Autism is a neurodevelopmental disorder characterized by impairments in social interactions, communication, and behavior. Multiple lines of evidence support the notion that most cases of autism likely have an underlying genetic cause or predisposition. Like mental retardation, autism is likely to be caused by many different genetic mechanisms and genes rather than a single, or few, major genes or environmental effects. In this review, we will focus on the cytogenetic contribution to uncovering regions of the genome involved in autism. Some common cytogenetic imbalances already known to cause autism will be highlighted. Routine genetic testing in clinical (CLIA-certified) diagnostic laboratories can identify the specific etiology and recurrence risk in 10% to 15% of autism cases and is clinically indicated for any child with autism. Powerful new methods for identifying novel regions of the genome causing or contributing to autism also will be discussed and will start to explain the etiology for some percentage of the remaining 85% to 90% of autism cases.
"The region overlaps with the Prader–Willi and Angelman imprinted gene locus, with deletions of the maternally inherited 15q11-q13 interval, paternal uniparental disomy for chromosome 15 and specific mutation of the UBE3A gene resulting in Angelman syndrome whereas deletions of the paternally inherited 15q11-q13 interval and maternal uniparental disomy of chromosome 15 lead to a distinct condition, namely Prader–Willi syndrome (Jiang et al., 1998). In addition to these specific disorders, large maternally derived duplications of this interval were one of the earliest (Cook et al., 1997) and are still one of the most consistent cytogenetic observations for ASD, accounting for almost 3% of cases (Martin & Ledbetter, 2007). More recently, techniques developed to enable the detection of sub-microscopic chromosomal abnormalities have underlined the importance of CNV duplications spanning the 15q11-q13 interval in the aetiology of ASD (Christian et al., 2008; Glessner et al., 2009). "
[Show abstract][Hide abstract] ABSTRACT: Rodent models are a key factor in the process of translating psychiatric genetics and genomics findings, allowing us to shed light on how risk-genes confer changes in neurobiology by merging different types of data across fields, from behavioural neuroscience to the burgeoning omics (e.g. genomics, epigenomics, proteomics, etc.). Moreover, they also provide an indispensable first step for drug discovery. However, recent evidence from both clinical and genetic studies highlights possible limitations in the current methods for classifying psychiatric illness, as both symptomology and underlying genetic risk are found to increasingly overlap across disorder diagnoses. Meanwhile, integration of data from animal models across disorders is currently limited. Here, we argue that behavioural neuroscience is in danger of missing informative data because of the practice of trying to ‘diagnose’ an animal model with a psychiatric illness. What is needed is a shift in emphasis, from seeking to ally an animal model to a specific disorder, to one focused on a more systematic assessment of the neurobiological and behavioural outcomes of any given genetic or environmental manipulation.
European Journal of Neuroscience 05/2014; 39(11). DOI:10.1111/ejn.12607 · 3.18 Impact Factor
"This single microdeletion CNV represents the second most common chromosomal disruption associated with autism and duplication of this region (∼500 kb) has also been implicated in ASD  . Besides chromosome 16, the highest proportion of autism-linked maternal chromosomal abnormalities is found on 15q with other less frequent deletions or duplications on chromosomes 2q and 22q  . "
[Show abstract][Hide abstract] ABSTRACT: Autism spectrum disorders (ASDs) have become increasingly common in recent years. The discovery of single-nucleotide polymorphisms and accompanying copy number variations within the genome has increased our understanding of the architecture of the disease. These genetic and genomic alterations coupled with epigenetic phenomena have pointed to a neuroimmunopathological mechanism for ASD. Model animal studies, developmental biology, and affective neuroscience laid a foundation for dissecting the neural pathways impacted by these disease-generating mechanisms. The goal of current autism research is directed toward a systems biological approach to find the most basic genetic and environmental causes to this severe developmental disease. It is hoped that future genomic and neuroimmunological research will be directed toward finding the road toward prevention, treatment, and cure of ASD.
[Show abstract][Hide abstract] ABSTRACT: We argue that autism and psychosis spectrum disorders cannot be conceptualized as polar extremes of mentalizing ability. We raise two main objections: (1) the autistic-psychotic continuum, as conceptualized by the authors, excludes defining features of schizophrenia spectrum: negative symptoms, which correlate more strongly with mentalizing impairments; and (2) little evidence exists for a relationship between mentalizing ability and positive symptoms.
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