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Protein kinase C enzymes play an important role in signal transduction, regulation of gene expression and control of cell division and differentiation. The fsI and βII isoenzymes result from the alternative splicing of the PKCβ gene (PRKCB1), previously found to be associated with autism. We performed a family-based association study in 229 simplex and 5 multiplex families, and a postmortem study of PRKCB1 gene expression in temporocortical gray matter (BA41/42) of 11 autistic patients and controls. PRKCB1 gene haplotypes are significantly associated with autism (P<0.05) and have the autistic endophenotype of enhanced oligopeptiduria (P<0.05). Temporocortical PRKCB1 gene expression was reduced on average by 35 and 31% for the PRKCB1-1 and PRKCB1-2 isoforms (P<0.01 and <0.05, respectively) according to qPCR. Protein amounts measured for the PKCβII isoform were similarly decreased by 35% (P=0.05). Decreased gene expression characterized patients carrying the ‘normal’ PRKCB1 alleles, whereas patients homozygous for the autism-associated alleles displayed mRNA levels comparable to those of controls. Whole genome expression analysis unveiled a partial disruption in the coordinated expression of PKCβ-driven genes, including several cytokines. These results confirm the association between autism and PRKCB1 gene variants, point toward PKCβ roles in altered epithelial permeability, demonstrate a significant downregulation of brain PRKCB1 gene expression in autism and suggest that it could represent a compensatory adjustment aimed at limiting an ongoing dysreactive immune process. Altogether, these data underscore potential PKCβ roles in autism pathogenesis and spur interest in the identification and functional characterization of PRKCB1 gene variants conferring autism vulnerability.Molecular Psychiatry (2009) 14, 705–718; doi:10.1038/mp.2008.21; published online 4 March 2008 [ABSTRACT FROM AUTHOR]

Autism spectrum disorders represent a group of developmental disorders with strong genetic underpinnings. Several cytogenetic abnormalities or de novo mutations able to cause autism have recently been uncovered. In this study, the literature was reviewed to highlight genotype-phenotype correlations between causal gene mutations or cytogenetic abnormalities and behavioural or morphological phenotypes. Based on this information, a set of practical guidelines is proposed to help clinical geneticists pursue targeted genetic testing for patients with autism whose clinical phenotype is suggestive of a specific genetic or genomic aetiology. [ABSTRACT FROM AUTHOR]

There is strong evidence for a genetic predisposition to autism and an intense interest in discovering heritable risk factors that disrupt gene function. Based on neurobiological findings and location within a chromosome 7q31 autism candidate gene region, we analyzed the gene encoding the pleiotropic MET receptor tyrosine kinase in a family based study of autism including 1,231 cases. MET signaling participates in neocortical and cerebellar growth and maturation, immune function, and gastrointestinal repair, consistent with reported medical complications in some children with autism. Here, we show genetic association (P = 0.0005) of a common C allele in the promoter region of the MET gene in 204 autism families. The allelic association at this MET variant was confirmed in a replication sample of 539 autism families (P = 0.001) and in the combined sample (P = 0.000005). Multiplex families, in which more than one child has autism, exhibited the strongest allelic association (P = 0.000007). In case-control analyses, the autism diagnosis relative risk was 2.27 (95% confidence interval: 1.41–3.65; P = 0.0006) for the CC genotype and 1.67 (95% confidence interval: 1.11–2.49; P = 0.012) for the CG genotype compared with the GG genotype. Functional assays showed that the C allele results in a 2-fold decrease in MET promoter activity and altered binding of specific transcription factor complexes. These data implicate reduced MET gene expression in autism susceptibility, providing evidence of a previously undescribed pathophysiological basis for this behaviorally and medically complex disorder. [ABSTRACT FROM AUTHOR]

The human gene encoding Reelin ( RELN), a pivotal protein in neurodevelopment, includes a polymorphic GGC repeat in its 5′ untranslated region (UTR). CHO cells transfected with constructs encompassing the RELN 5′UTR with 4-to-13 GGC repeats upstream of the luciferase reporter gene show declining luciferase activity with increasing GGC repeat number (P < 0.005), as predicted by computer-based simulations. Conversely, RELN 5′UTR sequences boost reporter gene expression above control levels in neuronal SN56 and N2A cell lines, but 12- and 13-repeat alleles still yield 50–60% less luciferase activity compared to the more common 8- and 10-repeat alleles (P < 0.0001). RELN “long” GGC alleles significantly blunt gene expression and may, through this effect, confer vulnerability to human disorders, such as schizophrenia and autism. [ABSTRACT FROM AUTHOR]

Objective: Autism is a complex, largely genetic psychiatric disorder. In the majority of cases, the cause of autism is not known, but there is strong evidence for a genetic etiology. To identify candidate genes, the physical mapping of balanced chromosomal aberrations is a powerful strategy, since several genes have been characterized in numerous disorders. In this study, the authors analyzed a balanced reciprocal translocation arising de novo in a subject with autism and mental retardation. Method: The authors performed the physical mapping of the balanced 9q23/10q22 translocation by fluorescent in situ hybridization experiments using bacterial artificial chromosome clones covering the areas of interest. Results: Findings revealed that the KCNMA1 gene, which encodes the alpha-subunit of the large conductance Ca2+-activated K+ (BKCa) channel, a synaptic regulator of neuronal excitability, is physically disrupted. Further molecular and functional analyses showed the haploinsufficiency of this gene as well as decreased activity of the coded BKCa channel. This activity can be enhanced in vitro by addition of a BKCa channel opener (BMS-204352). Further mutational analyses on 116 autistic subjects led to the identification of an amino acid substitution located in a highly conserved domain of the protein not found in comparison subjects. Conclusions: These results suggest a possible association between a functional defect of the BKCa channel and autistic disorder and raise the hypothesis that deficits in synaptic transmission may contribute to the physiopathology of autism and mental deficiency. [ABSTRACT FROM AUTHOR]

Our understanding of human disorders that affect higher cognitive functions has greatly advanced in recent decades, and over 20 genes associated with non-syndromic mental retardation have been identified during the past 15 years. However, proteins encoded by ‘cognition genes’ have such diverse neurodevelopmental functions that delineating specific pathogenetic pathways still poses a tremendous challenge. In this review, we summarize genetic, epigenetic and environmental contributions to neurodevelopmental alterations that either cause or confer vulnerability to autism, a disease primarily affecting social cognition. Taken together, these results begin to provide a unifying view of complex pathogenetic pathways that are likely to lead to autism spectrum disorders through altered neurite morphology, synaptogenesis and cell migration. This review is part of the INMED/TINS special issue Nature and nurture in brain development and neurological disorders, based on presentations at the annual INMED/TINS symposium (http://inmednet.com/). [Copyright &y& Elsevier]

Organophosphates (OPs) are routinely used as pesticides in agriculture and as insecticides within the household. Our prior work on Reelin and APOE delineated a gene–environment interactive model of autism pathogenesis, whereby genetically vulnerable individuals prenatally exposed to OPs during critical periods in neurodevelopment could undergo altered neuronal migration, resulting in an autistic syndrome. Since household use of OPs is far greater in the USA than in Italy, this model was predicted to hold validity in North America, but not in Europe. Here, we indirectly test this hypothesis by assessing linkage/association between autism and variants of the paraoxonase gene (PON1) encoding paraoxonase, the enzyme responsible for OP detoxification. Three functional single nucleotide polymorphisms, PON1 C−108T, L55M, and Q192R, were assessed in 177 Italian and 107 Caucasian-American complete trios with primary autistic probands. As predicted, Caucasian-American and not Italian families display a significant association between autism and PON1 variants less active in vitro on the OP diazinon (R192), according to case–control contrasts (Q192R: χ2=6.33, 1 df, P<0.025), transmission/disequilibrium tests (Q192R: TDT χ2=5.26, 1 df, P<0.025), family-based association tests (Q192R and L55M: FBAT Z=2.291 and 2.435 respectively, P<0.025), and haplotype-based association tests (L55/R192: HBAT Z=2.430, P<0.025). These results are consistent with our model and provide further support for the hypothesis that concurrent genetic vulnerability and environmental OP exposure may possibly contribute to autism pathogenesis in a sizable subgroup of North American individuals.Molecular Psychiatry (2005) 10, 1006–1016. doi:10.1038/sj.mp.4001714; published online 19 July 2005 [ABSTRACT FROM AUTHOR]

Summary. The serotonin transporter (5HTT) is the molecule responsible for the high-affinity reuptake of 5HT from the synaptic cleft. Mice lacking the 5HTT exhibit highly elevated extracellular concentrations of 5HT. We assessed whether the glutathione detoxification system is altered in 5HTT-deficient mice. While levels of reduced and oxidized glutathione were unchanged, glutathione metabolising enzymes showed a differential pattern of modulation. Glutathione peroxidase was reduced in frontal cortex, brainstem, and cerebellum of 5HTT-deficient mice, though not to a statistically significant extent, while a putative isoform of the detoxifying enzyme glutathione-S-transferase pi was decreased in a number of brain regions, especially in brainstem. At the level of the DNA, we found an increase of oxidative DNA adducts in the hippocampus of 5HTT-deficient mice. Given the importance of the hippocampus in learning and memory, this may be the most important neurochemical consequence of the absence of the 5HTT. [ABSTRACT FROM AUTHOR]

Autism Spectrum Disorder (ASD) is a severe and lifelong neurodevelopmental disorder, with high social costs and a dramatic burden on the quality of life of patients and family members. Despite its high prevalence, reaching 1/54 children and 1/45 adults in the United States, no pharmacological treatment is still directed to core symptoms of ASD, encompassing social and communication deficits, repetitive behaviors, restricted interests, and abnormal sensory processing. The purpose of this review is to provide an overview of the state-of-the-art of psychopharmacological therapy available today for ASD in children and adolescents, in order to foster best practices and to organize new strategies for future research. To date, atypical antipsychotics such as risperidone and aripiprazole represent the first line of intervention for hyperactivity, impulsivity, agitation, temper outbursts or aggression towards self or others. Tricyclic antidepressants are less prescribed because of uncertain efficacy and important side effects. SSRIs, especially fluoxetine and sertraline, may be effective in treating repetitive behaviors (anxiety and obsessive-compulsive symptoms) and irritability/agitation, while mirtazapine is more helpful with sleep problems. Low doses of buspirone have shown some efficacy on restrictive and repetitive behaviors in combination with behavioral interventions. Stimulants, and to a lesser extent atomoxetine, are effective in reducing hyperactivity, inattention and impulsivity also in comorbid ASD-ADHD, although with somewhat lower efficacy and greater incidence of side effects compared to idiopathic ADHD. Clonidine and guanfacine display some efficacy on hyperactivity and stereotypic behaviors. For several other drugs, case reports and open-label studies suggest possible efficacy, but no randomized controlled trial has yet been performed. Research in the pediatric psychopharmacology of ASD is still faced with at least two major hurdles: (a) Great interindividual variability in clinical response and side effect sensitivity is observed in the ASD population. This low level of predictability would benefit from symptom-specific treatment algorithms and from biomarkers to support drug choice; (b) To this date, no psychoactive drug appears to directly ameliorate core autism symptoms, although some indirect improvement has been reported with several drugs, once the comorbid target symptom is abated. • The pediatric psychopharmacology of ASD is systematically reviewed. • Tryciclics, neuroleptics and naltrexone were first-line treatments until the 90's. • Second generation antipsychotics and other drugs have since become first-line treatments. • Psychoactive drugs directly ameliorate co-morbid and not core ASD symptoms. • Great interindividual variability in sensitivity to therapeutic and adverse effects. [ABSTRACT FROM AUTHOR]

In recent years, findings from genetic and other biological studies are starting to reveal the role of various molecular mechanisms that contribute to the etiology of ASD. The relevance is at least twofold: on the one hand, this domain may be more directly linkable to specific and traceable neurobiological abnormalities in comparison to other ASD domains falling within the broader realm of social cognition; on the other hand, abnormal sensory processing is increasingly emerging as a relevant source of maladaptive behaviors with measurable impact on the quality of life of individuals with ASD and their families. Despite these efforts, DNA variation alone is unlikely to explain the majority of phenotypic variance, since epigenetic variation is as efficient as deletions in down-regulating expression of critical ASD genes [[41]] and the modulation of ASD gene promoter methylation is emerging as a significant cause of association between ASD and many common SNPs [[42]]. These and other studies suggest that many of the synaptic genes found to be associated with ASD are expressed prenatally and throughout early development, spatially and temporally coinciding with synaptic organization in brain regions relevant for ASD. [Extracted from the article]

Organophosphate compounds (OPs) interfere with neurodevelopment and are neurotoxic for humans and animals. They are first biotransformed to the more toxic oxon form, and then hydrolyzed to specific metabolites by the enzyme paraoxonase/arylesterase, encoded by the gene PON1 located on human chr. 7q21.3. In autism spectrum disorder (ASD) and in attention-deficit/hyperactivity disorder (ADHD), a correlation between OP exposure and disease onset has been reported. In this case-control study, we aimed to replicate our previous work showing reduced levels of serum PON1 arylesterase activity in Italian and Caucasian-American ASD samples, and to extend our analysis to other neurodevelopmental disorders, namely ADHD and developmental language disorder (DLD), also known as specific language impairment (SLI). The arylesterase activity, measured using standard spectrophotometric methods, is significantly reduced in the ADHD, and not in the ASD sample compared with the controls. Our previous results seemingly stem from spuriously high arylesterase levels in the former control sample. Finally, genotyping SNPs rs705379 and rs662 using TDI-FP, a significant effect of rs705379 alleles on the serum arylesterase activity is observed in all of the subgroups tested, regardless of diagnosis, as well as a lack of association between PON1 gene polymorphisms and ASD/ADHD susceptibility in the Italian population. In summary, the serum arylesterase activity is reduced in children and adolescents with ADHD, and this reduction is not due to the functional PON1 gene variants assessed in this study. Based on previous literature, it may more likely reflect enhanced oxidative stress than specific genetic underpinnings. [ABSTRACT FROM AUTHOR]

Background: Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social interaction/communication, stereotypic behaviors, restricted interests, and abnormal sensory-processing. Several studies have reported significantly elevated urinary and foecal levels of p-cresol in ASD children, an aromatic compound either of environmental origin or produced by specific gut bacterial strains. Methods: Since p-cresol is a known uremic toxin, able to negatively affect multiple brain functions, the present study was undertaken to assess the effects of a single acute injection of low- or high-dose (1 or 10 mg/kg i.v. respectively) of p-cresol in behavioral and neurochemical phenotypes of BTBR mice, a reliable animal model of human ASD. Results: P-cresol significantly increased anxiety-like behaviors and hyperactivity in the open field, in addition to producing stereotypic behaviors and loss of social preference in BTBR mice. Tissue levels of monoaminergic neurotransmitters and their metabolites unveiled significantly activated dopamine turnover in amygdala as well as in dorsal and ventral striatum after p-cresol administration; no effect was recorded in medial-prefrontal cortex and hippocampus. Conclusion: Our study supports a gene x environment interaction model, whereby p-cresol, acting upon a susceptible genetic background, can acutely induce autism-like behaviors and produce abnormal dopamine metabolism in the reward circuitry. [ABSTRACT FROM AUTHOR]

Investigates the linkage between a dopamine transporter marker and schizophrenia spectrum disorders. Causal relationships between genetic mutations at the dopamine transporter locus and the disease phenotype; Etiology of schizophrenia.

A response by Antonio M. Persico and colleagues to a letter to the editor about their article "Association of autism with polyomavirus infection in postmortem brain" in the 2010 issue is presented.

Background: Autism spectrum disorder (ASD) is characterized by high heritability estimates and recurrence rates; its genetic underpinnings are very heterogeneous and include variable combinations of common and rare variants. Array‐comparative genomic hybridization (aCGH) offers significant sensitivity for the identification of copy number variants (CNVs), which can act as susceptibility or causal factors for ASD. Methods: The aim of this study was to evaluate both diagnostic yield and clinical impact of aCGH in 329 ASD patients of Italian descent. Results: Pathogenic/likely pathogenic CNVs were identified in 50/329 (15.2%) patients, whereas 89/329 (27.1%) carry variants of uncertain significance. The 10 most enriched gene sets identified by Gene Ontology Enrichment Analysis are primarily involved in neuronal function and synaptic connectivity. In 13/50 (26.0%) patients with pathogenic/likely pathogenic CNVs, the outcome of array‐CGH led to the request of 25 additional medical exams which would not have otherwise been prescribed, mainly including brain MRI, EEG, EKG, and/or cardiac ultrasound. A positive outcome was obtained in 12/25 (48.0%) of these additional tests. Conclusions: This study confirms the satisfactory diagnostic yield of aCGH, underscoring its potential for better, more in‐depth care of children with autism when genetic results are analyzed also with a focus on patient management. [ABSTRACT FROM AUTHOR]

Autism spectrum disorder (ASD) is a neurodevelopmental condition with onset in early childhood, still diagnosed only through clinical observation due to the lack of laboratory biomarkers. Early detection strategies would be especially useful in screening high-risk newborn siblings of children already diagnosed with ASD. We performed RNA sequencing on peripheral blood, comparing 27 pairs of ASD children vs their sex- and age-matched unaffected siblings. Differential gene expression profiling, performed applying an unpaired model found two immune genes, EGR1 and IGKV3D-15, significantly upregulated in ASD patients (both p adj = 0.037). Weighted gene correlation network analysis identified 18 co-expressed modules. One of these modules was downregulated among autistic individuals (p = 0.035) and a ROC curve using its eigengene values yielded an AUC of 0.62. Genes in this module are primarily involved in transcriptional control and its hub gene, RACK1, encodes for a signaling protein critical for neurodevelopment and innate immunity, whose expression is influenced by various hormones and known "endocrine disruptors". These results indicate that transcriptomic biomarkers can contribute to the sensitivity of an intra-familial multimarker panel for ASD and provide further evidence that neurodevelopment, innate immunity and transcriptional regulation are key to ASD pathogenesis. [ABSTRACT FROM AUTHOR]

Macrocephaly and brain overgrowth have been associated with autism spectrum disorder. We performed a systematic review and meta-analysis to provide an overall estimate of effect size and statistical significance for both head circumference and total brain volume in autism. Our literature search strategy identified 261 and 391 records, respectively; 27 studies defining percentages of macrocephalic patients and 44 structural brain imaging studies providing total brain volumes for patients and controls were included in our meta-analyses. Head circumference was significantly larger in autistic compared to control individuals, with 822/5225 (15.7%) autistic individuals displaying macrocephaly. Structural brain imaging studies measuring brain volume estimated effect size. The effect size is higher in low functioning autistics compared to high functioning and ASD individuals. Brain overgrowth was recorded in 142/1558 (9.1%) autistic patients. Finally, we found a significant interaction between age and total brain volume, resulting in larger head circumference and brain size during early childhood. Our results provide conclusive effect sizes and prevalence rates for macrocephaly and brain overgrowth in autism, confirm the variation of abnormal brain growth with age, and support the inclusion of this endophenotype in multi-biomarker diagnostic panels for clinical use. [ABSTRACT FROM AUTHOR]

Background: Autism spectrum disorder (ASD) is a neurodevelopmental disorder with strong genetic underpinnings. Microarray‐based comparative genomic hybridization (aCGH) technology has been proposed as a first‐level test in the genetic diagnosis of ASD and of neurodevelopmental disorders in general. Methods: We performed aCGH on 98 Tunisian children (83 boys and 15 girls) diagnosed with ASD according to DSM‐IV criteria. Results: "Pathogenic" or "likely pathogenic" copy number variants (CNVs) were detected in 11 (11.2%) patients, CNVs of "uncertain clinical significance" in 26 (26.5%), "likely benign" or "benign" CNVs were found in 37 (37.8%) and 24 (24.5%) patients, respectively. Gene set enrichment analysis involving genes spanning rare "pathogenic," "likely pathogenic," or "uncertain clinical significance" CNVs, as well as SFARI database "autism genes" in common CNVs, detected eight neuronal Gene Ontology classes among the top 10 most significant, including synapse, neuron differentiation, synaptic signaling, neurogenesis, and others. Similar results were obtained performing g: Profiler analysis. Neither transcriptional regulation nor immune pathways reached significance. Conclusions: aCGH confirms its sizable diagnostic yield in a novel sample of autistic children from North Africa. Recruitment of additional families is under way, to verify whether genetic contributions to ASD in the Tunisian population, differently from other ethnic groups, may involve primarily neuronal genes, more than transcriptional regulation and immune‐related pathways. [ABSTRACT FROM AUTHOR]

Background: Understanding the development of the neuronal circuitry underlying autism spectrum disorder (ASD) is critical to shed light into its etiology and for the development of treatment options. Resting state EEG provides a window into spontaneous local and long-range neuronal synchronization and has been investigated in many ASD studies, but results are inconsistent. Unbiased investigation in large and comprehensive samples focusing on replicability is needed. Methods: We quantified resting state EEG alpha peak metrics, power spectrum (PS, 2–32 Hz) and functional connectivity (FC) in 411 children, adolescents and adults (n = 212 ASD, n = 199 neurotypicals [NT], all with IQ > 75). We performed analyses in source-space using individual head models derived from the participants' MRIs. We tested for differences in mean and variance between the ASD and NT groups for both PS and FC using linear mixed effects models accounting for age, sex, IQ and site effects. Then, we used machine learning to assess whether a multivariate combination of EEG features could better separate ASD and NT participants. All analyses were embedded within a train-validation approach (70%–30% split). Results: In the training dataset, we found an interaction between age and group for the reactivity to eye opening (p =.042 uncorrected), and a significant but weak multivariate ASD vs. NT classification performance for PS and FC (sensitivity 0.52–0.62, specificity 0.59–0.73). None of these findings replicated significantly in the validation dataset, although the effect size in the validation dataset overlapped with the prediction interval from the training dataset. Limitations: The statistical power to detect weak effects—of the magnitude of those found in the training dataset—in the validation dataset is small, and we cannot fully conclude on the reproducibility of the training dataset's effects. Conclusions: This suggests that PS and FC values in ASD and NT have a strong overlap, and that differences between both groups (in both mean and variance) have, at best, a small effect size. Larger studies would be needed to investigate and replicate such potential effects. [ABSTRACT FROM AUTHOR]

Elevated blood serotonin (5-HT) levels were the first biomarker identified in autism research. Many studies have contrasted blood 5-HT levels in autistic patients and controls, but different measurement protocols, technologies, and biomaterials have been used through the years. We performed a systematic review and meta-analysis to provide an overall estimate of effect size and between-study heterogeneity, while verifying whether and to what extent different methodological approaches influence the strength of this association. Our literature search strategy identified 551 papers, from which 22 studies providing patient and control blood 5-HT values were selected for meta-analysis. Significantly higher 5-HT levels in autistic patients compared to controls were recorded both in whole blood (WB) [O.R.=4.6; (3.1–5.2); P=1.0×10−12], and in platelet-rich plasma (PRP) [O.R.=2.6 (1.8–3.9); P=2.7×10−7]. Predictably, studies measuring 5-HT levels in platelet-poor plasma (PPP) yielded no significant group difference [O.R.=0.54 (0.2–2–0); P=0.36]. Altogether, elevated 5-HT blood levels were recorded in 28.3% in WB and 22.5% in PRP samples of autistic individuals, as reported in 15 and 4 studies, respectively. Studies employing HPLC vs fluorometric assays yield similar cumulative effect sizes, but the former display much lower variability. In summary, despite some limitations mainly due to small study sample sizes, our results significantly reinforce the reliability of elevated 5-HT blood levels as a biomarker in ASD, providing practical indications potentially useful for its inclusion in multi-marker diagnostic panels for clinical use. [ABSTRACT FROM AUTHOR]