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Genetic factors are important
- recurrence rates are high
- Family risk: 5% of siblings are affected
- Twin studies: heritability of 60-90%
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BARTLETT et al 2012
have yet to fully understand genetics behind ASD
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ARKING et al 2008
CNTNAP2 observed in those diagnosed with ASD and their relatives
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Relatives
20-30% of relatives are likely to have social and cognitive abnormalities but do not meet criteria of ASD (e.g. may have intense interests but not ASD)
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NAVA 2013
copy number variations on chromosomes 15, 16 and 17 implicated in ASD
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NEWSCHAFFER 2006
- proposed a variety of factors involved in ASD such as infection and immune dysfunction, metals and neuropeptides. However other studies have yet to find links.
- Also implicated is the MMR vaccine which has since been shown to be unsupported by evidence
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Neurobiology of ASD
- Enlarged head circumference: normal at birth but gets 10% larger at 3/4 years could be due to poor synaptic pruning
- Increased cell size and cell packaging density
- Poor neural connectivity associated with white matter anomalies
- Very few cross disorder comparisons so cannot conclude if these are ASD specific
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AMARAL et al 2008
- IFG (social impairment and communication)
- Superior temporal sulcus (communication)
- Orbitofrontal cortex (repetitive behaviours)
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ASD behaviour
- significant and persistent deficits in social communication and interactions
- restricted, repetitive patterns of behaviour, interests and activities
- Symptoms must be present in early childhood
- Life-long disorder
- IQ strong predictor of outcome
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KANNER 1947
reported repetitive behaviours, insistence to stick to routine, don’t under jokes (take them literally)
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BAIRD et al 2006
1% of UK population
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