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People with intellectual disability are a vulnerable cohort who face challenges accessing health care. Compared with the general population, people with intellectual disability have an elevated risk of developing dementia, which often presents at a younger age and with atypical symptoms. The lifelong cognitive and functional difficulties faced by people with intellectual disability further complicate the diagnostic process. Specialised intellectual disability memory services and evaluation using reliable biomarkers of neurodegeneration are needed to improve diagnostic and prognostic certainty in this group. Inadequate specialist services and paucity of research on biomarkers in this population hinders progress and impedes the delivery of adequate health care. Although cerebrospinal fluid-based biomarkers and radiological biomarkers are used routinely in the evaluation of Alzheimer's disease in the general population, biological variation within the clinically heterogenous group of people with intellectual disability could affect the clinical utility of existing biomarkers. As disease-modifying therapies become available for the treatment of early Alzheimer's disease, and hopefully other neurodegenerative conditions in the future, biomarkers will serve as gatekeepers to establish the eligibility for such therapies. Inadequate representation of adults with intellectual disability in biomarker research will result in their exclusion from treatment with disease-modifying therapies, thus perpetuating the inequity in health care that is already faced by this group. The aim of this Series paper is to summarise current evidence on the application of biomarkers for Alzheimer's disease in a population with intellectual disability (that is not attributable to Down syndrome) and suspected cognitive decline., Competing Interests: Declaration of interests We declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Introduction: 6-Pyruvoyl-tetrahydropterin synthase deficiency (PTPSd) is a rare autosomal recessive disorder of synthesis of biogenic amines, which is characterized by variable neurological impairment and hyperphenylalaninemia. We aimed to assess the long-term clinical outcome of this disorder and the factors affecting it., Methods: At total of 28 PTPSd patients (aged 19.9 ± 10.9 years) underwent clinical (neurological and psychiatric) and neuropsychological assessment (BRIEF, VABS-II, and IQ). Based on CSF homovanillic (HVA) and 5-hydroxyindolacetic acid (5-HIAA) and pterin concentrations at diagnosis, patients were classified as having either a severe [SF; low level of CSF, HVA, and 5-HIAA with altered neopterin/biopterin (Neo/Bio)] or mild form (MF; normal HVA and 5-HIAA with altered Neo/Bio) of PTPSd., Results: Approximately 36% of patients had MF PTPSd. At the last examination, 43% of patients had movement disorders (2 MF, 10 SF), 43% of patients had variable degrees of intellectual disability (SF only), 39% met the criteria for a psychiatric disorder (3 MF, 9 SF). Applying a linear regression model, we found that HVA and phenylalanine levels at birth had a significant influence on IQ, BRIEF, and VABS-II variability. Lastly, 5-HIAA further contributed to VABS-II variability. The disease showed a self-limiting clinical course and its treatment, although delayed, is effective in improving the neurological status., Conclusions: Neurodevelopmental impairment due to PTPSd shows a self-limiting course. A continuous improvement in the neurological condition has been observed in patients receiving treatment, even when delayed. The severity of brain biogenic amine depletion at diagnosis predicts neurological and psychiatric outcomes., (Copyright © 2020 Elsevier Inc. All rights reserved.)

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., (© 2018 Mac Keith Press.)

Objective: To investigate growth factor changes in cerebrospinal fluid (CSF) of children with mental retardation (MR) before and after neural precursor cell transplantation (NPCT), in an attempt to provide experimental support for the clinical treatment of MR with NPCT., Methods: The study comprised of 28 MR children who received twice NPCT in our hospital. CSF was collected at both times of NPCT to assess growth factors by ELISA. In addition, the content of insulinlike growth factor 1 (IGF-1) in CSF was assayed to determine possible correlations between IGF-1 changes and the short-term therapeutic effect of NPCT., Results: Of all the growth factors detected in CSF, only IGF-1 was increased significantly after NPCT (P<0.05). Fifteen of the twenty-eight MR children achieved short-term therapeutic efficacy, whereby the content of IGF-1 after NPCT was significantly higher than that before NPCT (P<0.05). There was no difference in IGF-1 content before and after NPCT in the remaining 13 MR children without shortterm therapeutic effect (P=0.657). There was a significant difference in IGF-change between the two groups of patients (P<0.05)., Conclusion: IGF-1 may be one of the mechanisms contributing to the therapeutic effect of NPCT., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Disclaimer: These ACMG Standards and Guidelines are intended as an educational resource for clinical laboratory geneticists to help them provide quality clinical laboratory genetic services. Adherence to these standards and guidelines is voluntary and does not necessarily assure a successful medical outcome. These Standards and Guidelines should not be considered inclusive of all proper procedures and tests or exclusive of others that are reasonably directed to obtaining the same results. In determining the propriety of any specific procedure or test, clinical laboratory geneticists should apply their professional judgment to the specific circumstances presented by the patient or specimen. Clinical laboratory geneticists are encouraged to document in the patient's record the rationale for the use of a particular procedure or test, whether or not it is in conformance with these Standards and Guidelines. They also are advised to take notice of the date any particular guideline was adopted, and to consider other relevant medical and scientific information that becomes available after that date. It also would be prudent to consider whether intellectual property interests may restrict the performance of certain tests and other procedures.Cerebral creatine deficiency syndromes are neurometabolic conditions characterized by intellectual disability, seizures, speech delay, and behavioral abnormalities. Several laboratory methods are available for preliminary and confirmatory diagnosis of these conditions, including measurement of creatine and related metabolites in biofluids using liquid chromatography-tandem mass spectrometry or gas chromatography-mass spectrometry, enzyme activity assays in cultured cells, and DNA sequence analysis. These guidelines are intended to standardize these procedures to help optimize the diagnosis of creatine deficiency syndromes. While biochemical methods are emphasized, considerations for confirmatory molecular testing are also discussed, along with variables that influence test results and interpretation.Genet Med 19 2, 256-263.

Nonketotic hyperglycinemia is a rare metabolic disorder with severe, frequently fatal, neurologic manifestations. Reliable and accurate diagnosis depends on careful interpretation of laboratory findings. The clinical suspicion should lead to determination of glycine in plasma and cerebrospinal fluid. Amino acid analysis presents diagnostic values for classic nonketotic hyperglycinemia, but it also should be performed in suspected cases of atypical nonketotic hyperglycinemia and in children with seizures, failure to thrive, behavior problems, and uncoordinated movements. Clinical assessment should be reinforced by demonstration of elevated cerebrospinal fluid-to-plasma glycine ratio. Confirmatory diagnosis requires enzymatic and genetic investigation of glycine cleavage system. An early diagnosis, though not affecting clinical outcome, allows proper genetic counseling, with the possibility of prenatal diagnosis. We report 3 cases of nonketotic hyperglycinemia, 2 typical neonatal and 1 atypical, diagnosed in Pediatric Hospital of Coimbra, Portugal, and investigated at Laboratory of Biochemical Genetics in 2004 to 2010 (incidence 1:47 455; prevalence 1:782 951).

Recessive mutations in the mitochondrial arginyl-transfer RNA synthetase (RARS2) gene have been associated with early onset encephalopathy with signs of oxidative phosphorylation defects classified as pontocerebellar hypoplasia 6. We describe clinical, neuroimaging and molecular features on five patients from three unrelated families who displayed mutations in RARS2. All patients rapidly developed a neonatal or early-infantile epileptic encephalopathy with intractable seizures. The long-term follow-up revealed a virtual absence of psychomotor development, progressive microcephaly, and feeding difficulties. Mitochondrial respiratory chain enzymes in muscle and fibroblasts were normal in two. Blood and CSF lactate was abnormally elevated in all five patients at early stages while appearing only occasionally abnormal with the progression of the disease. Cerebellar vermis hypoplasia with normal aspect of the cerebral and cerebellar hemispheres appeared within the first months of life at brain MRI. In three patients follow-up neuroimaging revealed a progressive pontocerebellar and cerebral cortical atrophy. Molecular investigations of RARS2 disclosed the c.25A>G/p.I9V and the c.1586+3A>T in family A, the c.734G>A/p.R245Q and the c.1406G>A/p.R469H in family B, and the c.721T>A/p.W241R and c.35A>G/p.Q12R in family C. Functional complementation studies in Saccharomyces cerevisiae showed that mutation MSR1-R531H (equivalent to human p.R469H) abolished respiration whereas the MSR1-R306Q strain (corresponding to p.R245Q) displayed a reduced growth on non-fermentable YPG medium. Although mutations functionally disrupted yeast we found a relatively well preserved arginine aminoacylation of mitochondrial tRNA. Clinical and neuroimaging findings are important clues to raise suspicion and to reach diagnostic accuracy for RARS2 mutations considering that biochemical abnormalities may be absent in muscle biopsy.

Many reports in the field of childhood brain disorders have documented that brain-derived neurotrophic factor (BDNF) affects central nervous system (CNS) functions. In this clinical study, BDNF levels were evaluated in association with pediatric CNS infections. BDNF levels in the serum and cerebrospinal fluid (CSF) of 42 patients admitted during 5-year period, due to CNS infections, were measured by enzyme-linked immunosorbent assays (ELISAs). Control samples were collected from 108 patients with non-CNS infections (urinary tract infection, acute upper respiratory infection, acute gastroenteritis, etc.). Mean values of BDNF levels, at various ages, were determined and compared. BDNF levels were below the sensitivity of the ELISA in most CSF samples from the control group, but were significantly elevated in the patients with bacterial meningitis. The serum BDNF levels were elevated in all subgroups of patients with CNS infections, and the elevation was particularly notable in those with bacterial meningitis. BDNF expression in the CSF was correlated with CSF interleukin (IL)-6 levels as well as with blood platelet counts and neurological prognoses in those with bacterial meningitis. No correlation was found between BDNF levels and serum leukocyte numbers or C-reactive protein (CRP) levels. BDNF levels were found to be elevated in the serum and CSF of pediatric patients with CNS infections, particularly those with bacterial meningitis. Monitoring the changes in serum and CSF levels of BDNF may facilitate the diagnosis of acute meningitis and acute encephalopathy and allow the differential diagnosis of specific CNS infections.

Background: Acute encephalopathy includes rapid deterioration and has a poor prognosis. Early intervention is essential to prevent progression of the disease and subsequent neurologic complications. However, in the acute period, true encephalopathy cannot easily be differentiated from febrile seizures, especially febrile seizures of the complex type. Thus, an early diagnostic marker has been sought in order to enable early intervention. The purpose of this study was to identify a novel marker candidate protein differentially expressed in the cerebrospinal fluid (CSF) of children with encephalopathy using proteomic analysis., Methods: For detection of biomarkers, CSF samples were obtained from 13 children with acute encephalopathy and 42 children with febrile seizure. Mass spectral data were generated by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) technology, which is currently applied in many fields of biological and medical sciences. Diagnosis was made by at least two pediatric neurologists based on the clinical findings and routine examinations. All specimens were collected for diagnostic tests and the remaining portion of the specimens were used for the SELDI-TOF MS investigations., Results: In experiment 1, CSF from patients with febrile seizures (n = 28), patients with encephalopathy (n = 8) (including influenza encephalopathy (n = 3), encephalopathy due to rotavirus (n = 1), human herpes virus 6 (n = 1)) were used for the SELDI analysis. In experiment 2, SELDI analysis was performed on CSF from a second set of febrile seizure patients (n = 14) and encephalopathy patients (n = 5). We found that the peak with an m/z of 4810 contributed the most to the separation of the two groups. After purification and identification of the 4.8-kDa protein, a 4.8-kDa proteolytic peptide fragment from the neurosecretory protein VGF precursor (VGF4.8) was identified as a novel biomarker for encephalopathy., Conclusions: Expression of VGF4.8 has been reported to be decreased in pathologically degenerative changes such as Alzheimer's disease, amyotrophic lateral sclerosis (ALS), frontotemporal dementia, and encephalopathy. Thus, the VGF4.8 peptide might be a novel marker for degenerative brain conditions.

This study assessed the effects of haptic information on the postural control systems of individuals with intellectual disabilities (ID), through the use of a nonrigid tool that we call the "anchor system" (e.g., ropes attached to graduated weights that rest on the floor). Eleven participants with ID were asked to stand, blindfolded, on a balance beam placed at two heights (10 and 20 cm), for 30 s, while using the anchor system at two weights. The lighter anchor weight appeared to improve the individuals' balance in contrast to a control task condition; therefore, we concluded that haptic sensitivity was more significant in helping to orient the body than was the anchor's mechanical support alone.

Neurofilament (NF) is one of the major cytoskeleton proteins of neurons. We investigated the concentrations of the heavy subunit of NF (NF-H) in cerebrospinal fluid (CSF) as biomarkers of neuronal injury in bacterial meningitis. Concentrations of NF-H in CSF of 26 children with bacterial meningitis and in 16 control subjects were measured by ELISA. The CSF NF-H levels were elevated in 22 of the 26 children (85%) with bacterial meningitis. The peak CSF NF-H level occurred at a median period of 10.5 days after onset of illness (range, 1 to 35 days). The peak CSF NF-H levels of the patients with neurological sequelae (n=4) were significantly higher than those without sequelae (n=22) (7.06 vs. 2.46 ng/mL as median, p=0.048). There was no significant difference in CSF NF-H levels between patients with and without severe neurological sequelae up to day 14 of illness, but the CSF NF-H levels in patients with sequelae were significantly higher than in those without sequelae after day 14 of illness (2.04 vs. 1.19 ng/mL as median, p=0.024). We suggest that neuronal injury occurs in bacterial meningitis regardless of the presence or absence of neurological sequelae.

A 12-year-old African American boy with mental retardation and Asperger's disorder presented with acute psychosis. Antiphospholipid antibody testing with enzyme-linked immunosorbent assay showed increased levels of immunoglobulin G anticardiolipin antibodies in the cerebrospinal fluid, but not in the serum. Although antiphospholipid antibodies have been reported in the serum of patients with thrombotic and neurologic disorders, there are only a few reports of these antibodies in cerebrospinal fluid. This finding is consistent with a recent report of antiphospholipid antibodies found in the cerebrospinal fluid of adults with acute psychosis.

Introduction: Normal brain development and function depend on the active transport of folates across the blood-brain barrier. The folate receptor-1 (FR 1) protein is localized at the basolateral surface of the choroid plexus, which is characterized by a high binding affinity for circulating 5-methyltetrahydrofolate (5-MTHF)., Patients and Methods: We report on the clinical and metabolic findings among five children with normal neurodevelopmental progress during the first four to six months followed by the acquisition of a neurological condition which includes marked irritability, decelerating head growth, psychomotor retardation, cerebellar ataxia, dyskinesias (choreoathetosis, ballism), pyramidal signs in the lower limbs and occasional seizures. After the age of six years the two oldest patients also manifested a central visual disorder. Known disorders have been ruled out by extensive investigations. Cerebrospinal fluid (CSF) analysis included determination of biogenic monoamines, pterins and 5-MTHF., Results: Despite normal folate levels in serum and red blood cells with normal homocysteine, analysis of CSF revealed a decline towards very low values for 5-methyltetrahydrofolate (5-MTHF), which suggested disturbed transport of folates across the blood-brain barrier. Genetic analysis of the FR 1 gene revealed normal coding sequences. Oral treatment with doses of the stable compound folinic acid (0.5-1 mg/kg/day Leucovorin(R)) resulted in clinical amelioration and normalization of 5-MTHF values in CSF., Conclusion: Our findings identified a new condition manifesting after the age of 6 months which was accompanied by low 5-MTHF in cerebrospinal fluid and responded to oral supplements with folinic acid. However, the cause of disturbed folate transfer across the blood-brain barrier remains unknown.

Creatine kinase isoenzyme BB was determined in cerebrospinal fluid (CSF) in 79 preterm neonates using an original enzyme-linked immunosorbent assay. The criterion for inclusion was an Apgar score of 7 or less at 5 min of life. Neurological examination was performed on day 2 and day 5 of life. CSF was obtained on the same days. Lumbar puncture was performed on 41 of these babies on day 2 and in 39 on day 5 of life (one baby underwent lumbar puncture twice). All babies had clinical features of hypoxic-ischemic encephalopathy (HIF) which was classified according to Sarnat and Sarnat. The control group consisted of 90 asphyxiated term babies and 30 adults without CNS pathology. The concentration of CK-BB in cerebrospinal fluid (mean +/- SD) was significantly higher (p < 0.0005) in preterm (168.0 +/- 2) than in term babies (29.0 +/- 3.1) and healthy adults (5.3 +/- 1.2). Our results demonstrate the possibility of using the classification system of Sarnat and Sarnat for assessment of the severity of brain damage not only in term, but also in preterm babies. Neonates with HIE stages II and III showed markedly higher CK-BB values than those with HIE I on day 2 (p < 0.025) and day 5 (p < 0.05) of life. CK-BB values were markedly higher in preterm babies with none of some primitive responses (head turning, Babkin's reflex, palmar grasp). The mean concentration of CK-BB was higher in neonates with retarded psychomotor development compared with those with normal development (p < 0.05) on day 3, and after 6 and 9 months. At 12 months of age no significant difference in median CK-BB concentration was detected between neonates with normal and developmental disturbances.

Concentrations of the four major brain gangliosides, GM1, GD1a, GD1b and GT1b, biochemical markers of neuronal membranes, were determined in the cerebrospinal fluid (CSF) of 20 children with autism and in 25 controls. In addition, the gangliosides were determined in children with different forms of non-progressive neurological disorders lacking clinical features of autism. GM1, GD1a, GD1b and GT1b were significantly increased in patients with autism compared with age-matched controls and children with non-progressive neurological disorders. The gangliosides have previously been shown to have a function in synaptic transmission and increased synaptic activity leads to added release of gangliosides. Our finding of increased CSF levels of gangliosides in autism suggests increased synaptic activity in this disorder.

After establishing more extended reference values for amino acids, purines and pyrimidines in cerebrospinal fluid (CSF) in infancy and childhood, we studied 1250 CSF-aliquots from patients who were undergoing a diagnostic lumbar puncture for diverse clinical indications. Our primary aim was to answer the question whether determination of the concentration of amino acids, purines and pyrimidines in CSF is a useful tool in screening for metabolic disorders in children with unexplained mental retardation. In unexplained mental retardation (95 patients) we observed varying abnormalities of CSF. These were reproducible in only 2 patients (a decrease of homocarnosine in combination with two unidentified compounds). Striking abnormalities in pyrimidine content which are limited to CSF are found in argininosuccinic aciduria and uraemia. In uraemia a general decrease in amino acids in CSF and increase of gamma-aminobutyric acid (GABA) was observed. The results obtained indicate that determination of amino acids, purines and pyrimidines in CSF is only of limited value in the diagnosis of unexplained mental retardation.

Metabolites of neurotransmitters, homovanillic acid (HVA) and 5-hydroxyindolacetic acid (5-HIAA) were assessed in the cerebrospinal fluid of 149 children of different age from neonatal age to 13 years by the method of high pressure liquid chromatography with electrochemical detection. The mean concentration of the two metabolites in cerebrospinal fluid correlated indirectly with the childrens age--the highest mean concentrations of HVA and 5-HIAA were found in the group of neonates, lower values in infants and the lowest ones in the group of toddlers and older children. In the group of toddlers and older children with severe mental disorders and repeated tonic-clonic or myoclonic seizures a lower mean 5-HIAA was found in the cerebrospinal fluid than in children of equal age, similarly mentally affected but without seizures in the case-history.

Cerebrospinal fluid (CSF) from twenty three patients with non specific mental retardation and fourteen age matched normal samples was subjected for qualitative analysis of protein profiles by two-dimensional gel electrophoresis (2-DE) and the proteins were visualised by ultra sensitive silver staining. Two proteins designated as mental retardation associated proteins (MRAP-I and MRAP-II) were identified in six male patients out of twenty three patients CSF samples. MRAP-I had an isoelectric point of 7.4 with a relative molecular weight 16.5 kDa, while MRAP-II had an iso-electric point of 7.2 with a relative molecular weight 16.8 kDa. The two proteins are presumed to be originated from brain, as they could not be traced in the serum of patients, nor due to proteolytic degradation. Despite unknown origin and identity, their presence in the CSF of a specific group of mentally retarded male patients suggest their possible clinical utility and to define protein alterations in mental retardation.

Norrie disease is an X-linked recessive disorder characterized by congenital blindness and, in many cases, mental retardation. Some Norrie disease cases have been shown to be associated with a submicroscopic deletion in chromosomal region Xp11.3. Cerebrospinal fluid (CSF) was collected from four male patients with an X-chromosomal deletion associated with Norrie disease. CSF proteins were resolved using two-dimensional gel electrophoresis and then analyzed by computer using the Elsie V program. Our analysis revealed a protein that appears to be altered in patients with Norrie disease deletion.

In 8 cases of typical neuroleptic malignant syndrome (NMS), homovanillic acid (HVA), 5-hydroxyindole acetic acid (5-HIAA), noradrenaline (NA), and 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) levels in the cerebrospinal fluid (CSF) were assayed during both the active phase of NMS and after recovery. Compared with levels in normal control subjects the levels of HVA were significantly lower in patients with active NMS. This finding supports the central dopamine blockade theory of NMS pathophysiology. In addition, the levels of HVA were significantly decreased after recovery, suggesting that there may be a decreased dopamine metabolism in patients susceptible to NMS. The levels of 5-HIAA in patients with active NMS and after recovery were also significantly lower than those in normal control group, suggesting a relationship between the development of NMS and a disturbance of serotonin metabolism. The levels of NA in patients with active NMS were significantly higher than in normal subjects, and were within normal range after recovery. The levels of MHPG had a tendency to increase in patients with active NMS, compared with levels during recovery. These findings are a result of increased sympathetic nervous system activity in patients with active NMS; however, they are also observed in other disorders and may well reflect the physical stress caused by NMS.

Complement-requiring neutralizing antibodies to herpes simplex type 1 virus (HSV 1) in titres from 2 to greater than 16 were detected in the cerebrospinal fluid (CSF) of 47% senile patients with various forms of dementia, but in none of mentally retarded adolescents and adults suffering from various neurologidal diseases. Also the incidence of HSV 1 serum antibodies in elevated titres (larger than or equal to 512) was increased in senile demented patients (61%) as compared with persons in normal senium (31%), normal adults (15%), mentally retarded adolescents (17%) and prisoned felons with low IQ (45-47%).

The behaviour of the CSF cells during gas encephalography (GEG) with O(2), N(2)O, and halothane is poorly known in cerebral developmental disorders. One hundred and fifty CSF samples taken during pneumoencephalography from 75 mentally retarded patients were examined cytologically by the millipore technique with Papanicolaou staining. The results were processed automatically. An approximately 25-fold increase in CSF cells (P<0·001), mainly meningeal, reticulohistiocytic, and monocytic types, was found to occur. The cortical gas filling rate had a positive correlation (P<0·001) with the increase of number of CSF cells. There were no significant differences between the cellular changes in different cerebral disorders. Thus, though the irritant effect of GEG gives a rich cell yield, diagnostic atypical cells in developmental disorders of the central nervous system probably rarely exfoliate into the lumbar CSF.

Determination of monoamine metabolites was accomplished in the spinal fluid of 22 psychotic children and in 22 sex- and almost-age-matched "normal" controls. Also, specimens from groups of mentally retarded children and children with progressive encephalopathy or meningitis were used for comparison. The psychotic children showed raised levels of homovanillic acid. Thirteen children diagnosed as autistic by Rutter's criteria showed isolated increase of this metabolite. In the group of 9 children with other psychoses, both the level of homovanillic acid and that of 5-hydroxy-indoleacetic acid was raised. The comparison with the group of "simply" mentally retarded children and results within the psychotic group revealed that the increased concentration of monoamines was not attributable to mental retardation per se.

Eighteen female patients are described with the clinical features of Rett syndrome. Fifteen patients fulfill the criteria established by Hagberg et al hereas three represent clinical variants. Detailed biochemical and neurodiagnostic assessment was conducted in all patients. Reduction in cerebrospinal biogenic amine metabolites and characteristic alterations in respiratory, sleep, and EEG patterns were helpful in supporting the clinical diagnosis in the fifteen patients with typical features of Rett syndrome. In the remaining three patients, the modalities were much less helpful in establishing the diagnosis. Until a molecular marker is defined, diagnosis must depend on careful clinical assessment.

Twenty 2- to 13-year-old infantile autistic children (16 boys and four girls) and four 4- to 13-year-old children (two boys and two girls) with other kinds of childhood psychoses were compared with eight 6-month-old to 6-year-old normal children with regard to cerebrospinal fluid contents of endorphin fractions I and II. The psychosis groups showed higher mean cerebrospinal fluid endorphin fraction II levels, and 11 (55%) of the 20 autistic patients showed values higher than the highest in the group of normal children. There was a trend toward a correlation between high fraction II levels and self-destructiveness and decreased pain sensibility in the psychotic children. The results are regarded as preliminary but as warranting further research in this potentially fruitful field.

In three infants with nonketotic hyperglycinemia, glycine was increased three-to fourfold in plasma, 13- to 28-fold in lumbar spinal fluid, and was higher yet in ventricular fluid. Oral sodium benzoate lowered cerebrospinal fluid (CSF) glycine by greater than 40%, but did not change the abnormal plasma: CSF ratio. An adult control, made hyperglycinemic with oral glycine, had a normal plasma: CSF ratio. Treatment of one patient with sodium benzoate from birth did not prevent mental retardation; the degree of brain stem depression was a function of CSF glycine in another patient. The persistance of glycine elevation in CSF, although therapy maintained normal concentration in plasma, appears to be caused by overproduction in brain and limitation of the high-capacity lumbar spinal reabsorptive mechanism. Treatment through lowering of CNS glycine by use of a ventricular shunt was explored.