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1.  Increased IgG4 levels in children with autism disorder 
Brain, behavior, and immunity  2008;23(3):389-395.
Accumulating evidence indicates that immune dysfunction is associated with autism disorders in a significant subset of children. Previous reports have shown abnormal immunoglobulin (Ig) levels, including an increased presence of autoreactive antibodies in the circulation of individuals with autism. As IgG is the predominant antibody isotype in circulation, we expected that an altered immune response could result in an abnormal IgG subclass profile in children with autism. We examined circulating plasma levels of IgG1, IgG2, IgG3, and IgG4 in 241 children from the CHARGE (Childhood Autism Risks from Genetics and the Environment) study, a large epidemiologic case-control investigation, including 114 children who meet full criteria for autism disorder (AU), 96 typically developing control children (TD) from a randomly selected sample of the general population, and 31 children with developmental delays (DD). We report significantly increased levels of the IgG4 subclass in children with AU compared with TD control children (p=0.016) and compared with DD controls (p=0.041). These results may suggest an underlying immunological abnormality in AU subjects resulting in elevated IgG4 production. Further investigation is necessary to elucidate the relationship between immunological findings and behavioral impairments in autism.
doi:10.1016/j.bbi.2008.12.005
PMCID: PMC2696343  PMID: 19136055
2.  Consensus Paper: Pathological Role of the Cerebellum in Autism 
Cerebellum (London, England)  2012;11(3):777-807.
There has been significant advancement in various aspects of scientific knowledge concerning the role of cerebellum in the etiopathogenesis of autism. In the current consensus paper, we will observe the diversity of opinions regarding the involvement of this important site in the pathology of autism. Recent emergent findings in literature related to cerebellar involvement in autism are discussed, including: cerebellar pathology, cerebellar imaging and symptom expression in autism, cerebellar genetics, cerebellar immune function, oxidative stress and mitochondrial dysfunction, GABAergic and glutamatergic systems, cholinergic, dopaminergic, serotonergic, and oxytocin related changes in autism, motor control and cognitive deficits, cerebellar coordination of movements and cognition, gene-environment interactions, therapeutics in autism and relevant animal models of autism. Points of consensus include presence of abnormal cerebellar anatomy, abnormal neurotransmitter systems, oxidative stress, cerebellar motor and cognitive deficits, and neuroinflammation in subjects with autism. Undefined areas or areas requiring further investigation include lack of treatment options for core symptoms of autism, vermal hypoplasia and other vermal abnormalities as a consistent feature of autism, mechanisms underlying cerebellar contributions to cognition, and unknown mechanisms underlying neuroinflammation.
doi:10.1007/s12311-012-0355-9
PMCID: PMC3677555  PMID: 22370873
cerebellum; autism
3.  Environmental Factors in Autism 
Autism is a neurodevelopmental disorders characterized by impairments in communication and social behavior, and by repetitive behaviors. Although genetic factors might be largely responsible for the occurrence of autism they cannot fully account for all cases and it is likely that in addition to a certain combination of autism-related genes, specific environmental factors might act as risk factors triggering the development of autism. Thus, the role of environmental factors in autism is an important area of research and recent data will be discussed in this review. Interestingly, the results show that many environmental risk factors are interrelated and their identification and comparison might unveil a common scheme of alterations on a contextual as well as molecular level. For example, both, disruption in the immune system and in zinc homeostasis may affect synaptic transmission in autism. Thus, here, a model is proposed that interconnects the most important and scientifically recognized environmental factors. Moreover, similarities in how these risk factors impact synapse function are discussed and a possible influence on an already well described genetic pathway leading to the development of autism via zinc homeostasis is proposed.
doi:10.3389/fpsyt.2012.00118
PMCID: PMC3548163  PMID: 23346059
zinc deficiency; immune system; cytokines; ASD; Shank3; melatonin; risk factor
4.  Adaptive and Innate Immune Responses in Autism: Rationale for Therapeutic Use of Intravenous Immunoglobulin 
Journal of Clinical Immunology  2010;30(Suppl 1):90-96.
Background
Autism is a complex polygenic neurodevelopmental disorder characterized by deficits in communication and social interactions as well as specific stereotypical behaviors. Both genetic and environmental factors appear to contribute to the pathogenesis of autism. Accumulating data including changes in immune responses, linkage to major histocompatibility complex antigens, and the presence of autoantibodies to neural tissues/antigens suggest that the immune system plays an important role in its pathogenesis.
Summary
In this brief review, we discuss the data regarding changes in both innate and adaptive immunity in autism and the evidence in favor of the role of the immune system, especially of maternal autoantibodies in the pathogenesis of a subset of patients with autism. The rationale for possible therapeutic use of intravenous immunoglobulin is also discussed.
doi:10.1007/s10875-010-9402-9
PMCID: PMC2883089  PMID: 19898927
Cytokines; chemokines; autoantibodies; dendritic cells; CVID; lymphocyte subsets; IVIG; IgG; IgG subclasses
5.  Use of Artificial Intelligence to Shorten the Behavioral Diagnosis of Autism 
PLoS ONE  2012;7(8):e43855.
The Autism Diagnostic Interview-Revised (ADI-R) is one of the most commonly used instruments for assisting in the behavioral diagnosis of autism. The exam consists of 93 questions that must be answered by a care provider within a focused session that often spans 2.5 hours. We used machine learning techniques to study the complete sets of answers to the ADI-R available at the Autism Genetic Research Exchange (AGRE) for 891 individuals diagnosed with autism and 75 individuals who did not meet the criteria for an autism diagnosis. Our analysis showed that 7 of the 93 items contained in the ADI-R were sufficient to classify autism with 99.9% statistical accuracy. We further tested the accuracy of this 7-question classifier against complete sets of answers from two independent sources, a collection of 1654 individuals with autism from the Simons Foundation and a collection of 322 individuals with autism from the Boston Autism Consortium. In both cases, our classifier performed with nearly 100% statistical accuracy, properly categorizing all but one of the individuals from these two resources who previously had been diagnosed with autism through the standard ADI-R. Our ability to measure specificity was limited by the small numbers of non-spectrum cases in the research data used, however, both real and simulated data demonstrated a range in specificity from 99% to 93.8%. With incidence rates rising, the capacity to diagnose autism quickly and effectively requires careful design of behavioral assessment methods. Ours is an initial attempt to retrospectively analyze large data repositories to derive an accurate, but significantly abbreviated approach that may be used for rapid detection and clinical prioritization of individuals likely to have an autism spectrum disorder. Such a tool could assist in streamlining the clinical diagnostic process overall, leading to faster screening and earlier treatment of individuals with autism.
doi:10.1371/journal.pone.0043855
PMCID: PMC3428277  PMID: 22952789
6.  Autism risk assessment in siblings of affected children using sex-specific genetic scores 
Molecular Autism  2011;2:17.
Background
The inheritance pattern in most cases of autism is complex. The risk of autism is increased in siblings of children with autism and previous studies have indicated that the level of risk can be further identified by the accumulation of multiple susceptibility single nucleotide polymorphisms (SNPs) allowing for the identification of a higher-risk subgroup among siblings. As a result of the sex difference in the prevalence of autism, we explored the potential for identifying sex-specific autism susceptibility SNPs in siblings of children with autism and the ability to develop a sex-specific risk assessment genetic scoring system.
Methods
SNPs were chosen from genes known to be associated with autism. These markers were evaluated using an exploratory sample of 480 families from the Autism Genetic Resource Exchange (AGRE) repository. A reproducibility index (RI) was proposed and calculated in all children with autism and in males and females separately. Differing genetic scoring models were then constructed to develop a sex-specific genetic score model designed to identify individuals with a higher risk of autism. The ability of the genetic scores to identify high-risk children was then evaluated and replicated in an independent sample of 351 affected and 90 unaffected siblings from families with at least 1 child with autism.
Results
We identified three risk SNPs that had a high RI in males, two SNPs with a high RI in females, and three SNPs with a high RI in both sexes. Using these results, genetic scoring models for males and females were developed which demonstrated a significant association with autism (P = 2.2 × 10-6 and 1.9 × 10-5, respectively).
Conclusions
Our results demonstrate that individual susceptibility associated SNPs for autism may have important differential sex effects. We also show that a sex-specific risk score based on the presence of multiple susceptibility associated SNPs allow for the identification of subgroups of siblings of children with autism who have a significantly higher risk of autism.
doi:10.1186/2040-2392-2-17
PMCID: PMC3214848  PMID: 22017886
Autism; risk assessment; common variants; genetic score; sex effects
7.  HLA Immune Function Genes in Autism 
Autism Research and Treatment  2012;2012:959073.
The human leukocyte antigen (HLA) genes on chromosome 6 are instrumental in many innate and adaptive immune responses. The HLA genes/haplotypes can also be involved in immune dysfunction and autoimmune diseases. It is now becoming apparent that many of the non-antigen-presenting HLA genes make significant contributions to autoimmune diseases. Interestingly, it has been reported that autism subjects often have associations with HLA genes/haplotypes, suggesting an underlying dysregulation of the immune system mediated by HLA genes. Genetic studies have only succeeded in identifying autism-causing genes in a small number of subjects suggesting that the genome has not been adequately interrogated. Close examination of the HLA region in autism has been relatively ignored, largely due to extraordinary genetic complexity. It is our proposition that genetic polymorphisms in the HLA region, especially in the non-antigen-presenting regions, may be important in the etiology of autism in certain subjects.
doi:10.1155/2012/959073
PMCID: PMC3420779  PMID: 22928105
8.  Genome-wide Linkage Analyses of Quantitative and Categorical Autism Subphenotypes 
Biological Psychiatry  2008;64(7):561-570.
Background
The search for susceptibility genes in autism and autism spectrum disorders (ASD) has been hindered by the possible small effects of individual genes and by genetic (locus) heterogeneity. To overcome these obstacles, one method is to use autism-related subphenotypes instead of the categorical diagnosis of autism since they may be more directly related to the underlying susceptibility loci. Another strategy is to analyze subsets of families that meet certain clinical criteria to reduce genetic heterogeneity.
Methods
In this study, using 976 multiplex families from the Autism Genome Project consortium, we performed genome-wide linkage analyses on two quantitative subphenotypes, the total scores of the reciprocal social interaction domain and the restricted, repetitive, and stereotyped patterns of behavior domain from the Autism Diagnostic Interview-Revised. We also selected subsets of ASD families based on four binary subphenotypes, delayed onset of first words, delayed onset of first phrases, verbal status, and IQ ≥ 70.
Results
When the ASD families with IQ ≥ 70 were used, a logarithm of odds (LOD) score of 4.01 was obtained on chromosome 15q13.3-q14, which was previously linked to schizophrenia. We also obtained a LOD score of 3.40 on chromosome 11p15.4-p15.3 using the ASD families with delayed onset of first phrases. No significant evidence for linkage was obtained for the two quantitative traits.
Conclusions
This study demonstrates that selection of informative subphenotypes to define a homogeneous set of ASD families could be very important in detecting the susceptibility loci in autism.
doi:10.1016/j.biopsych.2008.05.023
PMCID: PMC2670970  PMID: 18632090
Autism; genetic heterogeneity; IQ; language; linkage analysis; schizophrenia
9.  Immune system gene dysregulation in autism & schizophrenia 
Developmental neurobiology  2012;72(10):1277-1287.
Gene*environment interactions play critical roles in the emergence of autism and schizophrenia pathophysiology. In both disorders, recent genetic association studies have provided evidence for disease-linked variation in immune system genes and post-mortem gene expression studies have shown extensive chronic immune abnormalities in brains of diseased subjects. Furthermore, peripheral biomarker studies revealed that both innate and adaptive immune systems are dysregulated. In both disorders symptoms of the disease correlate with the immune system dysfunction; yet, in autism this process appears to be chronic and sustained, while in schizophrenia it is exacerbated during acute episodes. Furthermore, since immune abnormalities endure into adulthood and anti-inflammatory agents appear to be beneficial, it is likely that these immune changes actively contribute to disease symptoms. Modeling these changes in animals provided further evidence that prenatal maternal immune activation alters neurodevelopment and leads to behavioral changes that are relevant for autism and schizophrenia. The converging evidence strongly argues that neurodevelopmental immune insults and genetic background critically interact and result in increased risk for either autism or schizophrenia. Further research in these areas may improve prenatal health screening in genetically at-risk families and may also lead to new preventive and/or therapeutic strategies.
doi:10.1002/dneu.22044
PMCID: PMC3435446  PMID: 22753382
schizophrenia; autism; immune; environment; maternal immune activation
10.  Immunologic and Neurodevelopmental Susceptibilities of Autism 
Neurotoxicology  2008;29(3):531-544.
Symposium 5 focused on research approaches that are aimed at understanding common patterns of immunological and neurological dysfunction contributing to neurodevelopmental disorders such as autism and ADHD. The session focused on genetic, epigenetic, and environmental factors that might act in concert to influence autism risk, severity and co-morbidities, and immunological and neurobiological targets as etiologic contributors. The immune system of children at risk of autism may be therefore especially susceptible to psychological stressors, exposure to chemical triggers, and infectious agents. Identifying early biomarkers of risk provides tangible approaches toward designing studies in animals and humans that yield a better understanding of environmental risk factors, and can help identify rational intervention strategies to mitigate these risks.
doi:10.1016/j.neuro.2008.02.006
PMCID: PMC2475601  PMID: 18394707
11.  Reduced Levels of Immunoglobulin in Children With Autism Correlates With Behavioral Symptoms 
Objectives
To assay if plasma antibody levels in children with autism or developmental delays (DD) differ from those with typical development as an indicator of immune function and to correlate antibody levels with severity of behavioral symptoms.
Methods
Plasma was collected from children with autistic disorder (AU; n=116), DD but not autism (n=32), autism spectrum disorder but not full autism (n=27), and age-matched typically developing (TD) controls (n=96). Samples were assayed for systemic levels of immunoglobulin (IgG, IgM, IgA, and IgE) by enzyme-linked immunosorbent assay. Subjects with autism were evaluated using the Autism Diagnostic Observation Schedule and the Autism Diagnostic Interview—Revised, and all subjects were scored on the Aberrant Behavior Checklist (ABC) by the parents. Numerical scores for each of the ABC subscales as well as the total scores were then correlated with Ig levels.
Results
Children with AU have a significantly reduced level of plasma IgG (5.39±0.29 mg/mL) compared to the TD (7.72±0.28 mg/mL; P<0.001) and DD children (8.23±0.49 mg/mL; P<0.001). Children with autism also had a reduced level of plasma IgM (0.670.06mg/mL) compared to TD (0.79±0.05 mg/mL; P<0.05). Ig levels were negatively correlated with ABC scores for all children (IgG: r=−0.334, P<0.0001; IgM: r=−0.167, P=0.0285).
Conclusion
Children with AU have significantly reduced levels of plasma IgG and IgM compared to both DD and TD controls, suggesting an underlying defect in immune function. This reduction in specific Ig levels correlates with behavioral severity, where those patients with the highest scores in the behavioral battery have the most reduced levels of IgG and IgM.
doi:10.1002/aur.42
PMCID: PMC2663897  PMID: 19343198
Autism; immunoglobulin; behavior; IgG
12.  The Immune System’s Role in the Biology of Autism 
Current opinion in neurology  2010;23(2):111-117.
PURPOSE OF REVIEW
The following is a review of the most recent research concerning the potential role of immune system dysfunction in autism. This body of literature has expanded dramatically over the past few years as researchers continue to identify immune anomalies in individuals with autism.
RECENT FINDINGS
The most exciting of these recent findings is the discovery of autoantibodies targeting brain proteins in both children with autism and their mothers. In particular, circulating maternal autoantibodies directed towards fetal brain proteins are highly specific for autism. This finding has great potential as a biomarker for disease risk, and may provide an avenue for future therapeutics and prevention. Additionally, data concerning the cellular immune system in children with autism suggest there may be a defect in signaling pathways that are shared by the immune and central nervous systems. While studies to explore this hypothesis are ongoing, there is great interest in the commonalities between the neural and immune systems and their extensive interactions.
SUMMARY
In summary, there is exciting research regarding the role of the immune system in autism spectrum disorders that may have profound implications for diagnosis and treatment of this devastating disease.
doi:10.1097/WCO.0b013e3283373514
PMCID: PMC2898160  PMID: 20160651
Immune system; autoantibodies; immunoglobulin; cytokines; autism
13.  Etiology of infantile autism: a review of recent advances in genetic and neurobiological research. 
The etiology of autism is complex, and in most cases the underlying pathologic mechanisms are unknown. Autism is a hetereogeneous disorder, diagnosed subjectively on the basis of a large number of criteria. Recent research has investigated genetics, in utero insults and brain function as well as neurochemical and immunological factors. On the basis of family and twin studies, there appears to be a genetic basis for a wide "autistic syndrome." About a quarter of cases of autism are associated with genetic disorders such as fragile X syndrome or with infectious diseases such as congenital rubella. Genetic studies have shown an association between autism markers of brain development such as 3 markers of the c-Harvey-ros oncogene and the homeobox gene EN2. In some cases, autism is associated with insults early in gestation, including thalidomide embryopathy. Autism may arise from abnormal central nervous system functioning, since most autistic patients have indications of brain dysfunction, and about half of them have abnormal electroencephalograms. Similarly, the pattern of evoked response potentials and conduction time is altered in autistic children. There is substantial evidence from neuroimaging studies that dysfunctions in the cerebellum and possibly the temporal lobe and association cortex occur in autistic symptoms. Neurochemical studies have investigated the role of serotonin, epinephrine and norepinephrine, since levels of these neurotransmitters are altered in autism, although other hypotheses implicate overactive brain opioid systems and changes in oxytocin neurotransmission. Autoimmunity may also play a role; antibodies against myelin basic protein are often found in children with autism, who also have increased eosinophil and basophil response to IgE-mediated reactions. In summary, the prevailing view is that autism is caused by a pathophysiologic process arising from the interaction of an early environmental insult and a genetic predisposition.
PMCID: PMC1188990  PMID: 10212552
14.  Is Autism a Member of a Family of Diseases Resulting from Genetic/Cultural Mismatches? Implications for Treatment and Prevention 
Autism Research and Treatment  2012;2012:910946.
Several lines of evidence support the view that autism is a typical member of a large family of immune-related, noninfectious, chronic diseases associated with postindustrial society. This family of diseases includes a wide range of inflammatory, allergic, and autoimmune diseases and results from consequences of genetic/culture mismatches which profoundly destabilize the immune system. Principle among these consequences is depletion of important components, particularly helminths, from the ecosystem of the human body, the human biome. Autism shares a wide range of features in common with this family of diseases, including the contribution of genetics/epigenetics, the identification of disease-inducing triggers, the apparent role of immunity in pathogenesis, high prevalence, complex etiologies and manifestations, and potentially some aspects of epidemiology. Fortunately, using available resources and technology, modern medicine has the potential to effectively reconstitute the human biome, thus treating or even avoiding altogether the consequences of genetic/cultural mismatches which underpin this entire family of disease. Thus, if indeed autism is an epidemic of postindustrial society associated with immune hypersensitivity, we can expect that the disease is readily preventable.
doi:10.1155/2012/910946
PMCID: PMC3420574  PMID: 22928103
15.  Childhood autism in a 13 year old boy with oculocutaneous albinism: a case report 
Introduction
Hypomelanotic skin disorders like tuberous sclerosis and hypomelanosis of Ito that present with multiple systemic manifestations have been reported in association with childhood autism. Oculocutaneous albinism is another hypomelanotic skin disorder that rarely presents with multiple systemic manifestations. It is infrequently reported in association with childhood autism when compared to tuberous sclerosis and hypomelanosis of Ito.
Case presentation
This article reports a case of co-morbid childhood autism and oculocutaneous albinism in a 13-year old boy from Nigeria in Sub-Saharan Africa.
Conclusion
The observation in this case report and in two previous reports which documented association between oculocutaneous albinism and childhood autism both in the affected individuals and families of individuals with childhood autism, raises the question of a possible genetic and clinical association between oculocutaneous albinism and childhood autism. More family and genetic studies into the relationship between oculocutaneous albinism and childhood autism is desirable. This may provide useful clues into the etiology, prevention and management of childhood autism as well as oculocutaneous albinism.
doi:10.1186/1752-1947-2-56
PMCID: PMC2265727  PMID: 18294379
16.  Rapid Automatized Naming as an Index of Genetic Liability to Autism 
This study investigated rapid automatized naming (RAN) ability in high functioning individuals with autism and parents of individuals with autism. Findings revealed parallel patterns of performance in parents and individuals with autism, where both groups had longer naming times than controls. Significant parent-child correlations were also detected, along with associations with language and personality features of the broad autism phenotype (retrospective reports of early language delay, socially reticent personality). Together, findings point towards RAN as a potential marker of genetic liability to autism.
doi:10.1007/s11689-010-9045-4
PMCID: PMC2922764  PMID: 20721307
17.  Rapid automatized naming as an index of genetic liability to autism 
This study investigated rapid automatized naming (RAN) ability in high functioning individuals with autism and parents of individuals with autism. Findings revealed parallel patterns of performance in parents and individuals with autism, where both groups had longer naming times than controls. Significant parent-child correlations were also detected, along with associations with language and personality features of the broad autism phenotype (retrospective reports of early language delay, socially reticent personality). Together, findings point towards RAN as a potential marker of genetic liability to autism.
doi:10.1007/s11689-010-9045-4
PMCID: PMC2922764  PMID: 20721307
Autism; Rapid automatized naming; Endophenotype; Broad autism phenotype
18.  Above genetics: lessons from cerebral development in autism 
Translational neuroscience  2011;2(2):106-120.
While a distinct minicolumnar phenotype seems to be an underlying factor in a significant portion of cases of autism, great attention is being paid not only to genetics but to epigenetic factors which may lead to development of the conditions. Here we discuss the indivisible role the molecular environment plays in cellular function, particularly the pivotal position which the transcription factor and adhesion molecule, β-catenin, occupies in cellular growth. In addition, the learning environment is not only integral to postnatal plasticity, but the prenatal environment plays a vital role during corticogenesis, neuritogenesis, and synaptogenesis as well. To illustrate these points in the case of autism, we review important findings in genetics studies (e.g., PTEN, TSC1/2, FMRP, MeCP2, Neurexin-Neuroligin) and known epigenetic factors (e.g., valproic acid, estrogen, immune system, ultrasound) which may predispose towards the minicolumnar and connectivity patterns seen in the conditions, showing how one-gene mutational syndromes and exposure to certain CNS teratogens may ultimately lead to comparable phenotypes. This in turn may shed greater light on how environment and complex genetics combinatorially give rise to a heterogenetic group of conditions such as autism.
doi:10.2478/s13380-011-0016-3
PMCID: PMC3331673  PMID: 22523638
beta catenin; minicolumns; neural stem cells; Rett syndrome; fragile X syndrome; tuberous sclerosis; valproic acid; PTEN phosphohydrolase; ultrasonography; cell adhesion molecules; neuronal
19.  Modeling Autistic Features in Animals 
Pediatric research  2011;69(5 Pt 2):34R-40R.
A variety of features of autism can be simulated in rodents, including the core behavioral hallmarks of stereotyped and repetitive behaviors, and deficits in social interaction and communication. Other behaviors frequently found in autism spectrum disorders (ASD) such as neophobia, enhanced anxiety, abnormal pain sensitivity and eye blink conditioning, disturbed sleep patterns, seizures, and deficits in sensorimotor gating are also present in some of the animal models. Neuropathology and some characteristic neurochemical changes that are frequently seen in autism, as well as alterations in the immune status in the brain and periphery are also found in some of the models. Several known environmental risk factors for autism have been successfully established in rodents, including maternal infection and maternal valproate administration. Also under investigation are a number of mouse models based on genetic variants associated with autism or on syndromic disorders with autistic features. This review briefly summarizes recent developments in this field, highlighting models with face and/or construct validity, and noting the potential for investigation of pathogenesis and early progress towards clinical testing of potential therapeutics. Wherever possible, reference is made to reviews rather than primary articles.
doi:10.1203/PDR.0b013e318212b80f
PMCID: PMC3088489  PMID: 21289542
20.  Investigation of autism and GABA receptor subunit genes in multiple ethnic groups 
Neurogenetics  2006;7(3):167-174.
Autism is a neurodevelopmental disorder of complex genetics, characterized by impairment in social interaction and communication, as well as repetitive behavior. Multiple lines of evidence, including alterations in levels of GABA and GABA receptors in autistic patients, indicate that the GABAergic system, which is responsible for synaptic inhibition in the adult brain, may be involved in autism. Previous studies in our lab indicated association of noncoding single nucleotide polymorphisms (SNPs) within a GABA receptor subunit gene on chromosome 4, GABRA4, and interaction between SNPs in GABRA4 and GABRB1 (also on chromosome 4), within Caucasian autism patients. Studies of genetic variation in African-American autism families are rare. Analysis of 557 Caucasian and an independent population of 54 African-American families with 35 SNPs within GABRB1 and GABRA4 strengthened the evidence for involvement of GABRA4 in autism risk in Caucasians (rs17599165, p=0.0015; rs1912960, p=0.0073; and rs17599416, p=0.0040) and gave evidence of significant association in African-Americans (rs2280073, p=0.0287 and rs16859788, p=0.0253). The GABRA4 and GABRB1 interaction was also confirmed in the Caucasian dataset (most significant pair, rs1912960 and rs2351299; p=0.004). Analysis of the subset of families with a positive history of seizure activity in at least one autism patient revealed no association to GABRA4; however, three SNPs within GABRB1 showed significant allelic association; rs2351299 (p=0.0163), rs4482737 (p=0.0339), and rs3832300 (p=0.0253). These results confirmed our earlier findings, indicating GABRA4 and GABRB1 as genes contributing to autism susceptibility, extending the effect to multiple ethnic groups and suggesting seizures as a stratifying phenotype.
doi:10.1007/s10048-006-0045-1
PMCID: PMC1513515  PMID: 16770606
Autism; SNPs; GABA receptors; Association; Ethnicity
21.  Convergent synaptic and circuit substrates underlying autism genetic risks 
Frontiers in biology  2014;9(2):137-150.
There has been a surge of diagnosis of autism spectrum disorders (ASD) over the past decade. While large, high powered genome screening studies of children with ASD have identified numerous genetic risk factors, research efforts to understanding how each of these risk factors contributes to the development autism has met with limited success. Revealing the mechanisms by which these genetic risk factors affect brain development and predispose a child to autism requires mechanistic understanding of the neurobiological changes underlying this devastating group of developmental disorders at multifaceted molecular, cellular and system levels. It has been increasingly clear that the normal trajectory of neurodevelopment is compromised in autism, in multiple domains as much as aberrant neuronal production, growth, functional maturation, patterned connectivity, and balanced excitation and inhibition of brain networks. Many autism risk factors identified in humans have been now reconstituted in experimental mouse models to allow mechanistic interrogation of the biological role of the risk gene. Studies utilizing these mouse models have revealed that underlying the enormous heterogeneity of perturbed cellular events, mechanisms directing synaptic and circuit assembly may provide a unifying explanation for the pathophysiological changes and behavioral endophenotypes seen in autism, although synaptic perturbations are far from being the only alterations relevant for ASD. In this review, we discuss synaptic and circuit abnormalities obtained from several prevalent mouse models, particularly those reflecting syndromic forms of ASD that are caused by single gene perturbations. These compiled results reveal that ASD risk genes contribute to proper signaling of the developing gene networks that maintain synaptic and circuit homeostasis, which is fundamental to normal brain development.
doi:10.1007/s11515-014-1298-y
PMCID: PMC4079081
autism spectrum disorders; development; risk genes; synapse; circuits; behavior; neurodevelopmental disorders
22.  Animal models of autism spectrum disorders: Information for neurotoxicologists 
Neurotoxicology  2009;30(5):811-821.
Recent findings derived from large-scale datasets and biobanks link multiple genes to autism spectrum disorders. Consequently, novel rodent mutants with deletions, truncations and in some cases, overexpression of these candidate genes have been developed and studied both behaviorally and biologically. At the Annual Neurotoxicology Meeting in Rochester, NY in October of 2008, a symposium of clinicians and basic scientists gathered to present the behavioral features of autism, as well as strategies to model those behavioral features in mice and primates. The aim of the symposium was to provide researchers with up-to-date information on both the genetics of autism and how they are used in differing in vivo and in vitro animal models as well as to provide a background on the environmental exposures being tested on several animal models. In addition, researchers utilizing complementary approaches, presented on cell culture, in vitro or more basic models, which target neurobiological mechanisms, including Drosophila. Following the presentation, a panel convened to explore the opportunities and challenges of using model systems to investigate genetic and environment interactions in autism spectrum disorders. The following paper represents a summary of each presentation, as well as the discussion that followed at the end of the symposium.
doi:10.1016/j.neuro.2009.07.002
PMCID: PMC3014989  PMID: 19596370
Animal models; Autism; Neurotoxicology; Symposium
23.  Is fever suppression involved in the etiology of autism and neurodevelopmental disorders? 
BMC Pediatrics  2003;3:9.
Background
There appears to be a significant increase in the prevalence rate of autism. Reasons for the increase are unknown, however, there is a substantial body of evidence that suggests the etiology involves infections of the pregnant mother or of a young child. Most infections result in fever that is routinely controlled with antipyretics such as acetaminophen. The blocking of fever inhibits processes that evolved over millions of years to protect against microbial attack. Immune mechanisms in the central nervous system are part of this protective process.
Hypothesis
The blockage of fever with antipyretics interferes with normal immunological development in the brain leading to neurodevelopmental disorders such as autism in certain genetically and immunologically disposed individuals.
Testing the hypothesis
Epidemiological studies to determine associations between the use of antipyretics and neurodevelopmental disorders should be undertaken. Biochemical tests will involve the examination of fluids/serum by mass spectrometry and the determination of cytokine/chemokine levels in serum and cell culture fluids after stimulation with fever-inducing molecules from bacteria, viruses and yeast. Postmortem brain can be examined by immunohistochemistry or other methods such as fluorescent in situ hybridization (FISH) to determine altered expression levels of chemokines/cytokines and other molecules.
Implications of the hypothesis
1) The use of antipyretics during pregnancy or in young children may be reserved for more severe fevers. 2) The perplexing genetic findings in autism may be better understood by categorizing genes along functional pathways. 3) New treatments based on immune, cell, pharmacological or even heat therapies may be developed.
doi:10.1186/1471-2431-3-9
PMCID: PMC194752  PMID: 12952554
24.  Association of autism with polymorphisms in the paired-like homeodomain transcription factor 1 (PITX1) on chromosome 5q31: a candidate gene analysis 
BMC Medical Genetics  2007;8:74.
Background
Autism is a complex, heterogeneous, behaviorally-defined disorder characterized by disruptions of the nervous system and of other systems such as the pituitary-hypothalamic axis. In a previous genome wide screen, we reported linkage of autism with a 1.2 Megabase interval on chromosome 5q31. For the current study, we hypothesized that 3 of the genes in this region could be involved in the development of autism: 1) paired-like homeodomain transcription factor 1 (PITX1), which is a key regulator of hormones within the pituitary-hypothalamic axis, 2) neurogenin 1, a transcription factor involved in neurogenesis, and 3) histone family member Y (H2AFY), which is involved in X-chromosome inactivation in females and could explain the 4:1 male:female gender distortion present in autism.
Methods
A total of 276 families from the Autism Genetic Resource Exchange (AGRE) repository composed of 1086 individuals including 530 affected children were included in the study. Single nucleotide polymorphisms tagging the three candidate genes were genotyped on the initial linkage sample of 116 families. A second step of analysis was performed using tightly linked SNPs covering the PITX1 gene. Association was evaluated using the FBAT software version 1.7.3 for single SNP analysis and the HBAT command from the same package for haplotype analysis respectively.
Results
Association between SNPs and autism was only detected for PITX1. Haplotype analysis within PITX1 showed evidence for overtransmission of the A-C haplotype of markers rs11959298 – rs6596189 (p = 0.0004). Individuals homozygous or heterozygous for the A-C haplotype risk allele were 2.54 and 1.59 fold more likely to be autistic than individuals who were not carrying the allele, respectively.
Conclusion
Strong and consistent association was observed between a 2 SNPs within PITX1 and autism. Our data suggest that PITX1, a key regulator of hormones within the pituitary-hypothalamic axis, may be implicated in the etiology of autism.
doi:10.1186/1471-2350-8-74
PMCID: PMC2222245  PMID: 18053270
25.  The reach-to-grasp movement in children with autism spectrum disorder. 
Autism is associated with a wide and complex array of neurobehavioural symptoms. Examination of the motor system offers a particularly appealing method for studying autism by providing information about this syndrome that is relatively immune to experimental influence. In this article, we considered the relationship between possible movement disturbance and symptoms of autism and introduced an experimental model that may be useful for rehabilitation and diagnostic purposes: the reach-to-grasp movement. Research is reviewed that characterizes kinematically the reach-to-grasp movement in children with autism compared with age-matched 'controls'. Unlike the age-matched children, autistic children showed differences in movement planning and execution, supporting the view that movement disturbances may play a part in the phenomenon of autism.
doi:10.1098/rstb.2002.1205
PMCID: PMC1693116  PMID: 12639336

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