. Module 1 suggested possible interference of CFD with serine and lysine metabolism, while module 2 identified correlations with purine metabolism and inosine monophosphate production. Since our approach was primarily conceived as a proof of principle, further amendments of the presented initial model are necessary to obtain additional actionable outcomes. Our modelling strategy identified not only previously known interactions supported by evidence-based analyses, but also novel plausible interactions, which could be validated in subsequent functional and/or clinical studies. Autism Res 2017, 10: 1424-1435. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Cerebral folate deficiency due to folate receptor 1 gene ( FOLR1 ) mutations is an autosomal recessive disorder resulting from a brain-specific folate transport defect. It is characterized by late infantile onset, severe psychomotor regression, epilepsy, and leukodystrophy. We describe a consanguineous girl exhibiting severe developmental regression, intractable epilepsy, polyneuropathy, and profound hypomyelination with cortical involvement. Magnetic resonance imaging showed cortical disturbances in addition to profound hypomyelination and cerebellar atrophy. Nerve conduction studies revealed both axonal degeneration and demyelinating features. A diagnosis of cerebral folate deficiency was confirmed by a homozygous c.466T>G (p.W156G) mutation in FOLR1 , coupled with extremely low cerebrospinal fluid levels of 5-methyltetrahydrofolate. Her symptoms, neuroradiological findings, and polyneuropathy were alleviated by oral folinic acid treatment in conjunction with intravenous and intramuscular administration therapy. Our patient shows that folinic acid therapy can ameliorate the clinical symptoms, white matter disturbances, cortical insults, and peripheral neuropathy of cerebral folate deficiency caused by FOLR1 mutation. It is important to recognize these clinical symptoms and make a precise diagnosis early on, because cerebral folate deficiency is treatable. [ABSTRACT FROM AUTHOR]

The proton-coupled folate transporter (PCFT-SLC46A1) is the mechanism by which folates are absorbed across the brush-border membrane of the small intestine. The transporter is also expressed in the choroid plexus and is required for transport of folates into the cerebrospinal fluid. Loss of PCFT function, as occurs in the autosomal recessive disorder “hereditary folate malabsorption” (HFM), results in a syndrome characterized by severe systemic and cerebral folate deficiency. Folate-receptor alpha (FRα) is expressed in the choroid plexus, and loss of function of this protein, as also occurs in an autosomal recessive disorder, results solely in “cerebral folate deficiency” (CFD), the designation for this disorder. This paper reviews the current understanding of the functional and structural properties and regulation of PCFT, an electrogenic proton symporter, and contrasts PCFT properties with those of the reduced folate carrier (RFC), an organic anion antiporter, that is the major route of folate transport to systemic tissues. The clinical characteristics of HFM and its treatment, based upon the thirty-seven known cases with the clinical syndrome, of which thirty have been verified by genotype, are presented. The ways in which PCFT and FRα might interact at the level of the choroid plexus such that each is required for folate transport from blood to cerebrospinal fluid are considered along with the different clinical presentations of HFM and CFD. [ABSTRACT FROM AUTHOR]

Background We describe a new method for simultaneous measurement of monoamine metabolites (3-O-methyldopa [3-OMD], 3-methoxy-4-hydroxyphenylethyleneglycol [MHPG], 5-hydroxyindoleacetic acid [5-HIAA], and homovanillic acid [HVA]) and 5-methyltetrahydrofolate (5-MTHF) and its use on cerebrospinal fluid (CSF) samples from pediatric patients. Methods Monoamine metabolites and 5-MTHF were measured by high-performance liquid chromatography with fluorescence detection. CSF samples were prospectively collected from children according to a standardized collection protocol in which the first 1-ml fraction was used for analysis. Results Monoamine metabolites and 5-MTHF were separated within 10 min. They showed linearity from the limit of detection to 1024 nmol/l. The limit of quantification of each metabolite was sufficiently low for the CSF sample assay. In 42 CSF samples after excluding cases with possibly altered neurotransmitter profiles, the concentrations of 3-OMD, MHPG, 5-HIAA, HVA, and 5-MTHF showed significant age dependence and their ranges were comparable with the reference values in the literature. The metabolite profiles of aromatic l -amino acid decarboxylase deficiency, Segawa disease, and folate receptor α defect by this method were compatible with those in the literature. Conclusions This method is a simple means of measuring CSF monoamine metabolites and 5-MTHF, and is especially useful for laboratories not equipped with electrochemical detectors. [ABSTRACT FROM AUTHOR]

Background Cerebral folate transporter deficiency caused by FOLR-1 mutations has been described in 2009. This condition is characterized by a 5MTHF level <5 nmol/l in the CSF, along with regression of acquisition in the second year of life, ataxia, and refractory myoclonic epilepsy. Oral or intravenous folinic acid (5-formyltetrahydrofolate) treatment has been shown to improve clinical status. Case presentation We present the cases of two sisters with cerebral folate transport deficiency caused by mutation in the folate receptor 1 (FOLR1) gene (MIM *136430). Following recommendations, we administered oral folinic acid at 5 mg/kg/day, resulting in some initial clinical improvement, yet severe epilepsy persisted. During treatment, cerebrospinal fluid (CSF) analysis revealed normal 5-methyltetrahydrofolate (5MTHF) levels (60.1 nmol/l; normal range: 53–182 nmol/l). Epilepsy proved difficult to control and the younger patient exhibited neurological regression. We then administered high-dose folinic acid intravenously over 3 days (6 mg/kg/day for 24 h, then 12 mg/kg/day for 48 h), which significantly improved clinical status and epilepsy. CSF analysis revealed high 5MTHF levels following intravenous infusion (180 nmol/l). Treatment continued with monthly intravenous administrations of 20–25 mg/kg folinic acid. At 2 years post-treatment, clinical improvement was confirmed. Conclusions This report illustrates that cerebral folate transporter deficiency caused by FOLR-1 mutations is a treatable condition and can potentially be cured by folinic acid treatment. As already reported, early effective treatment is known to improve outcomes in affected children. In our study, intravenous high-dose folinic acid infusions appeared to optimize clinical response. [ABSTRACT FROM AUTHOR]

Multiple factors such as genetic and extraneous causes (drugs, toxins, adverse psychological events) contribute to neuro-psychiatric conditions. In a subgroup of these disorders, systemic folate deficiency has been associated with macrocytic anemia and neuropsychiatric phenotypes. In some of these, despite normal systemic levels, folate transport to the brain is impaired in the so-called cerebral folate deficiency (CFD) syndromes presenting as developmental and psychiatric disorders. These include infantile-onset CFD syndrome, infantile autism with or without neurologic deficits, a spastic-ataxic syndrome and intractable epilepsy in young children expanding to refractory schizophrenia in adolescents, and finally treatment-resistant major depression in adults. Folate receptor alpha (FRα) autoimmunity with low CSF N 5 -methyl-tetrahydrofolate (MTHF) underlies most CFD syndromes, whereas FRα gene abnormalities and mitochondrial gene defects are rarely found. The age at which FRα antibodies of the blocking type emerge, determines the clinical phenotype. Infantile CFD syndrome and autism with neurological deficits tend to be characterized by elevated FRα antibody titers and low CSF MTHF. In contrast, in infantile autism and intractable schizophrenia, abnormal behavioral signs and symptoms may wax and wane with fluctuating FRα antibody titers over time accompanied by cycling changes in CSF folate, tetrahydrobiopterin (BH4) and neurotransmitter metabolites ranging between low and normal levels. We propose a hypothetical model explaining the pathogenesis of schizophrenia. Based on findings from clinical, genetic, spinal fluid and MRI spectroscopic studies, we discuss the neurochemical changes associated with these disorders, metabolic and regulatory pathways, synthesis and catabolism of neurotransmitters, and the impact of oxidative stress on the pathogenesis of these conditions. A diagnostic algorithm and therapeutic regimens using high dose folinic acid, corticosteroids and milk-free diet is presented which has proven to be beneficial in providing adequate folate to the brain and decreasing the FRα autoantibody titer in those positive for the antibody. [ABSTRACT FROM AUTHOR]

Epilepsy is part of the clinical phenotype in nearly 40% of children with mitochondrial disease, yet the underlying molecular mechanisms remain poorly understood. Energy depletion has been postulated as the cause of mitochondrial epilepsy, but if this were the case, then 100% of patients with mitochondrial disease would be expected to present with seizures. This review explores other potential disease mechanisms underlying mitochondrial epilepsy, including oxidative stress, impaired calcium homeostasis, immune dysfunction, and deficiency of vitamins, cofactors, reducing equivalents, and other metabolites. Different mechanisms are likely to predominate in different mitochondrial disorders, since mitochondrial function varies between neurons and astrocytes, between different types of neurons, and in different brain regions. Systematic studies in cell and animal models of mitochondrial disease are needed in order to develop effective therapies for mitochondrial epilepsy. This article is part of a Special Issue entitled “Status Epilepticus”. [ABSTRACT FROM AUTHOR]

Cerebral folate deficiency is defined as any neurological condition associated with low cerebrospinal fluid folate concentrations. It is becoming increasingly associated with several neurological diseases, either genetic or environmental. Treatment of cerebral folate deficiency by folate supplementation is generally effective, improving the neurological outcome of some patients. However, to treat cerebral folate deficiency, the proper choice of one of the available folate forms is essential. The distinct brain folate metabolism features compared with peripheral folate metabolic pathways strongly suggest the investigation of different folate forms, such as the biologically active folinic acid and 5-methyltetrahydrofolate, since they are efficiently transported to the brain. Regarding the oral doses of the different folate forms, despite the fact that there are some recommendations, there is no general consensus. Further investigation and designing clinical trials are advisable to elucidate these aspects. [ABSTRACT FROM AUTHOR]

Autism spectrum disorder (ASD) affects a significant number of individuals in the United States, with the prevalence continuing to grow. A significant proportion of individuals with ASD have comorbid medical conditions such as epilepsy. In fact, treatment-resistant epilepsy appears to have a higher prevalence in children with ASD than in children without ASD, suggesting that current antiepileptic treatments may be suboptimal in controlling seizures in many individuals with ASD. Many individuals with ASD also appear to have underlying metabolic conditions. Metabolic conditions such as mitochondrial disease and dysfunction and abnormalities in cerebral folate metabolism may affect a substantial number of children with ASD, while other metabolic conditions that have been associated with ASD such as disorders of creatine, cholesterol, pyridoxine, biotin, carnitine, γ-aminobutyric acid, purine, pyrimidine, and amino acid metabolism and urea cycle disorders have also been associated with ASD without the prevalence clearly known. Interestingly, all of these metabolic conditions have been associated with epilepsy in children with ASD. The identification and treatment of these disorders could improve the underlying metabolic derangements and potentially improve behavior and seizure frequency and/or severity in these individuals. This paper provides an overview of these metabolic disorders in the context of ASD and discusses their characteristics, diagnostic testing, and treatment with concentration on mitochondrial disorders. To this end, this paper aims to help optimize the diagnosis and treatment of children with ASD and epilepsy. This article is part of a Special Issue entitled “Autism and Epilepsy”. [ABSTRACT FROM AUTHOR]

Background: Hereditary folate malabsorption is a rare, autosomal recessive disorder of proton-coupled folate transporter deficiency resulting in folate deficiency. Left untreated, the condition can cause severe brain damage and megaloblastic anemia, leading to progressive psychomotor retardation, seizures and other neurological problems. Early diagnosis and treatment are crucial. No case has been documented yet in Mainland China until now. Methods: A Chinese girl affected by hereditary folate malabsorption was studied. The girl presented with recurrent megaloblastic anemia from the age of 7 months. Paroxysmal limbs trembling and seizures were presented from the age of three years. Intracranial calcification was noted by CT. At her age of 5 years, mental regression, lower-extremity weakness and sleeping problems were observed. Her plasma folate decreased to 4.49 nmol/L (normal control > 6.8 nmol/L). Plasma total homocysteine elevated to 28.11 μmol/L (normal control < 15 μmol/L). Folate and 5-methylterahydrofolate in cerebrospinal fluid were significantly decreased to undetectable level. Results: On SLC46A1 gene, a novel mutation, c.1A>T (M1L), and a reported mutation c.194-195insG (p.Cys66LeufsX99) were identified, supported the diagnosis of hereditary folate malabsorption. Each parent carries one of two mutations. Folinic calcium supplement resulted in rapid clinical improvement. She is currently 6 years old with normal development and routine blood features. Conclusion: Hereditary folate malabsorption is one of the few easily-treatable inherited metabolic diseases. Measurements of folate and 5-methyltetrahydrofolate in cerebrospinal fluid are keys for the diagnosis of the patients. [ABSTRACT FROM AUTHOR]

The authors discuss the study of patients having treatment-refractory depression for secondary and primary disorders of central nervous system (CNS) metabolism. They mention that it is not cost-prohibitive to include B12 and serum folate levels in the routine assessment of patients having treatment-resistant depression. They say that glycine is especially interesting as blood levels have revealed predictive value for response to conventional depressants.

Background Kearns-Sayre syndrome (KSS) is a mitochondrial DNA deletion syndrome that presents with profound cerebral folate deficiency and other features. Preliminary data support the notion that folinic acid therapy might be useful in the treatment of KSS patients. Our aim was to assess the clinical and neuroimaging outcomes of KSS patients receiving folinic acid therapy. Methods Patients: We recruited eight patients with diagnoses of KSS. Four cases were treated at 12 de Octubre Hospital, and the other two cases were treated at Sant Joan de D?u Hospital. Two patients refused to participate in the treatment protocol. Methods: Clinical, biochemical and neuroimaging data (magnetic resonance imaging or computed tomography scan) were collected in baseline conditions and at different time points after the initiation of therapy. Cerebrospinal fluid 5-methyltetrahydrofolate levels were analysed with HPLC and fluorescence detection. Large-scale mitochondrial DNA deletions were analysed by Southern blot. Treatment protocol: The follow-up periods ranged from one to eight years. Cases 1?4 received oral folinic acid at a dose of 1 mg/kg/day, and cases 6 and 8 received 3 mg/kg/day. Results No adverse effects of folinic acid treatment were observed. Cerebral 5-methyltetrahydrofolate deficiencies were observed in all cases in the baseline conditions. Moreover, all three patients who accepted lumbar puncture after folinic acid therapy exhibited complete recoveries of their decreased basal cerebrospinal fluid 5-methyltetrahydrofolate levels to normal values. Two cases neurologically improved after folinic therapy. Disease worsened in the other patients. Post-treatment neuroimaging was performed for the 6 cases that received folinic acid therapy. One patient exhibited improvements in white matter abnormalities. The remaining patients displayed progressions in subcortical cerebral white matter, the cerebellum and cerebral atrophy. Conclusions Four patients exhibited clinical and radiological progression of the disease following folinic acid treatment. Only one patient who was treated in an early stage of the disease exhibited both neurological and radiological improvements following elevated doses of folinic acid, and an additional patient experienced neurological improvement. Early treatment with highdose folinic acid therapy seems to be advisable for the treatment of KSS. Trial registration EudracT2007-00-6748-23. [ABSTRACT FROM AUTHOR]

Background Auto-antibodies against folate receptor alpha (FRα) at the choroid plexus that block N 5 -methyltetrahydrofolate (MTHF) transfer to the brain were identified in catatonic schizophrenia. Acoustic hallucinations disappeared following folinic acid treatment. Folate transport to the CNS prevents homocysteine accumulation and delivers one-carbon units for methyl-transfer reactions and synthesis of purines. The guanosine derivative tetrahydrobiopterin acts as common co-factor for the enzymes producing dopamine, serotonin and nitric oxide. Methods Our study selected patients with schizophrenia unresponsive to conventional treatment. Serum from these patients with normal plasma homocysteine, folate and vitamin B12 was tested for FR autoantibodies of the blocking type on serial samples each week. Spinal fluid was analyzed for MTHF and the metabolites of pterins, dopamine and serotonin. The clinical response to folinic acid treatment was evaluated. Results Fifteen of 18 patients (83.3%) had positive serum FR auto-antibodies compared to only 1 in 30 controls (3.3%) (χ 2 = 21.6; p < 0.0001). FRα antibody titers in patients fluctuated over time varying between negative and high titers, modulating folate flux to the CNS, which explained low CSF folate values in 6 and normal values in 7 patients. The mean ± SD for CSF MTHF was diminished compared to previously established controls (t-test: 3.90; p = 0.0002). A positive linear correlation existed between CSF MTHF and biopterin levels. CSF dopamine and serotonin metabolites were low or in the lower normal range. Administration of folinic acid (0.3–1 mg/kg/day) to 7 participating patients during at least six months resulted in clinical improvement. Conclusion Assessment of FR auto-antibodies in serum is recommended for schizophrenic patients. Clinical negative or positive symptoms are speculated to be influenced by the level and evolution of FRα antibody titers which determine folate flux to the brain with up- or down-regulation of brain folate intermediates linked to metabolic processes affecting homocysteine levels, synthesis of tetrahydrobiopterin and neurotransmitters. Folinic acid intervention appears to stabilize the disease process. [ABSTRACT FROM AUTHOR]

(1) Background: The genetic etiology of most patients with cerebral folate deficiency (CFD) remains poorly understood. KDM6B variants were reported to cause neurodevelopmental diseases; however, the association between KDM6B and CFD is unknown; (2) Methods: Exome sequencing (ES) was performed on 48 isolated CFD cases. The effect of KDM6B variants on KDM6B protein expression, Histone H3 lysine 27 epigenetic modification and FOLR1 expression were examined in vitro. For each patient, serum FOLR1 autoantibodies were measured; (3) Results: Six KDM6B variants were identified in five CFD patients, which accounts for 10% of our CFD cohort cases. Functional experiments indicated that these KDM6B variants decreased the amount of KDM6B protein, which resulted in elevated H3K27me2, lower H3K27Ac and decreased FOLR1 protein concentrations. In addition, FOLR1 autoantibodies have been identified in serum; (4) Conclusion: Our study raises the possibility that KDM6B may be a novel CFD candidate gene in humans. Variants in KDM6B could downregulate FOLR1 gene expression, and might also predispose carriers to the development of FOLR1 autoantibodies.