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.

Folinic acid treatment for schizophrenia associated with folate receptor autoantibodies.

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 (0.3-1mg/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.

The basis for folinic acid treatment in neuro-psychiatric disorders.

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.

A common mutation (epsilon1267delG) in congenital myasthenic patients of Gypsy ethnic origin.

OBJECTIVE: Mutation analysis of the acetylcholine receptor (AChR) epsilon subunit gene in patients with sporadic or autosomal recessive congenital myasthenic syndromes (CMS). BACKGROUND: The nicotinic AChR of skeletal muscle is a neurotransmitter-gated ion channel that mediates synaptic transmission at the vertebrate neuromuscular junction. Mutations in its gene may cause congenital myasthenic syndromes. A recently described mutation in exon 12 of the AChR epsilon subunit (epsilon1267delG) disrupts the cytoplasmic loop and the fourth transmembrane region (M4) of the AChR epsilon subunit. METHODS: Forty-three CMS patients from 35 nonrelated families were clinically classified as sporadic cases of CMS (group III according to European Neuromuscular Centre consensus) and were analyzed for epsilon1267delG by PCR amplification and sequence analysis. RESULTS: The authors report the complete genomic sequence and organization of the gene coding for the epsilon subunit of the human AChR (accession number AF105999). Homozygous epsilon1267delG was identified in 13 CMS patients from 11 independent families. All epsilon1267delG families were of Gypsy or southeastern European origin. Genotype analysis indicated that they derive from a common ancestor (founder) causing CMS in the southeastern European Gypsy population. Phenotype analysis revealed a uniform pattern of clinical features including bilateral ptosis and mild to moderate fatigable weakness of ocular, facial, bulbar, and limb muscles. CONCLUSIONS: The mutation epsilon1267delG might be frequent in European congenital myasthenic syndrome patients of Gypsy ethnic origin. In general, patients (epsilon1267delG) were characterized by the onset of symptoms in early infancy, the presence of ophthalmoparesis, positive response to anticholinesterase treatment, and the benign natural course of the disease.

Phenotypic variation of a novel nonsense mutation in the P0 intracellular domain.

Mutations in the gene for the peripheral myelin protein zero (P0, MPZ) cause type 1B of Charcot-Marie-Tooth sensorimotor neuropathy (CMT1B). Here we report a German family with a novel heterozygous P0 nonsense mutation (G206X) that supposedly removes four-fifths of the amino acid residues constituting the P0 intracellular domain. The 12-year-old propositus had childhood-onset CMT1B associated with bilateral pes cavus, moderate lower limb weakness, and mildly reduced sensory qualities in the distal legs. The electrophysiology was consistent with a demyelinating neuropathy. He inherited the mutation from his mother who had no complaints but slight pes cavus deformity and slow nerve conduction velocities (NCV). Conclusively, truncating mutations within the P0 intracellular domain do not necessarily cause a severe phenotype such as Dejerine-Sottas syndrome (DSS) or congenital hypomyelinating neuropathy (CHN), but can result in mild or moderate CMT1B with intrafamilial clinical variability.

Encephalitis related to primary varicella-zoster virus infection in immunocompetent children.

INTRODUCTION: Encephalitis is a rare complication of primary varicella-zoster virus (VZV) infection in immunocompetent children. METHODS: The clinical and laboratory findings of two girls with VZV-related encephalitis are reported. RESULTS: Both children presented with focal epileptic seizures, corresponding to cortical/subcortical as well as white matter lesions. The first showed a typical vesicular skin rash. She was easily diagnosed and made a rapid recovery during acyclovir and steroid treatment. In the second girl, a preceding measles-mumps-rubella virus vaccination and the absence of skin vesicles were misleading with respect to the diagnosis, which was finally proven by IgG seroconversion and intrathecal synthesis of IgG antibodies to VZV. She developed left parieto-occipital tissue necrosis and recovered only transiently during initial acyclovir/steroid treatment. Eight weeks after onset, progressive white matter demyelination and the occurrence of erythema nodosum in the lower limbs necessitated a second 4-month course of oral steroids. The VZV PCR from cerebrospinal fluid was negative in both children. CONCLUSIONS: Primary VZV infection may cause severe encephalitis that may occur without skin vesicles and lead to a chronic course with systemic vasculitis. The coincidence of vaccination and neurologic diseases offers no proof per se of a causal relationship.

X-linked dominant Charcot-Marie-Tooth neuropathy: clinical, electrophysiological, and morphological phenotype in four families with different connexin32 mutations(1).

The sensorimotor neuropathy of the Charcot-Marie-Tooth type (CMT) is the most common hereditary disorder of the peripheral nervous system. The X-linked dominant form of CMT (CMTX) is associated with mutations in the gene for the gap junction protein connexin32. We examined four CMTX pedigrees two of which had potentially novel mutations in the only coding exon of connexin32. One previously unreported missense mutation, Ala39Val, was found in a family displaying a CMT phenotype with additional upper limb postural tremor reminiscent of a Roussy-Lévy syndrome. A novel single base insertion, 679insT, is among the first mutations found in the fourth transmembrane domain of connexin32. Frameshift and premature stop of translation are supposed to result in a non-functional carboxy-terminus. Two further families had the known missense mutations Arg15Trp and Arg22Gln. Several female carriers were found normal on clinical presentation, however, the genotype was paralleled by decreased nerve conduction velocities (NCV) and slowed central conduction of brain stem auditory evoked responses (BAER). Median motor NCVs showed mild (in women) to intermediate (in males) reduction, indicating a peripheral neuropathy with a predominating axonal component. Nerve biopsy findings were consistent with the electrophysiological data showing a marked loss of large myelinated fibres and clusters of regenerating axons. Electron microscopy revealed various alterations of the axoglial attachment zone. This suggests defective axon-Schwann cell interactions which may induce the axonopathy in CMTX.

Cerebral hyperperfusion following episodes of bradycardia in the preterm infant.

The alterations in cerebral hemodynamics during and following 39 episodes with bradycardia of different severity have been studied by analysis of Doppler flow velocity waveforms amongst 16 stable preterm infants (range of conceptional age at the time of study 33-39 weeks; weight 1730-2820 g). Each episode with bradycardia has been classified as mild on seven occasions (heart rate between 100-120 beats/min), moderate on 15 occasions (80-100), or severe on 17 occasions (heart rate below 80) Depending on the severity of the bradycardia, the time-averaged mean flow velocity (V) could decrease by 80% below the preexistent baseline value and the end-diastolic velocity (D) dropped towards the zero line, whereas peak systolic velocities did not change The magnitude of the percentage decrease of V correlated positively with the severity of bradycardia, indicating a progressive decline of cerebral blood flow (CBF). Following bradycardia, V could increase up to 75% above the preexistent baseline value. Simultaneously, an increase of mean arterial blood pressure and D could be documented. Peak systolic velocities remained unaltered. The magnitude of the percentage increase of V following bradycardia depended both on the severity of bradycardia as well as on the drop in transcutaneous oxygen during the preceding bradycardia. Interpretation of these findings suggested that the transient cerebral hyperperfusion following bradycardia compensates for the hypoxic-ischemic episode, sustained during the preceding epoch of apnea and bradycardia.

The influence of blood transfusion on brain blood flow autoregulation among stable preterm infants.

Prior to and 24 h following blood transfusion serial determinations of both cerebral artery flow velocity waveforms and mean arterial blood pressure have been used to reconstruct the autoregulatory curve and its upper blood pressure limit among five stable preterm infants. Prior to transfusion the autoregulatory range of cerebral blood flow (CBF) was narrow due to a relatively low-set upper blood pressure limit. At 24 h after transfusion each individual has been re-examined. Following correction of anemia both a significant reduction of CBF velocities as well as a concomitant rise of the Pulsatility Index (PI) occurred over the entire range of blood pressures indicating a reduction of CBF after transfusion. In addition a right-sided shift of the upper limit towards higher mean blood pressures occurred after transfusion and resulted in an extension of the autoregulatory plateau of CBF. These favourable effects of blood transfusion ameliorating autoregulation of brain blood flow particularly at higher blood pressures might well bear important therapeutic perspectives in our effort to prevent intracranial haemorrhage among sick preterm infants.

Upper limits of brain blood flow autoregulation in stable infants of various conceptional age.

In healthy adults cerebral blood flow is autoregulated and kept constant over a wide range of mean arterial blood pressures (MAP) between 60 and 150 mmHg. In 27 stable infants with different conceptional ages ranging from 33 to 50 weeks, Doppler measurements of mean flow velocity at the anterior cerebral artery have been recorded simultaneously with mean arterial blood pressures (MAP) during a period of 6 h. The range of autoregulation and its upper limit could thus be determined. The upper limit was found to increase with advancing age. In the infants with conceptional ages between 33 and 35 weeks, the upper limit of autoregulation varied between 45 and 60 mmHg, while the upper limit shifted to a MAP of 100 mmHg at 47 weeks conceptional age. A significant positive linear relationship existed between the upper limit of autoregulation and conceptional age.

The influence of behavioural states on cerebral blood flow velocity patterns in stable preterm infants.

Previous Doppler ultrasound studies assessing cerebral blood flow velocities in the anterior cerebral artery (ACA) among healthy term and preterm infants, showed a widespread range for the calculated flow indices. However, only one of these studies accounted for the infant's behavioural state. In the present study a stable pattern of the cerebral blood flow velocity tracings and of the Pulsatility Index (PI) was observed during state 1, whereas marked fluctuations in cerebral blood flow velocity and PI were found during state 4 or active wakefulness. During state 2, minor variations of cerebral blood flow velocity and PI occurred though tended to be less pronounced than during active wakefulness. Thus at the time of Doppler assessment the cerebral blood flow velocity pattern and its variability will be better understood by taking into account the behavioural state of the infant.

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.

Mitochondrial complex I encephalomyopathy and cerebral 5-methyltetrahydrofolate deficiency.

Folate transport to the brain depends on ATP-driven folate receptor-mediated transport across choroid plexus epithelial cells. Failure of ATP production in Kearns-Sayre syndrome syndrome provides one explanation for the finding of low spinal fluid (CSF) 5-methyltetrahydrofolate (5MTHF) levels in this condition. Therefore, we suspect the presence of reduced folate transport across the blood-spinal fluid barrier in other mitochondrial encephalopathies. In the present patient with mitochondrial complex I encephalomyopathy a low 5-methyltetrahydrofolate level was found in the CSF. Serum folate receptor autoantibodies were negative and could not explain the low spinal fluid folate levels. The epileptic seizures did not respond to primidone monotherapy, but addition of ubiquinone-10 and radical scavengers reduced seizure frequency. Add-on treatment with folinic acid led to partial clinical improvement including full control of epilepsy, followed by marked recovery from demyelination of the brainstem, thalamus, basal ganglia and white matter. Cerebral folate deficiency is not only present in Kearns-Sayre syndrome but may also be secondary to the failure of mitochondrial ATP production in other mitochondrial encephalopathies. Treatment with folinic acid in addition to supplementation with radical scavengers and cofactors of deficient respiratory enzymes can result in partial clinical improvement and reversal of abnormal myelination patterns on neuro-imaging.

Folate receptor autoantibodies and spinal fluid 5-methyltetrahydrofolate deficiency in Rett syndrome.

Rett syndrome was associated with low cerebrospinal fluid (CSF) 5-methyltetrahydrofolate (5MTHF) in 42-50% of European patients whereas approximately 93% of the patients from North-America had a normal CSF 5MTHF status. We determined the CSF folate status in Rett patients living in North- and South-Western Europe and measured serum folate receptor (FR) autoantibodies of the blocking type to explain the reduced folate transport across the choroid plexus. Irrespective of their MECP2 genotype and despite normal plasma folate values, 14 of 33 Rett patients (42%) had low CSF folate levels. Blocking FR autoantibodies were found in 8 of the Rett patients (24%), 6 of whom had low CSF folate levels. FR autoimmunity was primarily found within the group of Rett patients with low CSF folate status with a higher incidence in North-Western Europe. In Rett patients from North-America 74 of 76 girls had higher folate values in both serum and CSF than European patients. The food folate fortification in North-America may account for the higher folate levels and may prevent CFD in these Rett patients. FR autoimmunity occurred predominantly in Rett patients from North-Western Europe and may contribute to cerebral folate deficiency (CFD).

White-matter disease in 18q deletion (18q-) syndrome: magnetic resonance spectroscopy indicates demyelination or increased myelin turnover rather than dysmyelination.

Proton magnetic resonance spectroscopic data ((1)H-MR spectroscopy) of patients with 18q deletion syndrome have not yet been reported. (1)H-MR spectroscopy, performed in an affected 2-year-old girl with markedly delayed neuromotor development and typical supratentorial white-matter disease (WMD), showed an increase of choline and alpha-glutamate concentrations. Eight months later, simultaneously with clinical improvement, alpha-glutamate had normalised whereas choline remained slightly increased. Active demyelination or increased myelin turnover might contribute to the hitherto unexplained WMD of this rare disorder.

Cerebral folate deficiency with developmental delay, autism, and response to folinic acid.

The authors describe a 6-year-old girl with developmental delay, psychomotor regression, seizures, mental retardation, and autistic features associated with low CSF levels of 5-methyltetrahydrofolate, the biologically active form of folates in CSF and blood. Folate and B12 levels were normal in peripheral tissues, suggesting cerebral folate deficiency. Treatment with folinic acid corrected CSF abnormalities and improved motor skills.

Persistent hyperplastic primary vitreous: MRI.

Persistent hyperplastic primary vitreous (PHPV), a developmental cause of leukocoria, is due to incomplete regression of the fetal blood supply to the eye. We report the MRI features of PHPV of the dorsal type to facilitate differential diagnosis from other causes of leukocoria, namely retinoblastoma, which may have major therapeutic consequences.

[Suprasellar space-occupying lesion as initial manifestation of tuberculosis in childhood]. / Supraselläre Raumforderung als Erstmanifestation einer Tuberkulose im Kindesalter.

Three days after having sustained a mild trauma to the head a seven-year-old boy developed seizure-like rotatory vertigo. Computed tomography, magnetic resonance imaging and cerebral angiography demonstrated a suprasellar space-occupying lesion. Pulmonary tuberculosis was discovered in subsequent diagnostic work-up. Cerebrospinal fluid examination was unremarkable except for immunological tests (tuberculostearic acid) which pointed to central nervous system (CNS) involvement so that a tuberculoma was suspected. The lesion decreased in size on tuberculostatic treatment (200 mg/d isoniazid, 200 mg/d rifampicin, two times 250 mg/d pyrazinamide). In the next 12 months there merely persisted a mild abnormality of the blood-brain barrier with a little contrast-medium uptake, which regressed in the following 6 months. The differential diagnosis between CNS tuberculosis and brain tumour or pyogenic abscess can be difficult in children if there are no pulmonary signs and/or the cerebrospinal fluid is normal.

Defective regulation of cerebral oxygen transport after severe birth asphyxia.

Cerebral artery Doppler ultrasonography was used to study the cerebral blood-flow velocity and cerebral oxygen transport of infants requiring a blood transfusion to correct anaemia. Mean flow velocity, pulsatility index and haemoglobin concentration were determined before and after transfusion. 11 stable preterm infants demonstrated an inverse relationship between haemoglobin concentration (or estimated arterial oxygen content) and mean flow velocity, indicating the presence of a homeostatic mechanism keeping brain oxygen transport within certain limits. Three infants with severe post-asphyxial encepalopathy had relatively high mean flow velocities and low pulsatility indices both before and after transfusion. There were no circulatory adjustments in response to an increase in haemoglobin concentration. Thus severe asphyxia at birth disrupted the homeostatic mechanism responsible for keeping brain oxygen transport constant. These findings stress the importance of close monitoring of arterial oxygen content, particularly for infants with severe post-asphyxial encephalopathy.