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Ethyl linoleate in meconium: a biomarker for prenatal ethanol exposure.

BACKGROUND: Fetal alcohol syndrome, fetal alcohol effects, alcohol-related neurodevelopmental disorder, and alcohol-related birth defects, all terms referring to the spectrum of consequences of in utero exposure to ethanol, are a major public health burden. There is currently no laboratory test to identify newborns exposed to ethanol in utero. Meconium was analyzed for ethyl linoleate, a metabolite of ethanol, as a biological marker for fetal ethanol exposure. METHODS: Samples of meconium were obtained from 248 infants and analyzed for fatty acid ethyl esters. Detailed maternal alcohol, tobacco, and drug use histories were obtained within 1 month of giving birth. RESULTS: The detection of ethyl linoleate in meconium was called a positive test. The mean number of drinks reported per week in the month before pregnancy, the first trimester, and overall were significantly higher in the positive group (unadjusted: 9.2 +/- 1.9 vs. 4.3 +/- 1.4, p = 0.004; 7.3 +/- 1.7 vs. 3.8 +/- 1.2, p = 0.03; and 6.1 +/- 1.3 vs. 3.0 +/- 1.0, p = 0.006). A positive test was not associated with marijuana, cocaine, or tobacco use. Sensitivity and specificity of the test were 72% and 51% to distinguish women who reported 1 or more drinks/week in the third trimester from women who denied use, and 68% and 48% to distinguish women who used > or =1 drink/week from women who used <1 drink/week in the month before pregnancy. CONCLUSIONS: The presence of ethyl linoleate in meconium is the first reported biological marker for maternal ethanol use during pregnancy. Because of the inherent inaccuracy associated with the use of self-reporting, the establishment of true values of sensitivity and specificity will require validation where the presence, quantity, and timing of exposure to alcohol is known. Further validation of this marker will permit identification and intervention of at-risk infants.

Adult↗

Assessing and Managing Adolescents with School Problems.

Although school performance is highly influenced by socioeconomic and cultural forces, neurodevelopmental and psychological factors are major determinants of educational success. Clinicians should approach school problems as a health issue, with the specific objectives of determining whether a primary disease process or neurodevelopmental disorder is interfering with learning; providing medical evidence to support further evaluation of the patient; and offering medical treatment for conditions responsive to medication. The author also recognizes the value of effective collaboration with school staff and mental health professionals and primary care clinicians in assisting the adolescent patient to address his or her school difficulties.

Journal Article↗

Candidate gene analysis in Rett syndrome and the identification of 21 SNPs in Xq.

Rett syndrome (RTT) is an X-linked dominant neurodevelopmental disorder that affects females. Exclusion mapping studies using a new family with maternal inheritance of RTT defined Xq28 as the candidate region for the RTT gene. Six candidate genes were selected for mutation analysis based on their established expression patterns and known functions in the CNS. These are: Glutamate receptor subunit 3 (GLUR3), GABA receptor subunit alpha 3 (GABRA3), GABA receptor subunit e1 (GABRE1), Vacuolar ATPase subunit 1 (VATPS1, XAP3), the human homologue of plexin 3-SEX (XAP6) and the Synaptobrevin-like protein (SYBL1). Major rearrangements involving these genes were excluded by Southern analysis. No disease-causing mutations were found, but several single-nucleotide polymorphisms (SNPs) were detected. These SNPs will be useful in future linkage analysis and whole-genome association studies for other diseases. The genomic characterization of GLUR3 and GABRA3 will allow mutational analysis of these genes as candidates for other X-linked neurological disorders mapping to Xq25-Xq26 and Xq28.

Base Sequence↗

[Rett syndrome--an odd handicap affecting girls. A current 25-year follow-up in Western Sweden].

Rett syndrome, a complicated neurodevelopmental disorder exclusively affecting girls in early childhood, is now known to be one of the major worldwide causes of severe mental retardation in females. Although internationally unknown until the mid-1980s, under another designation it had been observed in Sweden since the early 1960s. The article consists in a review of current clinical, neurobiological and genetic knowledge of the syndrome, and a systematic penetration of data collected from the follow-up of a west Swedish series of 54 female patients, 5-57 years of age. Mortality in the series was 17 percent, with a median age at death of 24 years. In most cases death was sudden and unexpected.

Adolescent↗

A review of the effects of prenatal or early postnatal ethanol exposure on brain ligand-gated ion channels.

BACKGROUND: Ligand-gated ion channels mediate fast excitatory and inhibitory synaptic transmission in the developing central nervous system. These channels have been shown to have roles in neuronal proliferation, differentiation, and programmed cell death. Numerous studies over the past 10 years indicate that prenatal and/or early postnatal ethanol exposure affects neurotransmitter-gated ion channels. METHODS: We conducted a review of the relevant literature, identified by a computer-assisted literature search. This review presents an overview of studies performed with experimental preparations from the brains of rodents exposed to ethanol in utero and/or during the neonatal period and summarizes some of the salient issues that have developed in the course of these investigations. Differences in ethanol exposure paradigms and blood alcohol concentrations obtained in these studies are highlighted, and directions for future research are suggested. RESULTS: Most studies have focused on the effects of prenatal or early postnatal ethanol exposure on NMDA receptors. These studies show that ethanol exposure affects ligand binding, subunit expression, and function of this receptor. Fewer studies have examined ethanol's effects on ligand-gated ion channels other than NMDA receptors. For instance, a study reported changes in ligand binding to hippocampal kainate receptors. Another study found alterations in modulation of GABA(A) receptors by benzodiazepines and neurosteroids. CONCLUSIONS: These studies suggest that the effects of ethanol on brain ion channels may have a role in the pathophysiology of Alcohol-Related Neurodevelopmental Disorders and Fetal Alcohol Syndrome.

Animals↗

Reducing complications from alcohol use during pregnancy through screening.

Prenatal providers are reluctant to discuss alcohol use in the clinical setting, even though heavy alcohol use is associated with fetal alcohol syndrome (FAS) and fetal alcohol effects (FAE), sometimes known as alcohol-related neurodevelopmental disorder. Fourteen percent to 20% of pregnant women report drinking some alcohol during pregnancy. Approximately 0.2% to 1% meet the criteria for heavy drinking. Reducing drinking during pregnancy has the potential to reduce the risk for FAS and FAE. Routine screening for alcohol use during pregnancy followed by referrals for those considered to be at risk is recommended. Women are often more receptive to intervention during pregnancy, as they focus on positive health behaviors. A number of brief screening tools designed for use on a routine basis are reviewed. Physicians who learn to comfortably discuss alcohol use during pregnancy can help substantially reduce the impact of these disorders.

Adult↗

Development of spontaneous stereotyped behavior in deer mice: effects of early and late exposure to a more complex environment.

Abnormal repetitive behaviors such as stereotypies are associated with neurodevelopmental disorders and are often observed under conditions of environmental restriction, particularly early in development. Few studies, however, have systematically assessed the effects of environmental enrichment and almost no information is available as to whether a sensitive period exists for such enrichment effects. We hypothesized that spontaneous stereotypies exhibited by deer mice housed under standard laboratory conditions were the result of environmental restriction and that a sensitive period exists for the development/prevention of stereotypies. Exposure to a more complex environment early in the post-weaning period resulted in substantially less stereotypy in the complex environment. Importantly, this outcome was maintained even after mice were housed in standard cages for an identical period of time. Later exposure to the more complex environment also resulted in significantly lower levels of stereotypy compared to controls. These effects were observed in the experimental housing condition as well as in a standard test context. The effects of early and late enrichment support the importance of environmental restriction in the genesis of stereotype and provide support for the efficacy of early and late enrichment in the prevention of stereotypies.

Age Factors↗

Case with autistic syndrome and chromosome 22q13.3 deletion detected by FISH.

Autism is a rare neurodevelopmental disorder with a strong genetic component. Co-occurrence of autism and chromosomal abnormalities is useful to localize candidate regions that may include gene(s) implicated in autism determinism. Several candidate chromosomal regions are known, but association of chromosome 22 abnormalities with autism is unusual. We report a child with autistic syndrome and a de novo 22q13.3 cryptic deletion detected by FISH. Previously described cases with 22q13.3 deletions shared characteristic developmental and speech delay, but autism was not specifically reported. This case emphasizes a new candidate region that may bear a gene involved in autism etiopathogenesis. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:839-844, 2000.

Adolescent↗

Postnatal maturation of human GABAA receptors measured with positron emission tomography.

During brain development in nonhuman primates, there are large changes in GABAA receptor binding and subunit expression. An understanding of human GABAA receptor ontogeny is highly relevant in elucidating the pathophysiology of neurodevelopmental disorders in which GABAergic mechanisms play a role as well as in understanding differences that occur during development in the pharmacology of drugs acting on this system. We have measured age-related changes in the brain distribution of the GABAA receptor complex in vivo using positron emission tomography (PET) in epileptic children under evaluation for surgical treatment. PET imaging was performed using the tracer [11C]flumazenil (FMZ), a ligand that binds to alpha subunits of the GABAA receptor. FMZ binding was quantified using a two-compartment model yielding values for the volume of distribution (VD) of the tracer in tissue. All brain regions studied showed the highest value for FMZ VD at the youngest age measured (2 years), and the values then decreased exponentially with age. Medial temporal lobe structures, primary visual cortex, and thalamus showed larger differences between values for age 2 years and adults (approximately 50% decrease) than did basal ganglia, cerebellum, and other cortical regions (25-40% decreases). Furthermore, subcortical regions reached adult values earlier (14-17.5 years) than did cortical regions (18-22 years). The ontogeny data of FMZ VD from children may contribute to understanding regional differences in synaptic plasticity as well as improve rational therapeutic use of drugs acting at the GABAA receptor in the pediatric population.

Adolescent↗

[Analysis of the most frequent mutations in girls with Rett syndrome].

BACKGROUND: Rett syndrome is an X-linked dominant neurodevelopmental disorder affecting 1 from 10,000 to 15,000 females worldwide. The responsible gene, encoding methyl-CpG binding protein 2 was recently identified. Methyl-CpG binding protein 2 is thought to act as a global transcriptional repressor. In the methyl-CpG binding protein 2 gene are known 5 prevalent mutations that cause Rett syndrome. Four of them are detectable by restriction analysis. In this study we present the results of the molecular study of four prevalent mutations in the gene for methyl-CpG binding protein 2 in Czech and Slovak patients with Rett syndrome. METHODS AND RESULTS: 22 females with Rett syndrome were investigated by methods of molecular biology. Restriction analysis and direct sequencing of PCR products revealed in methyl-CpG binding protein 2 gene 3 different mutations (T158M, R168X, R270X) in six unrelated patients with Rett syndrome. Mutation R306C, frequent in Great Britain and Sweden, was not detected in our group of patients with Rett syndrome. CONCLUSIONS: The diagnosis of Rett syndrome and genetic counselling in affected families should go out from the close cooperation of the pediatric, neurologic, and genetic departments with the specialized laboratories dealing with the molecular biological diagnosis.

Adolescent↗

Estimating the prevalence of fetal alcohol syndrome. A summary.

Since the late 1970s, many studies have reported on the prevalence of fetal alcohol syndrome (FAS), alcohol-related birth defects (ARBD), and alcohol-related neurodevelopmental disorders (ARND). The three main types of research methods used in these studies are passive surveillance, clinic-based studies, and active case ascertainment. This article describes each of these methods, including their strengths and weaknesses, and summarizes the estimated prevalence of FAS produced by each of these approaches. The maternal risk factors associated with FAS and other alcohol-related anomalies include advanced maternal age, low socioeconomic status, frequent binge drinking, family and friends with drinking problems, and poor social and psychological indicators. Overall, the available literature points to a prevalence rate of FAS of 0.5 to 2 cases per 1,000 births in the United States during the 1980s and 1990s.

Abnormalities, Drug-Induced↗

An autosomal genomic screen for autism.

Autism is a severe neurodevelopmental disorder defined by social and communication deficits and ritualistic-repetitive behaviors that are detectable in early childhood. The etiology of idiopathic autism is strongly genetic, and oligogenic transmission is likely. The first stage of a two-stage genomic screen for autism was carried out by the Collaborative Linkage Study of Autism on individuals affected with autism from 75 families ascertained through an affected sib-pair. The strongest multipoint results were for regions on chromosomes 13 and 7. The highest maximum multipoint heterogeneity LOD (MMLS/het) score is 3.0 at D13S800 (approximately 55 cM from the telomere) under the recessive model, with an estimated 35% of families linked to this locus. The next highest peak is an MMLS/het score of 2.3 at 19 cM, between D13S217 and D13S1229. Our third highest MMLS/het score of 2.2 is on chromosome 7 and is consistent with the International Molecular Genetic Study of Autism Consortium report of a possible susceptibility locus somewhere within 7q31-33. These regions and others will be followed up in the second stage of our study by typing additional markers in both the original and a second set of identically ascertained autism families, which are currently being collected. By comparing results across a number of studies, we expect to be able to narrow our search for autism susceptibility genes to a small number of genomic regions.

Adolescent↗

Schizophrenia: a genetic perspective (review).

Schizophrenia is a complex neurodevelopmental disorder characterized by mental dysfunction across multiple domains of the brain. It affects 1% of world's general population and the nature of neurobiological lesions in the schizophrenic brain are not known. Although the exact etiology of the disorder is not understood, twin, family and adoption studies have provided consistent evidence that genetic factors play a major role in the pathogenesis. A genome-wide genetic linkage screen identified loci on chromosomes 1, 2, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 18, 22 and the X with positive lod scores, thus excluding a single major locus for schizophrenia. Association studies have generated disappointing results in identifying the susceptible DNA sequence variants and the anticipation hypothesis on trinucleotide repeat expansion provided equivocal results or lack of enthusiasm. Although there are no biological markers at present, the recent finding that human endogenous retrovirus is activated in cerebrospinal fluid as well as in the postmortem schizophrenic brain may change our understanding of the etiopathogenesis of this disease. Meanwhile, treatment with newly developed anti-psychotic drugs combined with educational and cognitive rehabilitation procedure may help the patients to cope with the illness.

Chromosome Mapping↗

Alcohol use among women of childbearing age--United States, 1991-1999.

Prenatal exposure to alcohol is one of the leading preventable causes of birth defects, mental retardation, and neurodevelopmental disorders in the United States. One of the national health objectives for 2010 is to increase to 94% the percentage of pregnant women abstaining from alcohol use [corrected]. During 1991-1995, alcohol use by pregnant women increased substantially, and alcohol use by nonpregnant women of childbearing age increased slightly. To characterize trends in alcohol use among women of childbearing age, CDC analyzed representative survey data from the Behavioral Risk Factor Surveillance System (BRFSS) during 1991-1999. This report summarizes the results of the analysis, which indicate that the rate of any alcohol use (i.e., at least one drink) during pregnancy has declined since 1995. However, rates of binge drinking (i.e., > or = 5 drinks on any one occasion) and frequent drinking (i.e., > or = 7 drinks per week or > or = 5 drinks on any one occasion) during pregnancy have not declined among nonpregnant women of childbearing age. Health-care providers should routinely screen women of childbearing age for alcohol use and counsel them about the adverse effects of alcohol use during pregnancy.

Adult↗

[Mutation spectrum and genotype-phenotype correlation of MECP2 in patients with Rett syndrome].

Rett syndrome (RTT) is an X-linked dominant neurodevelopmental disorder characterized by regression in cognition and adaptability with autistic behavior, stereotypical hand movements, epilepsy and ataxia. Over 120 different mutations in the methyl-CpG binding protein 2 gene (MECP2) have been reported in patients with RTT, but a genotype-phenotype correlation has not been established. We have studied MECP2 mutations in 142 Japanese sporadic patients diagnosed clinically as having RTT. Forty different mutations in MECP2 have been detected in 103 female patients. Common mutations were four missense mutations (T158M,P152R, R133C and R306C) observed in 34 cases and four nonsense mutations (R168X, R255X, R270X and R294X) detected in 38 cases. Among these, R133C, R306C, and R294X were associated with atypical RTT including the preserved speech variant type, T158M and R168X with typical clinical features of RTT, and P152R, R255X, and R270X with severe developmental delay. These results suggest a genotype-phenotype correlation RTT. However, a large scale study of adult RTT patients is required to determine more precisely the influence of MECP2 mutation types on the natural history and clinical phenotypes of RTT.

Chromosomal Proteins, Non-Histone↗

Developmental profile of serum nerve growth factor levels in Rett complex.

Rett syndrome (RS) is a progressive neurodevelopmental disorder predominant in females, characterised by mental deficiency, stereotyped hand-washing and apraxia. Notwithstanding the recent identification of the MECP2 gene likely involved in the pathogenesis of SR, the neurobiological bases of this syndrome are still largely unknown. Converging evidence shows that the brain levels of nerve growth factor (NGF), a neurotrophin regulating the development and functioning of central cholinergic neurons, are decreased in RS girls. In this study, the serum levels of NGF were measured in classic RS, in the preserved speech variant (PSV) and in normal controls. Overall analysis failed to evidence significant differences among the three groups. However, whereas NGF levels increased significantly with age in controls, the opposite profile was observed in classic RS, with a progressive age-dependent decrease of NGF. In PSV subjects NGF levels remained constant with age. These findings strengthen the hypothesis of NGF involvement in the pathogenesis of RS.

Adolescent↗

[Genotype-phenotype correlations in Rett syndrome: the study of Russian cohort of patients].

Rett syndrome (RTT) is a severe neurodevelopmental disorder caused by mutations in methyl-CpG-binding protein 2 gene (MECP2). We carried out a mutations analysis in Russian cohort of patients with RTT. MECP2 mutations were found in 23 of 28 RTT girls and one boy (82%). Thirteen different types of mutations have been identified: 6 nonsense, 5 missense and 2 deletions in MECP2 gene. In typical RTT form, most frequent mutations were R255X (5 cases) and T158M (4 cases). A boy with classical clinical picture of RTT had R270X mutation. Skewed inactivation of chromosome x has been found in 2 of 27 RTT girls with classical RTT form and "forme fruste". The data obtained imply possible correlations between genotype and phenotype in RTT.

Child↗

Absence of Ndn, encoding the Prader-Willi syndrome-deleted gene necdin, results in congenital deficiency of central respiratory drive in neonatal mice.

necdin (Ndn) is one of a cluster of genes deleted in the neurodevelopmental disorder Prader-Willi syndrome. necdin is upregulated during neuronal differentiation and is thought to play a role in cell cycle arrest in terminally differentiated neurons. Most necdin-deficient Ndn(tm2Stw) mutant pups carrying a targeted replacement of Ndn with a lacZ reporter gene die in the neonatal period of apparent respiratory insufficiency. We now demonstrate that the defect can be explained by abnormal neuronal activity within the putative respiratory rhythm-generating center, the pre-Bötzinger complex. Specifically, the rhythm is unstable with prolonged periods of depression of respiratory rhythmogenesis. These observations suggest that the developing respiratory center is particularly sensitive to loss of necdin activity and may reflect abnormalities of respiratory rhythm-generating neurons or conditioning neuromodulatory drive. We propose that necdin deficiency may contribute to observed respiratory abnormalities in individuals with Prader-Willi syndrome through a similar suppression of central respiratory drive.

Animals↗