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Important notice

doctorportal Learning is on the move as we will be launching a new website very shortly. If you would like to sign up to dp Learning now to register for CPD learning or to use our CPD tracker, please email support@doctorportal.com.au so we can assist you. If you are already signed up to doctorportal Learning, your login will work in the new site so you can continue to enrol for learning, complete an online module, or access your CPD tracker report.

To access and/or sign up for other resources such as Jobs Board, Bookshop or InSight+, please go to www.mja.com.au, or click the relevant menu item and you will be redirected.

All other doctorportal services, such as Find A Doctor, are no longer available.

Is autism one or multiple disorders?

From the earliest description of autism in 1943 to the present day, there has been a widely held view that the behavioural anomalies associated with the disorder occur more often together than would be expected by chance, and therefore there will be a single causal pathway that explains the non-random co-occurrence of these symptoms.1 The phenotypic variability of autism has proved to be a major stumbling block for aetiological research. The heterogeneity spans the entire range of intelligence quotients (IQs) and language abilities, as well as other behavioural, communicative and social functions. While any psychiatric condition is likely to incorporate a degree of heterogeneity, the variability in the nature and severity of behaviours observed in autism is thought to exceed that of other disorders.1,2 The variety of presentations of people with autism is described in the Box.

Major advances in aetiological research have been made over this period; most notably, the discovery from twin studies of greater concordance for autism among monozygotic (70%–90%) compared with dizygotic (0–10%) twin pairs, providing clear evidence that the disorder is, at least in part, genetic in origin.3 However, after seven decades of intense investigation, the research community is yet…