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PubMed2003

A genomewide screen of 345 families for autism-susceptibility loci.

We previously reported a genomewide scan to identify autism-susceptibility loci in 110 multiplex families, showing suggestive evidence (P <.01) for linkage to autism-spectrum disorders (ASD) on chromosomes 5, 8, 16, 19, and X and showing nominal evidence (P <.05) on several additional chromosomes (2, 3, 4, 10, 11, 12, 15, 18, and 20). In this follow-up analysis we have increased the sample size threefold, while holding the study design constant, so that we now report 345 multiplex families, each with at least two siblings affected with autism or ASD phenotype. Along with 235 new multiplex families, 73 new microsatellite markers were also added in 10 regions, thereby increasing the marker density at these strategic locations from 10 cM to approximately 2 cM and bringing the total number of markers to 408 over the entire genome. Multipoint maximum LOD scores (MLS) obtained from affected-sib-pair analysis of all 345 families yielded suggestive evidence for linkage on chromosomes 17, 5, 11, 4, and 8 (listed in order by MLS) (P <.01). The most significant findings were an MLS of 2.83 (P =.00029) on chromosome 17q, near the serotonin transporter (5-hydroxytryptamine transporter [5-HTT]), and an MLS of 2.54 (P =.00059) on 5p. The present follow-up genome scan, which used a consistent research design across studies and examined the largest ASD sample collection reported to date, gave either equivalent or marginally increased evidence for linkage at several chromosomal regions implicated in our previous scan but eliminated evidence for linkage at other regions.

Autistic Disorder↗

PubMed2006

Search for autism loci by combined analysis of Autism Genetic Resource Exchange and Finnish families.

OBJECTIVE: Several genome-wide screens have been performed in autism spectrum disorders resulting in the identification of numerous putative susceptibility loci. Analyses of pooled primary data should result in an increased sample size and the different study samples have a potential to strengthen the evidence for some earlier identified loci, reveal novel loci, and even to provide information of the general significance of the locus. The objective of this study was to search for potential susceptibility loci for autism, which are supported by two independent samples. METHODS: We performed a combined analysis of the primary genome scan data of the Autism Genetic Resource Exchange (AGRE) and Finnish autism samples to reveal susceptibility loci potentially shared by these study samples. RESULTS: In the initial combined data analysis, the best loci (p < 0.05) were observed at 1p12-q25, 3p24-26, 4q21-31, 5p15-q12, 6q14-21, 7q33-36, 8q22-24, 17p12-q21, and 19p13-q13. The combined analysis of Finnish and AGRE families showed the most promising shared locus on 3p24-26 with nonparametric logarithm of odds (NPL) score of 2.20 (p = 0.011). The combined data analysis did not provide increased linkage evidence for the earlier identified loci on 3q25-27 or 17p12-q21. However, the 17p12-q21 locus remained promising also in the combined sample (NPL(all) =2.38, p = 0.0076). INTERPRETATION: Our study of 314 autism families highlights the importance of further analyses on 3p24-26 locus involving comprehensive molecular genetic analyses of oxytocin receptor gene (OXTR), a positional and functional candidate gene for autism.

Animals↗

PubMed2005

Ataxia, autism, and the cerebellum: a clinical study of 32 individuals with congenital ataxia.

The suggested link between autism and cerebellar dysfunction formed the background for a Swedish clinical study in 2001. Thirty-two children (17 females, 15 males; mean age 12y, SD 3y 10mo; range 6 to 21y) with a clinical suspicion of non-progressive congenital ataxia were examined, and parents were interviewed about the presence of neuropsychiatric problems in the child. Twelve children had simple ataxia, eight had ataxic diplegia, and 12 had 'borderline' ataxia. All but one of the 32 children had a mild to moderate gross motor disability according to Gross Motor Function Classification System (15 were categorized as level I, 16 as level II, and one child as level IV). Neuroimaging and neuropsychological testing were achieved in most cases. There was a strong association between learning disability* and autism spectrum disorder (often combined with hyperactivity disorder) on the one hand, and both simple and borderline 'ataxia' on the other, but a weaker link between ataxic diplegia and neuropsychiatric disorders. A correlation between cerebellar macropathology on neuroimaging and neuropsychiatric disorders was not supported. Congenital ataxia might not be a clear-cut syndrome of cerebellar disease, but one of many signs of prenatal events or syndromes, leading to a complex neurodevelopmental disorder including autism and learning disability.

Adolescent↗

PubMedDate not supplied

The teratology of autism.

Autism spectrum disorders affect behaviors that emerge at ages when typically developing children become increasingly social and communicative, but many lines of evidence suggest that the underlying alterations in the brain occur long before the period when symptoms become obvious. Studies of the behavior of children in the first year of life demonstrate that symptoms are often detectable in the first 6 months. The environmental factors known to increase the risk of autism have critical periods of action during embryogenesis. Minor malformations that occur frequently in people with autism are known to arise in the same stages of development. Anomalies reported from histological studies of the brain are consistent with an early alteration of development. Congenital syndromes with high rates of autism include somatic that originate early in the first trimester. In addition, it is possible to duplicate a number of anatomic and behavioral features characteristic of human cases by exposing rat embryos to a teratogenic dose of valproic acid at the time of neural tube closure.

Animals↗

PubMed2004

Adaptive behavior in autism and Pervasive Developmental Disorder-Not Otherwise Specified: microanalysis of scores on the Vineland Adaptive Behavior Scales.

The purpose of this study is to provide a microanalysis of differences in adaptive functioning seen between well-matched groups of school-aged children with autism and those diagnosed as having Pervasive Developmental Disorder-Not Otherwise Specified, all of whom functioned in the mild to moderate range of intellectual impairment. Findings indicate that the major area of difference between children with autism and those with Pervasive Developmental Disorder-Not Otherwise Specified, was expressive communication; specifically, the use of elaborations in syntax and morphology and in pragmatic use of language to convey and to seek information in discourse. Linear discriminant function analysis revealed that scores on just three of these expressive communication item sets correctly identified subjects in the two diagnostic categories with 80% overall accuracy. Implications of these findings for both diagnosis and intervention with children with Autism Spectrum Disorders will be discussed.

Activities of Daily Living↗

PubMed2002

Follow-up of children with language delay and features of autism from preschool years to middle childhood.

Eighteen children (13 males, five females) who had severe developmental language delay/disorder and some features of autism (although insufficient in severity and combination to meet ICD-10 diagnostic criteria for childhood autism) at preschool age (Time 1; mean age 4 years 4 months) were followed up 4 years later (Time 2; mean age 8 years 7 months). At the initial assessment the diagnostic dilemma was how much the social communication impairments and behavioural problems were secondary to the language problem and how much they constituted a genuine case of a pervasive developmental disorder. It was anticipated that at follow-up some children would continue to show social impairments but that in others social impairments would have receded as language competence improved. Follow-up assessments included the Wechsler Intelligence Scale for Children, the Clinical Evaluation of Language Fundamentals, the Children's Communication Checklist, and the Social Communication Questionnaire. At follow-up, five children had continuing language disorder and were considered to fulfil diagnostic criteria for childhood autism, four children had continuing language disorder and met criteria for atypical autism, and nine met criteria for atypical autism but had somewhat recovered language skills. Thus, even in the subgroup of children whose language ability had improved the features of autism had not dissipated. Severity of social communication impairments and repetitive behaviours at Time 1, rated retrospectively from case notes, were associated with severity of autism symptoms and pragmatic competence at Time 2. The findings are discussed in relation to the unclear boundary between autism spectrum disorders and language delay/disorder.

Autistic Disorder↗

PubMed2003

Lack of a relation between human neonatal thyroxine and pediatric neurobehavioral disorders.

The growth and differentiation of the central nervous system are closely related to the presence of iodine and thyroid hormones. It has been hypothesized that neurobehavioral disabilities of childhood, such as attention deficit hyperactivity disorder (ADHD), learning disorders, and autism can be attributed to fetal thyroidal endocrine disruption in utero. To determine whether there is an association between neonatal thyroid status and a subsequent diagnosis of a neurobehavioral disability, neonatal thyroxine (T(4)) levels have been used as the indicator of the presence of intrauterine thyroidal dysfunction. Neonatal T(4) levels were obtained from the neonatal hypothyroidism screening program. All cases were diagnosed at medical school diagnostic clinics, the diagnostic categories being ADHD, autism spectrum disorder, behavioral disorder, cognitive disorder, developmental delay, emotional disorder, learning disability, and speech/language disorder. Conditional logistic regression analysis was performed for each clinical condition. Odds ratios for the conditions ranged from 0.92 to 1.13 with p values ranging between 0.19 and 0.84. No significant differences were detected between neonatal T(4) values of the cases and the controls for any of the neurobehavioral conditions. All neonatal T(4) values were within normal ranges. The data provide no evidence to suggest that intrauterine thyroid status as reflected by the neonatal T(4) values had an impact on the neurologic disorders diagnosed in childhood.

Case-Control Studies↗

PubMed2005

Time trends in child and adolescent mental disorders.

PURPOSE OF REVIEW: 1995 saw the publication of a major review of time trends in psychosocial disorders of youth across the second half of the twentieth century. It found evidence for substantial increases in rates of youth crime, alcohol and drug use, depression and suicide in most industrialized countries in the decades following the Second World War, slowing in some instances in the 1980s. Ten years on, we review findings on more recent trends in rates of these and other indicators of child and adolescent mental health. RECENT FINDINGS: Prevalence estimates for autism spectrum disorders have increased in recent decades, as has public and professional awareness of hyperactivity and attention deficits. Trends in adolescent conduct problems, and in alcohol and drug use, appear to reflect culture-specific influences. Rates of suicide among young males, and self-harm among females have risen in many countries in recent years; trends in emotional disorders are more varied, but there is little evidence for any rise in rates of anorexia nervosa. Although some contributors to these trends have been identified, much remains to be learned about the key risks involved. SUMMARY: Monitoring time trends in child and adolescent mental health is essential for service planning; knowledge of changing trends can also provide important pointers to potential risk factors. Current data sources allow relatively reliable tracking of trends in some areas, but remain severely limited in others. Further research is needed to understand the mechanisms underlying recently identified trends in child and adolescent mental health.

Journal Article↗

PubMedDate not supplied

Captured by details: sense-making, language and communication in autism.

UNLABELLED: The communication of people with autism spectrum disorder (ASD) is characterized by a qualitative impairment in verbal and non-verbal communication. In past decades a growing body of descriptive studies has appeared on language and communication problems in ASD. Reviews suggest that the development of formal and semantic aspects is relatively spared, whereas pragmatic skills are considered to be specifically impaired. This unique profile was interpreted mainly within the framework of the theory of mind hypothesis, which links the social-communicative problems of people with autism to an incapacity to attribute mental states to themselves and others. This approach has proven useful, but has also left many questions unanswered. In more recent publications, limited intentionality and symbol formation have been identified as core problems in ASD. Problems in symbol formation in particular might be better understood from the viewpoint of the central coherence hypothesis, which conceptualizes ASD as a weaker drive for the integration of information. Possible links between cognitive findings and communication evoke new perspectives with respect to the complex of communication problems in ASD. LEARNING OUTCOMES: The reader of this manuscript will be able to (1) describe the communication deficit in ASD; (2) discuss the central coherence account of ASD in relation to problems in sense-making; and (3) explain how these difficulties might lead to problems in communication in autism.

Autistic Disorder↗

PubMed2006

Autism following a history of newborn encephalopathy: more than a coincidence?

Between June 1993 and December 1996, 276 term newborn infants with encephalopathy and 564 randomly selected term controls were enrolled in a population-based study of moderate and severe term newborn encephalopathy (NE) in Western Australia. During comprehensive neurobehavioural and cognitive follow-up of all patients and controls at 3 years and again at 5 years of age we found an unexpected but strong association between NE and autism spectrum disorders (ASDs). A diagnosis of ASD by age 5 years was reached using criteria according of the Diagnostic Statistical Manual, 4th edition. Linking records to the Western Australian Disability Services Commission Register ensured that no child in the study with ASD was missed. By age 5 years, 37 (13.4%) infants with NE and one (0.2%) control had died. Among the 239 survivors of NE, 12 (5%) were diagnosed with an ASD. Of these, 10 (4.2%) met the full criteria for autism, one had pervasive developmental disorder-not otherwise specified, and one had Asperger syndrome. Among the 563 surviving controls, five (0.8%) were diagnosed with an ASD: three with autism, one with autism/possible Asperger syndrome, and one with Asperger syndrome. Compared with the controls, the children who had experienced NE were 5.9 times (95% confidence interval 2.0-16.9) more likely to have been diagnosed with an ASD.

Autistic Disorder↗

PubMed2005

Validation of the phenomenon of autistic regression using home videotapes.

CONTEXT: To date, there has been no objective validation of the phenomenon of autistic regression early in life. OBJECTIVE: To validate parental report of autistic regression using behavioral data coded from home videotapes of children with autism spectrum disorder (ASD) vs typical development taken at 12 and 24 months of age. DESIGN: Home videotapes of 56 children's first and second birthday parties were collected from parents of young children with ASD with and without a reported history of regression and typically developing children. Child behaviors were coded by raters blind to child diagnosis and regression history. A parent interview that elicited information about parents' recall of early symptoms from birth was also administered. SETTING: Participants were recruited from a multidisciplinary study of autism conducted at a major university. PARTICIPANTS: Fifteen children with ASD with a history of regression, 21 children with ASD with early-onset autism, and 20 typically developing children and their parents participated. MAIN OUTCOME MEASURES: Observations of children's communicative, social, affective, repetitive behaviors, and toy play coded from videotapes of the toddlers' first and second birthday parties. RESULTS: Analyses revealed that infants with ASD with regression show similar use of joint attention and more frequent use of words and babble compared with typical infants at 12 months of age. In contrast, infants with ASD with early onset of symptoms and no regression displayed fewer joint attention and communicative behaviors at 12 months of age. By 24 months of age, both groups of toddlers with ASD displayed fewer instances of word use, vocalizations, declarative pointing, social gaze, and orienting to name as compared with typically developing 24-month-olds. Parent interview data suggested that some children with regression displayed difficulties in regulatory behavior before the regression occurred. CONCLUSION: This study validates the existence of early autistic regression.

Age of Onset↗

PubMed1994

Psychiatric family history and neurological disease in autistic spectrum disorders.

The authors obtained neurological assessments and psychiatric family history data for 40 children with autistic spectrum disorders (autism, Asperger syndrome and pervasive developmental disorder). Neurological evaluation included EEG, MRI, karyotyping and positron emission tomography as indicated. Family history data were obtained from family members during long-term follow-up. 20 probands had positive neurological findings, 18 with negative family history. 14 had no neurological findings and positive family histories; they tended to have higher function. Six had neither, and two had both. The segregation of neurological findings and familial affective disorder was highly significant. These findings suggest that an important subgroup of autistic spectrum disorders may be related etiologically to familial major affective disorders, and may represent the early-life onset of a severe phenotype of major affective, particularly bipolar, disease.

Adolescent↗

PubMed2005

Characteristics of fetal anticonvulsant syndrome associated autistic disorder.

The aim of this study was to evaluate the clinical features and frequency of autistic disorder or Asperger syndrome (AS; according to Diagnostic and Statistical Manual of Mental Disorders, 4th edition [DSM-IV] criteria) in children exposed to anticonvulsant medication in utero. During a 20-year study period, 626 children were born in Aberdeen to mothers taking antiepileptic drugs (AEDs). The study examined long-term effects of prenatal exposure to AEDs in 260 children (122 males, 138 females). Of these, 26 (16 males) were reported by parents to have social or behavioural difficulties. Eleven children (6 males, 5 females) fulfilled the DSM-IV criteria for autistic disorder and one (female) fulfilled the DSM-IV criteria for AS. These children comprised 4.6% of the exposed children studied, and 1.9% of all exposed children born during the study period. Mean age of these children at diagnosis was 5 years 4 months (SD 2y 11mo) and 9 years 10 months (SD 3y 10mo) at the time of this study. Other children from the group of 26 had difficulties in areas of speech and language development and social communication but did not meet the criteria for an autism spectrum disorder (ASD). Sodium valproate was the drug most commonly associated with autistic disorder, five of 56 (8.9%) of the study children exposed to sodium valproate alone had either autistic disorder or AS. It was concluded that prenatal exposure to anticonvulsant medication is a risk factor for the development of an ASD. Fetal anticonvulsant syndrome associated autistic disorder is characterized by an even sex ratio, absence of regression or skill loss, and language delay in the absence of global delay.

Anticonvulsants↗

PubMed2006

Aripiprazole use in individuals with intellectual disability and psychotic or behavioural disorders: a case series.

People with intellectual disabilities may be at greater risk of developing movement disorders as a consequence of their underlying neurological damage, especially when they are treated with typical antipsychotic agents. Aripiprazole is a novel antipsychotic quinolone derivative that has been approved for the treatment of schizophrenia in adults. However, there are few reports on the use of aripiprazole in people with intellectual disabilities. Herein, we report on the use of aripiprazole in five individuals with intellectual disabilities and psychotic illness (four cases) or challenging behaviour (one case). Four of the five patients had an additional diagnosis of schizophrenia and one had autism spectrum disorder and challenging behaviour. Issues related to the usefulness of aripiprazole in the management of schizophrenia and challenging behaviour in people with intellectual disabilities are also discussed. Aripiprazole was well tolerated and effective in each of the cases and appears to be a safe and efficacious alternative in the management of patients with both intellectual disabilities and schizophrenia. It can also be a useful treatment option in the management of challenging behaviour, especially when it is used as a part of a biopsychosocial approach.

Adolescent↗

PubMed2003

A systems neuroscience approach to autism: biological, cognitive, and clinical perspectives.

Autism is a behaviorally defined disorder characterized by a broad constellation of symptoms. Numerous studies directed to the biological substrate demonstrate clear effects of neurodevelopmental differences that will likely point to the etiology, course, and long-term outcomes of the disorder. Consistently replicated research on the neural underpinnings of autism is reviewed. In general, results suggest several main conclusions: First, autism is a heterogeneous disorder and is likely to have multiple possible etiologies; second, structural brain studies have indicated a variety of diffuse anatomical differences, reflective of an early developmental change in the growth or pruning of neural tissue, rather than localized lesions; similarly, neurochemical studies suggest early, neuromodulatory discrepancies rather than gross or localized abnormalities; and finally, there are a number of limitations on studies of brain activity that to date preclude definitive answers to questions of how the brain functions differently in autism. The large number of active research programs investigating the cognitive neuroscience of autism spectrum disorders, in combination with the exciting development of new methodologies and tools in this area, indicates the drama and excitement of work in this area.

Autistic Disorder↗

PubMed2004

Abnormal global processing along the dorsal visual pathway in autism: a possible mechanism for weak visuospatial coherence?

Frith and Happe (Frith, U., & Happe, F. (1994). Autism: Beyond theory of mind. Cognition, 50, 115-132) argue that individuals with autism exhibit 'weak central coherence': an inability to integrate elements of information into coherent wholes. Some authors have speculated that a high-level impairment might be present in the dorsal visual pathway in autism, and furthermore, that this might account for weak central coherence, at least at the visuospatial level. We assessed the integrity of the dorsal visual pathway in children diagnosed with an autism spectrum disorder (ASD), and in typically developing children, using two visual tasks, one examining functioning at higher levels of the dorsal cortical stream (Global Dot Motion (GDM)), and the other assessing lower-level dorsal stream functioning (Flicker Contrast Sensitivity (FCS)). Central coherence was tested using the Children's Embedded Figures Test (CEFT). Relative to the typically developing children, the children with ASD had shorter CEFT latencies and higher GDM thresholds but equivalent FCS thresholds. Additionally, CEFT latencies were inversely related to GDM thresholds in the ASD group. These outcomes indicate that the elevated global motion thresholds in autism are the result of high-level impairments in dorsal cortical regions. Weak visuospatial coherence in autism may be in the form of abnormal cooperative mechanisms in extra-striate cortical areas, which might contribute to differential performance when processing stimuli as Gestalts, including both dynamic (i.e., global motion perception) and static (i.e., disembedding performance) stimuli.

Autistic Disorder↗

PubMed2006

Searching for ways out of the autism maze: genetic, epigenetic and environmental clues.

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/).

Animals↗

PubMed2024

Exome sequencing reveals neurodevelopmental genes in simplex consanguineous Iranian families with syndromic autism.

BACKGROUND AND OBJECTIVE: Autosomal recessive genetic disorders pose significant health challenges in regions where consanguineous marriages are prevalent. The utilization of exome sequencing as a frequently employed methodology has enabled a clear delineation of diagnostic efficacy and mode of inheritance within multiplex consanguineous families. However, these aspects remain less elucidated within simplex families. METHODS: In this study involving 12 unrelated simplex Iranian families presenting syndromic autism, we conducted singleton exome sequencing. The identified genetic variants were validated using Sanger sequencing, and for the missense variants in FOXG1 and DMD, 3D protein structure modeling was carried out to substantiate their pathogenicity. To examine the expression patterns of the candidate genes in the fetal brain, adult brain, and muscle, RT-qPCR was employed. RESULTS: In four families, we detected an autosomal dominant gene (FOXG1), an autosomal recessive gene (CHKB), and two X-linked autism genes (IQSEC2 and DMD), indicating diverse inheritance patterns. In the remaining eight families, we were unable to identify any disease-associated genes. As a result, our variant detection rate stood at 33.3% (4/12), surpassing rates reported in similar studies of smaller cohorts. Among the four newly identified coding variants, three are de novo (heterozygous variant p.Trp546Ter in IQSEC2, heterozygous variant p.Ala188Glu in FOXG1, and hemizygous variant p.Leu211Met in DMD), while the homozygous variant p.Glu128Ter in CHKB was inherited from both healthy heterozygous parents. 3D protein structure modeling was carried out for the missense variants in FOXG1 and DMD, which predicted steric hindrance and spatial inhibition, respectively, supporting the pathogenicity of these human mutants. Additionally, the nonsense variant in CHKB is anticipated to influence its dimerization - crucial for choline kinase function - and the nonsense variant in IQSEC2 is predicted to eliminate three functional domains. Consequently, these distinct variants found in four unrelated individuals with autism are likely indicative of loss-of-function mutations. CONCLUSIONS: In our two syndromic autism families, we discovered variants in two muscular dystrophy genes, DMD and CHKB. Given that DMD and CHKB are recognized for their participation in the non-cognitive manifestations of muscular dystrophy, it indicates that some genes transcend the boundary of apparently unrelated clinical categories, thereby establishing a novel connection between ASD and muscular dystrophy. Our findings also shed light on the complex inheritance patterns observed in Iranian consanguineous simplex families and emphasize the connection between autism spectrum disorder and muscular dystrophy. This underscores a likely genetic convergence between neurodevelopmental and neuromuscular disorders.

Humans↗