[Recommendations for aminoacids chromatography analysis]. / Recommandations concernant l'analyse de la chromatographie des acides aminés.

Biochemical diagnosis of hereditary metabolic diseases requires the detection and simultaneous identification of a large number of compounds, hence the interest in metabolic profiles. Amino acid chromatography allows the identification and quantification of more than forty compounds. As part of the accreditation process for medical biology examinations according to standard NF EN ISO 15189, the group from SFEIM recommends an approach to accredit amino acid chromatography. Validation parameters and recommendations are discussed in this specific framework.

Confirmation of neurometabolic diagnoses using age-dependent cerebrospinal fluid metabolomic profiles.

Timely diagnosis is essential for patients with neurometabolic disorders to enable targeted treatment. Next-Generation Metabolic Screening (NGMS) allows for simultaneous screening of multiple diseases and yields a holistic view of disturbed metabolic pathways. We applied this technique to define a cerebrospinal fluid (CSF) reference metabolome and validated our approach with patients with known neurometabolic disorders. Samples were measured using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry followed by (un)targeted analysis. For the reference metabolome, CSF samples from patients with normal general chemistry results and no neurometabolic diagnosis were selected and grouped based on sex and age (0-2/2-5/5-10/10-15 years). We checked the levels of known biomarkers in CSF from seven patients with five different neurometabolic disorders to confirm the suitability of our method for diagnosis. Untargeted analysis of 87 control CSF samples yielded 8036 features for semiquantitative analysis. No sex differences were found, but 1782 features (22%) were different between age groups (q < 0.05). We identified 206 diagnostic metabolites in targeted analysis. In a subset of 20 high-intensity metabolites and 10 biomarkers, 17 (57%) were age-dependent. For each neurometabolic patient, ≥1 specific biomarker(s) could be identified in CSF, thus confirming the diagnosis. In two cases, age-matching was essential for correct interpretation of the metabolomic profile. In conclusion, NGMS in CSF is a powerful tool in defining a diagnosis for neurometabolic disorders. Using our database with many (age-dependent) features in CSF, our untargeted approach will facilitate biomarker discovery and further understanding of mechanisms of neurometabolic disorders.

Targeted cerebrospinal fluid analysis for inborn errors of metabolism on an LC-MS/MS analysis platform.

BACKGROUND: Laboratory investigations of cerebrospinal fluid (CSF) are essential when suspecting an inborn error of metabolism (IEM) involving neurological features. Available tests are currently performed on different analytical platforms, requiring a large sample volume and long turnaround time, which often delays timely diagnosis. Therefore, it would be preferable to have an "one-instrument" targeted multi-metabolite approach. METHOD: A liquid chromatography-tandem mass spectrometry (LC-MS/MS) platform, based on two different methods for analysing 38 metabolites using positive and negative electrospray ionisation modes, was established. To allow for platform extension, both methods were designed to use the same CSF sample preparation procedure and to be run on the same separation column (ACE C18-PFP). RESULTS: Assessment of the LC-MS/MS platform methods was first made by analytical validation, followed by the establishment of literature-based CSF cut-off values and reference ranges, and by the measurement of available samples obtained from patients with confirmed diagnoses of aromatic l-amino acid decarboxylase deficiency, guanidinoacetate methyltransferase deficiency, ornithine aminotransferase deficiency, cerebral folate deficiency and methylenetetrahydrofolate reductase deficiency. CONCLUSION: An extendable targeted LC-MS/MS platform was developed for the analysis of multiple metabolites in CSF, thereby distinguishing samples from patients with IEM from non-IEM samples. Reference concentrations for several biomarkers in CSF are provided for the first time. By measurement on a single analytical platform, less sample volume is required (200 µL), diagnostic results are obtained faster, and preanalytical issues are reduced. SYNOPSIS: LC-MS/MS platform for CSF analysis consisting of two differentially designed methods.

Direct-infusion based metabolomics unveils biochemical profiles of inborn errors of metabolism in cerebrospinal fluid.

BACKGROUND: For inborn errors of metabolism (IEM), metabolomics is performed for three main purposes: 1) development of next generation metabolic screening platforms, 2) identification of new biomarkers in predefined patient cohorts and 3) for identification of new IEM. To date, plasma, urine and dried blood spots are used. We anticipate that cerebrospinal fluid (CSF) holds additional - valuable - information, especially for IEM with neurological involvement. To expand metabolomics to CSF, we here tested whether direct-infusion high-resolution mass spectrometry (DI-HRMS) based non-quantitative metabolomics could correctly capture the biochemical profile of patients with an IEM in CSF. METHODS: Eleven patient samples, harboring eight different IEM, and thirty control samples were analyzed using DI-HRMS. First we assessed whether the biochemical profile of the control samples represented the expected profile in CSF. Next, each patient sample was assigned a 'most probable diagnosis' by an investigator blinded for the known diagnoses of the patients. RESULTS: the biochemical profile identified using DI-HRMS in CSF samples resembled the known profile, with - among others - the highest median intensities for mass peaks annotated with glucose, lactic acid, citric acid and glutamine. Subsequent analysis of patient CSF profiles resulted in correct 'most probable diagnoses' for all eleven patients, including non-ketotic hyperglycinaemia, propionic aciduria, purine nucleoside phosphorylase deficiency, argininosuccinic aciduria, tyrosinaemia type I, hyperphenylalaninemia and hypermethioninaemia. CONCLUSION: We here demonstrate that DI-HRMS based non-quantitative metabolomics accurately captures the biochemical profile of this set of patients in CSF, opening new ways for using metabolomics in CSF in the metabolic diagnostic laboratory.

Gamma-aminobutyric acid levels in cerebrospinal fluid in neuropaediatric disorders.

AIM: Gamma-aminobutyric acid (GABA) is a major modulator in brain maturation and its role in many different neurodevelopmental disorders has been widely reported. Although the involvement of GABA in different disorders has been related to its regulatory function as an inhibitory neurotransmitter in the mature brain, co-transmitter, and signalling molecule, little is known about its role as a clinical biomarker in neuropaediatric disorders. The aim of this study is to report the cerebrospinal fluid (CSF) free-GABA concentrations in a large cohort of patients (n=85) with different neurological disorders. METHOD: GABA was measured in the CSF of neuropaediatric patients using capillary electrophoresis with laser-induced fluorescence detection. Other neurotransmitters (amino acids and monoamines) were also analysed. RESULTS: GABA concentrations in CSF were abnormal, with a greater frequency (44%) than monoamines (20%) in neuropaediatric patients compared with our reference values. Although we included a few patients with inborn errors of metabolism, GABA levels in CSF were more frequently abnormal in metabolic disorders than in other nosological groups. INTERPRETATION: Our work suggests further research into brain GABAergic status in neuropaediatric disorders, which could also lead to new therapeutic strategies. WHAT THIS PAPER ADDS: Homeostasis of GABA seems more vulnerable than that of monoamines in the developing brain. The highest GABA levels are found in the primary GABA neurotransmitter disorder SSADH deficiency. GABA alterations are not specific for any clinical or neuroimaging presentation.

Sepiapterin reductase deficiency: Report of 5 new cases.

BACKGROUND: Sepiapterin reductase deficiency is a rare, under-recognized, autosomal recessively inherited disorder of neurotransmitter metabolism. CASE REPORT: Five new patients from 3 unrelated Saudi consanguineous families are reported. Symptoms began at 6 months, with delay to diagnosis averaging 8 years. All 5 patients presented with severe symptoms including axial hypotonia, dystonia, and cognitive impairment, associated with hyper-reflexia (4 patients), spasticity (4 patients), bulbar dysfunction (4 patients), and oculogyric crisis (2 patients) with diurnal fluctuation and sleep benefit. Cerebrospinal fluid neurotransmitters analysis showed a typical pattern with increased sepiapterin and increased 7,8-dihydrobiopterin. Analysis of the SPR gene identified 3 novel mutations: c.1A > G, c.370T > C, and c.527C > T. Patient one, with early diagnosis, is currently developing within the normal range. The 4 other patients showed significant improvement in their motor function, but only mild improvement in their cognitive dysfunction. CONCLUSION: Our cases illustrate the difficulties in the diagnosis of sepiapterin reductase deficiency in infancy, and the importance of early recognition and management.

Clinical Use of CSF Neurotransmitters.

BACKGROUND: Cerebrospinal fluid neurotransmitter collection, analysis, and follow-up are integral to the diagnosis and management of multiple inborn metabolic errors, some of which require prompt identification and intervention to improve outcome. Cerebrospinal fluid pterins and monoamine metabolites are diagnostic in a range of primary neurotransmitter disorders, including disorders of biogenic amine synthesis, metabolism, and transport. RELEVANT DISORDERS: Recently described mutations of the human dopamine transporter are associated with an elevated cerebrospinal fluid homovanillic acid:hydroxyindoleacetic acid ratio. Disorders of pyridoxine metabolism are also detectable via cerebrospinal fluid quantification of bioamines, amino acids, and pyridoxal-5-phosphate levels. Cerebrospinal fluid amino acids are diagnostic in disorders of gamma aminobutyric acid, glycine, and serine metabolism. A wide range of acquired and genetic disorders has also been associated with secondary alterations in cerebrospinal fluid levels of monoamine metabolites, glycine, and neopterin. CONCLUSIONS: Lumbar puncture is required to detect abnormal cerebrospinal fluid metabolites in a significant proportion of these disorders, including treatable entities such as dopa-responsive deficiencies of guanosine-5'-triphosphate cyclohydrolase I (Segawa disease), sepiapterin reductase, and tyrosine hydroxylase.

Allelic variations of glut-1 deficiency syndrome: the chinese experience.

Glucose transporter type 1 deficiency syndrome is characterized by infantile onset seizures, development delay, movement disorders, and acquired microcephaly. The phenotype includes allelic variants such as intermittent ataxia, choreoathetosis, dystonia, and alternating hemiplegia of childhood with or without epilepsy. Dystonias involve allelic variants of glucose transporter type 1 deficiency syndrome. Three Chinese patients presented with paroxysmal behavioral disturbance, weakness, ataxia (especially after fasting), and exercise intolerance. Electroencephalogram findings did not correlate with clinical manifestations. Cranial magnetic resonance imaging produced normal results or mild hypomyelination. Hypoglycorrhachia was evident in all cases. Cerebrospinal fluid glucose ranged from 1.63-2.45 mmol/L. Erythrocyte 3-O-methyl-d-glucose uptake was decreased to 58% in patient 1. Three SLC2A1 disease-causing mutations (761delA, P383H, and R400C) were observed. No patient tolerated ketogenic diets. Two patients responded to frequent meals with snacks. Cerebrospinal fluid evaluation constitutes the diagnostic testing permitting early treatment of glucose transporter type 1 deficiency syndrome. Early diagnosis and treatment improve prognoses.

[Amino acids in cerebrospinal fluid and plasma: its usefulness in the study of neuropaediatric diseases]. / Aminoacidos en liquido cefalorraquideo y plasma: utilidad en el estudio de las enfermedades neuropediatricas.

INTRODUCTION: Studying the amino acids in cerebrospinal fluid (CSF) is essential in the diagnosis of some neurological diseases and is an important aid in the diagnosis of others. No research has been published in the literature to prove the physiological relationship between the values of amino acids in CSF and plasma in the paediatric population. AIM: To define a set of ratios for amino acids in plasma and CSF in the paediatric population that can be used in daily clinical practice. PATIENTS AND METHODS: The aminograms in plasma and CSF of 105 patients with ages between 0 and 12 months were collected and analysed retrospectively. Aminograms with amino acid values that are considered to be normal according to the reference values of our laboratory were included in the sample. The quantitative analysis of amino acids was performed using high-resolution liquid chromatography and statistical analysis with the software application SPSS 19.0. RESULTS: The mean values, range and standard deviation of the amino acid concentrations in plasma and CSF, together with the CSF/plasma ratios, are reported. Significant correlations were found from 0.6 onwards between different neutral amino acids, above all in those with smaller molecular weights (Thr, Ser, Gly and Ala). CONCLUSIONS: The existence of significant correlations between the different neutral amino acids supports the idea that they share the same transporters in the blood-brain barrier. Standardising the amino acid ratios will make it possible to increase sensitivity in the detection of pathological values in plasma and CSF, to further knowledge of the pathophysiology of neurological diseases and perhaps to describe new aminoacidopathies.

Two Greek siblings with sepiapterin reductase deficiency.

BACKGROUND: Sepiapterin reductase (SR) deficiency is a rare inherited disorder of neurotransmitter metabolism; less than 25 cases have been described in the literature so far. METHODS: We describe the clinical history and extensive cerebrospinal fluid (CSF) and urine examination of two Greek siblings with the diagnosis of SR deficiency. The diagnosis was confirmed by enzyme activity measurement in cultured fibroblasts and by mutation analysis. RESULTS: Both patients suffered from a progressive and complex L-dopa responsive movement disorder. Very low concentrations of the neurotransmitter metabolites homovanillic acid (HVA), 5-hydroxyindolacetic acid (5-HIAA) and 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) were observed in CSF. CSF neopterin and biopterin concentrations were abnormal in one case only, whereas in both cases sepiapterin concentrations were abnormally high and 5-hydroxytryptophan was undetectable. Urine concentrations of HVA, 5-HIAA and vanillyl mandelic acid (VMA) were decreased in both cases. Both patients had no detectable SR enzyme activity in primary dermal fibroblasts, and upon analysis of genomic DNA revealed the same homozygous point mutation introducing a premature stop codon into the reading frame of the SPR gene (mutant allele K251X). CONCLUSIONS: Our cases illustrate that, apart from HVA and 5-HIAA analysis, the specific quantification of sepiapterin in CSF, rather than neopterin and biopterin alone, is crucial to the final diagnosis of SR deficiency. In addition, urinary concentrations of neurotransmitter metabolites may be abnormal in SR deficiency and may provide an initial indication of SR deficiency before CSF analysis is performed. The known, impressive beneficial response of SR deficient patients to treatment with L-dopa, is illustrated again in our cases.

[Contribution of CSF analysis to the diagnosis of inborn errors of metabolism in adult patients]. / Apport de l'analyse du liquide cérébrospinal pour le diagnostic des maladies métaboliques héréditaires.

The diagnosis of certain metabolic diseases is problematic because it cannot be achieved with conventional blood and urine analyses but requires cerebrospinal fluid (CSF) study. CSF analysis is essential for the diagnosis of neurotransmitter metabolic disorders (synthesis defects of biogenic monoamines, non ketotic hyperglycinemia and homocarsinosis), defects of specific transporters (glucose cerebral transporter (Glut1) deficiency and cerebral folate deficiency) and is of help for the diagnosis of disorders of cerebral energy metabolism (respiratory chain disorders and pyruvate dehydrogenase deficiency). Our goal is to give an outline of hereditary metabolic diseases whose diagnosis is based on CSF analysis. We will detail late onset clinical forms which may be first seen in an adult neurology department.

[Contribution of in vitro NMR spectroscopy to metabolic and neurodegenerative disorders]. / Apports de la spectroscopie par résonance magnétique nucléaire des fluides dans l'étude de maladies métaboliques et neurodégénératives.

In vitro Nuclear Magnetic Resonance (NMR) spectroscopy is a validated biochemical tool for metabolic analyses of human body fluids and diagnosis of inborn errors of metabolism in children and adults. The technique is of special interest because it requires minimal sample preparation, it can detect simultaneously compounds of different nature and it offers structural information on the metabolites present in body fluids. In the last decade, in vitro NMR spectroscopy contributed to the identification of new inborn errors of metabolism, some of which are amenable to therapeutic intervention. Standardized analyses of body fluids, especially cerebrospinal fluid, are therefore indicated in patients affected with neurodegenerative disorders of unknown etiologies, for which extensive metabolic and genetic screening failed to identify the primary defect. In addition, the use of multivariate statistical analyses allows the comparison of the whole metabolic profile between patients with a given neurodegenerative disorder and controls. This so-called metabonomic approach yields promises for the discovery of biomarkers that can help detecting disease onset and progression, as well as evaluating therapeutic efficacy. Finally, the combination of in vitro NMR spectroscopy with genetic analytical tools may constitute a successful pathophysiological approach to investigate neurological disorders of unknown etiology.

[Usefulness of analysis of cerebrospinal fluid for the diagnosis of neurotransmitters and pterin defects and glucose and folate transport deficiencies across blood brain barrier]. / Utilidad del análisis del líquido cefalorraquídeo para el estudio de las deficiencias del metabolismo de neurotransmisores y pterinas y del transporte de glucosa y folato a través de la barrera hematoencefálica.

BACKGROUND AND OBJECTIVE: In the last few years, it has been described inborn errors of neurotransmitter and pterin metabolism and defects in folate and glucose transport across blood brain barrier. All these defects are classified as rare diseases and needs cerebrospinal fluid (CSF) sample analysis for diagnosis. Our aim was to evaluate the results of the application of a CSF analysis protocol in a pediatric population from Spain and Portugal presenting with neurological disorders of unknown origin. PATIENTS AND METHOD: We studied CSF samples from and 283 patients with neurological disorders of unknown origin and 127 controls. Neurotransmitters were analysed by HPLC with electrochemical detection, and pterins and 5-methyltetrahydrofolate were determined by HPLC with fluorescence detection. RESULTS: We diagnosed 3 patients with tyrosine hidroxylase deficiency, 2 with dopa responsive dystonia, 14 with GTP-ciclohydrolase deficiency, 2 with glucose transport deficiency and 43 with cerebral folate deficiency. CONCLUSIONS: This study allowed us to diagnose new patients, and more importantly, the establishment in all of them of a pharmacological or nutritional treatment. The most frequent defect found was CSF 5-methyltetrahydrofolate deficiency, which was present in different groups of patients.

Utilidad del análisis del líquido cefalorraquídeo para el estudio de las deficiencias del metabolismo de neurotransmisores y pterinas y del transporte de glucosa y folato a través de la barrera hematoencefálica / Usefulness of analysis of cerebrospinal fluid for the diagnosis of neurotransmitters and pterin defects and glucose and folate transport deficiencies across blood brain barrier

Fundamento y objetivo: En la última década se ha descrito diferentes errores congénitos del metabolismo de los neurotransmisores (NT), en especial de las vías dopaminérgica y serotoninérgica y de las pterinas. También se ha descrito defectos primarios en el transporte de glucosa y 5-metiltetrahidrofolato (5-MTHF) a través de la barrera hematoencefálica, todos ellos enfermedades raras para cuyo diagnóstico es necesario el estudio en líquido cefalorraquídeo (LCR). Nuestro objetivo ha sido evaluar los resultados de la aplicación de un protocolo de análisis de LCR en España y Portugal durante 3 años en pacientes pediátricos con trastornos neurológicos de origen desconocido. Pacientes y método: Se estudió a 127 individuos control y 283 pacientes con trastornos neurológicos de origen desconocido. El análisis de NT se realizó mediante HPLC con detección electroquímica y el análisis de pterinas y 5-MTHF, mediante HPLC con detección de fluorescencia. Resultados: Se ha diagnosticado 3 deficiencias de tirosina hidroxilasa en una misma familia, 2 casos de distonía sensible a L-dopa, 2 familias con defiencia de guanosinatrifosfato-ciclohidrolasa dominante (14 casos), 2 deficiencias del transportador de glucosa y 43 deficiencias de folato en LCR. Conclusiones: Este estudio ha permitido el diagnóstico de nuevos pacientes y, lo que es más importante, el establecimiento en todos ellos de un tratamiento farmacológico o nutricional. Las deficiencias de 5-MTHF han sido las más frecuentes y se las ha detectado en diferentes grupos de pacientes

Background and objective: In the last few years, it has been described inborn errors of neurotransmitter and pterin metabolism and defects in folate and glucose transport across blood brain barrier. All these defects are classified as rare diseases and needs cerebrospinal fluid (CSF) sample analysis for diagnosis. Our aim was to evaluate the results of the application of a CSF analysis protocol in a pediatric population from Spain and Portugal presenting with neurological disorders of unknown origin. Patients and method: We studied CSF samples from and 283 patients with neurological disorders of unknown origin and 127 controls. Neurotransmitters were analysed by HPLC with electrochemical detection, and pterins and 5-methyltetrahydrofolate were determined by HPLC with fluorescence detection. Results: We diagnosed 3 patients with tyrosine hidroxylase deficiency, 2 with dopa responsive dystonia, 14 with GTP-ciclohydrolase deficiency, 2 with glucose transport deficiency and 43 with cerebral folate deficiency. Conclusions: This study allowed us to diagnose new patients, and more importantly, the establishment in all of them of a pharmacological or nutritional treatment. The most frequent defect found was CSF 5-methyltetrahydrofolate deficiency, which was present in different groups of patients

The significance of elevated CSF lactate.

The final diagnosis of 158 patients who had a cerebrospinal fluid (CSF) lactate concentration greater than 2 mmol/l was ascertained. The conditions included seizures, inflammatory changes, and proven metabolic disorders. For the diagnosis of congenital lactic acidoses, CSF lactate should ideally be measured in a seizure free patient after any acute illness.

[Inborn errors of neurotransmitters in neuropaediatrics]. / Errores congénitos de los neurotransmisores en Neuropediatría.

AIMS: The aim of this work is to describe the clinical, biochemical and genetic characteristics of neurotransmitter diseases at the paediatric age, together with possible forms of treatment. We also sought to determine the diagnostic methodology of these disorders (collection and analysis of samples). DEVELOPMENT: These diseases essentially consist of a deficit of biogenic amines and alterations in GABA metabolism (gamma-aminobutyric acid). Disorders affecting the neurotransmission of biogenic amines often present in the form of hypokinesia, trunk hypotonia with increased limb tone, oculogyric crises, ptosis, faulty temperature regulation or abnormal movements. Defects in GABA metabolism give rise to epileptic encephalopathies and unspecific mental retardation, sometimes associated to signs of cerebellar dysfunction, convulsions and alterations in neuroimaging studies. Overall incidence of these diseases is low but they are unquestionably under-diagnosed, since they cannot be detected by conventional studies in plasma and urine, and require extraction and directed analysis of cerebrospinal fluid (CSF) for their detection. Additionally, the CSF study must be carried out in specific standardised conditions. Segawa's disease, or dopa-responsive dystonia, responds extremely well to therapy, whereas the other entities respond in varying ways to the different therapeutic alternatives. CONCLUSIONS: It is important for the paediatrician to know about these entities as a group of treatable neurometabolic diseases. Moreover, their detection would allow prenatal diagnosis in the vast majority of cases.

Cerebral folate deficiency.

Cerebral folate deficiency (CFD) can be defined as any neurological syndrome associated with low cerebrospinal fluid (CSF) 5-methyltetrahydrofolate (5MTHF), the active folate metabolite, in the presence of normal folate metabolism outside the nervous system. CFD could result from either disturbed folate transport or from increased folate turnover within the central nervous system (CNS). We report on a novel neurometabolic syndrome in 20 children, which we term 'idiopathic CFD'. Typical features became manifest from the age of 4 months, starting with marked unrest, irritability, and sleep disturbances followed by psychomotor retardation, cerebellar ataxia, spastic paraplegia, and dyskinesia; epilepsy developed in about one third of the children. Most children showed deceleration ofhead growth from the age of 4 to 6 months. Visual disturbances began to develop around the age of 3 years and progressive sensorineural hearing loss started from the age of 6 years. Neuroimaging showed atrophy of frontotemporal regions and periventricular demyelination in seven children, slowly progressive supra- and infratentorial atrophy in three children, and normal findings in the remainder. Because active folate transport to the CNS occurs through receptor-mediated folate receptor protein 1 (FR1) endocytosis, DNA sequencing of the FR1 gene was performed and found to be normal. However, CSF protein analysis revealed a non-functional FR1 protein, suspected to result from either post-translational defects of FR1 protein N-glycosylation, the presence of folate antagonists with irreversible binding, or autoantibodies blocking the folate binding site of FR1. Oral treatment with 5-formyltetrahydrofolate (folinic acid) should be started in low doses at 0.5-1mg/kg/day, but in some patients higher daily doses of folinic acid at 2-3 mg/kg/day are required to normalize CSF 5MTHF values. This proposed treatment protocol resulted in a favourable clinical response in patients identified before the age of six years while partial recovery with poorer outcome was found beyond the age of 6 years. Careful clinical and EEG monitoring should be performed 1, 3, and 6 months after the beginning of treatment. After four to six months of folinic acid treatment, CSF analysis should be repeated in order to prevent over- or under-dosage of folinic acid. Secondary forms of CFD have been recognized during chronic use of antifolate and anticonvulsant drugs and in various known conditions such as Rett syndrome, Aicardi-Goutières syndrome, 3-phosphoglycerate dehydrogenase deficiency, dihydropteridine reductase deficiency, aromatic amino acid decarboxylase deficiency, and Kearns-Sayre syndrome. The pathogenic link between these underlying specific disease entities and the observed secondary CFD has not been resolved.

Significant behavioral disturbances in succinic semialdehyde dehydrogenase (SSADH) deficiency (gamma-hydroxybutyric aciduria).

We report two adult patients with succinic semialdehyde dehydrogenase deficiency, manifesting as gamma-hydroxybutyric aciduria. For both, the clinical presentation included significant behavioral disturbances and psychosis (hallucinations, disabling anxiety, aggressive behavior, and sleep disorder), leading to multiple therapeutic attempts. Intervention with benzodiazepines appeared most efficacious, resulting in decreased aggression and agitation and improvement in anxiety. A review of 56 published and unpublished studies of SSADH-deficient patients revealed that 42% manifested behavioral disturbances, whereas 13% (predominantly adults) displayed psychotic symptomatology. To explore the potential biochemical basis of these behavioral abnormalities, we studied cerebrospinal fluid derived from 13 patients, which revealed significantly elevated GHB (65- to 230-fold), high free and total GABA (up to threefold), and low glutamine. Although within the control range, homovanillic and 5-hydroxyindoleacetic acids (end products of dopamine and serotonin metabolism, respectively) showed a significant linear correlation with increasing GHB concentration, suggesting enhanced dopamine and serotonin turnover. We conclude that elevated GABA combined with low glutamine suggest disruption of the glial-neuronal glutamine/GABA/glutamate shuttle necessary for replenishment of neuronal neurotransmitters, whereas altered dopamine and serotonin metabolism may be causally linked to the hyperkinetic movement disorders and behavioral disturbances seen in SSADH-deficient patients.

Value of lumbar puncture in the diagnosis of infantile epilepsy and folinic acid-responsive seizures.

Seizures are one of the most frequently occurring neurologic phenomena in childhood; an inborn error of metabolism should always be considered in the diagnostic workup of patients with seizures after more common causes have been excluded. Many of the known inborn metabolic errors associated with seizures can be detected by metabolite measurement in urine or blood. It is now recognized, however, that there are several conditions in which peripheral metabolite profiles remain normal. Abnormal metabolism is indicated only by the accumulation or absence of specific metabolites within the central nervous system. Some of these disorders can be detected by in vivo magnetic resonance spectroscopy. More often, an etiology can be ascertained only by analysis of specific metabolites in cerebrospinal fluid. This review describes the utility of cerebrospinal fluid metabolite analysis in the differential diagnosis of inborn errors of metabolism that lead to infantile epilepsy. These include disorders of central nervous system energy metabolism, creatine synthesis and transport, serine biosynthesis, and glucose transport, together with defects affecting the gamma-aminobutyric acid (GABA), catecholamine, and serotonin neurotransmitter systems. In addition, information is provided regarding detection of an early-onset seizure disorder that responds to folinic acid.