1. Cottrell CE, Bir N, Varga E, Alvarez CE, Bouyain S, Zernzach R, Thrush DL, Evans J, Trimarchi M, Butter EM, Cunningham D, Gastier-Foster JM, McBride KL, Herman GE. Contactin 4 as an autism susceptibility locus. Autism Res;2011 (Feb 9)
Structural and sequence variation have been described in several members of the contactin (CNTN) and contactin-associated protein (CNTNAP) gene families in association with neurodevelopmental disorders, including autism. Using array comparative genome hybridization (CGH), we identified a maternally inherited approximately 535 kb deletion at 3p26.3 encompassing the 5′ end of the contactin 4 gene (CNTN4) in a patient with autism. Based on this finding and previous reports implicating genomic rearrangements of CNTN4 in autism spectrum disorders (ASDs) and 3p(-) microdeletion syndrome, we undertook sequencing of the coding regions of the gene in a local ASD cohort in comparison with a set of controls. Unique missense variants were identified in 4 of 75 unrelated individuals with ASD, as well as in 1 of 107 controls. All of the amino acid substitutions were nonsynonomous, occurred at evolutionarily conserved positions, and were, thus, felt likely to be deleterious. However, these data did not reach statistical significance, nor did the variants segregate with disease within all of the ASD families. Finally, there was no detectable difference in binding of two of the variants to the interacting protein PTPRG in vitro. Thus, additional larger studies will be necessary to determine whether CNTN4 functions as an autism susceptibility locus in combination with other genetic and/or environmental factors.
2. Jaarsma P, Welin S. Autism as a Natural Human Variation: Reflections on the Claims of the Neurodiversity Movement. Health Care Anal;2011 (Feb 11)
Neurodiversity has remained a controversial concept over the last decade. In its broadest sense the concept of neurodiversity regards atypical neurological development as a normal human difference. The neurodiversity claim contains at least two different aspects. The first aspect is that autism, among other neurological conditions, is first and foremost a natural variation. The other aspect is about conferring rights and in particular value to the neurodiversity condition, demanding recognition and acceptance. Autism can be seen as a natural variation on par with for example homosexuality. The broad version of the neurodiversity claim, covering low-functioning as well as high-functioning autism, is problematic. Only a narrow conception of neurodiversity, referring exclusively to high-functioning autists, is reasonable. We will discuss the effects of DSM categorization and the medical model for high functioning autists. After a discussion of autism as a culture we will analyze various possible strategies for the neurodiversity movement to claim extra resources for autists as members of an underprivileged culture without being labelled disabled or as having a disorder. We will discuss their vulnerable status as a group and what obligation that confers on the majority of neurotypicals.
3. Parner ET, Thorsen P, Dixon G, de Klerk N, Leonard H, Nassar N, Bourke J, Bower C, Glasson EJ. A Comparison of Autism Prevalence Trends in Denmark and Western Australia. J Autism Dev Disord;2011 (Feb 11)
Prevalence statistics for autism spectrum disorders (ASD) vary widely across geographical boundaries. Some variation can be explained by diagnostic methods, case ascertainment and age at diagnosis. This study compared prevalence statistics for two distinct geographical regions, Denmark and Western Australia, both of which have had population-based registers and consistent classification systems operating over the past decade. Overall ASD prevalence rates were higher in Denmark (68.5 per 10,000 children) compared with Western Australia (51.0 per 10,000 children), while the diagnosis of childhood autism was more prevalent in Western Australia (39.3 per 10,000 children) compared with Denmark (21.8 per 10,000 children). These differences are probably caused by local phenomena affecting case ascertainment but influence from biological or geographical factors may exist.
4. Sala M, Braida D, Lentini D, Busnelli M, Bulgheroni E, Capurro V, Finardi A, Donzelli A, Pattini L, Rubino T, Parolaro D, Nishimori K, Parenti M, Chini B. Pharmacologic Rescue of Impaired Cognitive Flexibility, Social Deficits, Increased Aggression, and Seizure Susceptibility in Oxytocin Receptor Null Mice: A Neurobehavioral Model of Autism. Biol Psychiatry;2011 (Feb 7)
BACKGROUND: Oxytocin (OT) has been suggested as a treatment to improve social behavior in autistic patients. Accordingly, the OT (Oxt(-/-)) and the OT receptor null mice (Oxtr(-/-)) display autistic-like deficits in social behavior, increased aggression, and reduced ultrasonic vocalization. METHODS: Oxtr(-/-) mice were characterized for general health, sociability, social novelty, cognitive flexibility, aggression, and seizure susceptibility. Because vasopressin (AVP) and OT cooperate in controlling social behavior, learning, and aggression, they were tested for possible rescue of the impaired behaviors. Primary hyppocampal cultures from Oxtr(+/+) and Oxtr(-/-) mouse embryos were established to investigate the balance between gamma-aminobutyric acid (GABA) and glutamate synapses and the expression levels of OT and AVP (V1a) receptors were determined by autoradiography. RESULTS: Oxtr(-/-) mice display two additional, highly relevant, phenotypic characteristics: 1) a resistance to change in a learned pattern of behavior, comparable to restricted interests and repetitive behavior in autism, and 2) an increased susceptibility to seizures, a frequent and clinically relevant symptom of autism. We also show that intracerebral administration of both OT and AVP lowers aggression and fully reverts social and learning defects by acting on V1a receptors and that seizure susceptibility is antagonized by peripherally administered OT. Finally, we detect a decreased ratio of GABA-ergic versus total presynapses in hippocampal neurons of Oxtr(-/-) mice. CONCLUSIONS: Autistic-like symptoms are rescued on administration of AVP and OT to young Oxtr(-/-) adult animals. The Oxtr(-/-) mouse is thus instrumental to investigate the neurochemical and synaptic abnormalities underlying autistic-like disturbances and to test new strategies of pharmacologic intervention.
5. Schoen E, Paul R, Chawarska K. Phonology and vocal behavior in toddlers with autism spectrum disorders. Autism Res;2011 (Feb 9)
The purpose of this study is to examine the phonological and other vocal productions of children, 18-36 months, with autism spectrum disorder (ASD) and to compare these productions to those of age-matched and language-matched controls. Speech samples were obtained from 30 toddlers with ASD, 11 age-matched toddlers and 23 language-matched toddlers during either parent-child or clinician-child play sessions. Samples were coded for a variety of speech-like and nonspeech vocalization productions. Toddlers with ASD produced speech-like vocalizations similar to those of language-matched peers, but produced significantly more atypical nonspeech vocalizations when compared to both control groups. Toddlers with ASD show speech-like sound production that is linked to their language level, in a manner similar to that seen in typical development. The main area of difference in vocal development in this population is in the production of atypical vocalizations. Findings suggest that toddlers with ASDs do not tune into the language model of their environment. Failure to attend to the ambient language environment negatively impacts the ability to acquire spoken language.
6. Vanderbruggen N, Van Geit N, Bissay V, Zeeuws D, Santermans L, Baeken C. Asperger syndrome, violent thoughts and clinically isolated syndrome. Acta Neurol Belg;2010 (Dec);110(4):334-336.
A young man, 23 years old, with a clinically isolated syndrome (CIS), presented violent thoughts during a neurological consultation. He was diagnosed with Asperger Syndrome based on a psychiatric and (neuro)psychological examination. Possible risk factors for acting-out and the implications for treatment, if CIS would evolve to MS, are discussed based on a review of the literature.
7. Zhang X, Su J, Cui N, Gai H, Wu Z, Jiang C. The disruption of central CO2 chemosensitivity in a mouse model of Rett syndrome. Am J Physiol Cell Physiol;2011 (Feb 9)
People with Rett syndrome (RTT) have breathing instability in addition to other neuropathological manifestations. The breathing disturbances contribute to the high incidence of unexplained death and abnormal brain development. However, the cellular mechanisms underlying the breathing abnormalities remain unclear. To test the hypothesis that the central CO(2) chemoreception in these people is disrupted, we studied the CO(2) chemosensitivity in a mouse model of RTT. The Mecp2-null mice showed a selective loss of their respiratory response to 1-3% CO(2) (mild hypercapnia), while they displayed more regular breathing and normal response to 6-9% CO(2) (severe hypercapnia). The defect was alleviated with the NE uptake blocker desipramine (10mg/kg/day, i.p., for 5-7 days). Consistent with the in vivo observations, in vitro studies in brain slices indicated that CO(2) chemosensitivity of locus coeruleus (LC) neurons was impaired in Mecp2-null mice. Two major neuronal pH-sensitive Kir currents that resembled homomeric Kir4.1 and heteromeric Ki4.1/Kir5.1 channels were identified in the LC neurons. The screening of Kir channels with real-time PCR indicated the overexpression of Kir4.1 in the LC region of Mecp2-null mice. In a heterologous expression system, an overexpression of Kir4.1 resulted in a reduction in the pH sensitivity of the heteromeric Kir4.1-Kir5.1 channels. Given that Kir4.1 and Kir5.1 subunits are also expressed in brainstem respiration-related areas, the Kir4.1 overexpression may not allow CO(2) to be detected until hypercapnia becomes severe, leading to periodical hyper- and hypoventilation in Mecp2-null mice and, perhaps, in people with RTT as well.
