Advancing Clinical Practice Through Recognition of Autism Subtypes

Date: 
March 19, 2008

To the well-informed autism community, the remarkably different ways in which autism may affect one individual from the next is perhaps noting the obvious . Beyond the core domains of autism, parents know all too well that their child may have a host of accompanying gastrointestinal problems as one of their major issues, while others may report sleep difficulties as a significant factor – and the list certainly doesn't end there. Increased awareness and study of this phenomenon may one day point to a multiplicity of underlying causes or potentially just different presentations of a handful of the same causes. One thing for certain is that this heterogeneity presents a real challenge for clinicians in the field in terms of diagnostic and treatment concerns. Comprehending and describing various subgroups of autism might be a way to advance the field of autism research and inch us closer toward efficiently prescribed treatment strategies.

As basic research advances our knowledge of autism, this needs to be translated into clinical practices. Two recent articles underscore the heterogeneity of autism and the importance of recognizing different types of autism in terms of how the individuals receive treatment as well as vigilance for concurrent issues which may arise. The first, "Autism Spectrum Disorders: Concurrent Clinical Disorders," examines potential clusters of co-morbid clinical conditions. The second, "Genetics Evaluation for the Etiologic Diagnosis of Autism Spectrum Disorders," outlines the diverse genetic factors which play into different autism spectrum disorders, as well as prescribes a template for evaluating potential genetic etiologies. Both point to the need for future prospective studies designed to better understand the phenomenon.

Published in the Journal of Child Neurology, the first of these articles examines a wide variety of concurrent medical and psychiatric conditions in a group of children with autism spectrum disorders. Amongst these are gastrointestinal disorders, food intolerance, immune dysregulation, sleep disorders, seizures, depression, and aggressive/self-injurious behaviors. More than half of the participating children exhibited sleep disorders and food intolerance at some point in their lives.

Many of these children had more than one co-occurring condition - gastrointestinal issues in addition to sleep dysfunction, for example. The study investigates the possibility of existing common pathophysiologic causes which result in "subgroups" of autism spectrum disorders which share clusters of symptoms. Indeed, an association was found between sleep disorders, gastrointestinal dysfunction, and mood disorder. Similarly, an association between food intolerance and gastrointestinal dysfunction was found. The existence of a mood disorder was found to be associated with the development of aggressive or self-injurious behaviors. These associations suggest that one concurrent condition may be responsible for the other, or that they potentially stem from the same root cause. Recognition of these clusters of conditions may advance a specific therapeutic strategy, as treatment aimed at a primary cause of multiple conditions would be more effective than applying symptomatic control to those that crop up.

With the incidence of autism spectrum disorders increasing over the last 10 years, referrals to clinical geneticists to find an underlying cause is also experiencing a tremendous upswing. The second article, published in the journal Genetics in Medicine, prescribes a template for a tiered evaluation approach for these clinicians to utilize when evaluating an individual with autism. Due to the recent explosion of genetic findings in autism, there are now many known genetic factors which lead to autism-like syndromes. With this in mind, and with the ever growing knowledge of genetic evaluation techniques, the authors are assisting the clinical community by proposing a consistent approach to clinical examination to increase the yield of etiologic genetic testing.

It is estimated that currently, of those who undergo thorough evaluation, only 15% have an underlying cause identified. As this testing becomes more and more commonplace, the tiered approach outlined in this paper, which would evaluate known genetic conditions as well as various metabolic and brain structural factors, might increase this yield to around 40%. The cost and time required (in excess of six months, in some cases) to complete an exhaustive evaluation are factors to consider. However, accurately pinpointing a cause would help to alleviate parental anxiety, shine light on any associated medical conditions and/or environmental interplay, as well as provide a starting point for family and care providers in applying appropriately tailored treatment.

Together, these studies highlight the importance of considering heterogeneity for biologic research but also for diagnosis and treatment and the value of a multidisciplinary approach. Autism Speaks has developed initiatives and programs promoting and supporting research in these areas. The Autism Treatment Network, a collaboration of 15 medical centers, is focusing on ways to improve comprehensive care for children with autism by developing consensus standards for medical care. The network has developed a patient registry and ATN subspecialty "think tanks" to address co-morbid conditions and how they affect behaviors. Autism Speaks provides the resources to facilitate genetic research through its Autism Genetic Resource Exchange. Autism Speaks has also recently launched a Diagnostic Initiative that will use multidisciplinary approaches to diagnostic research.

Learn more about the Autism Treatment Network (ATN)
Learn more about the Autism Genetic Resource Exchange (AGRE)
Learn more about Autism Speaks' Diagnostic Initiatives


Ming X, Brimacombe JC, Zimmerman-Bier B, Wagner GC. Autism Spectrum Disorders: Concurrent Clinical Disorders. J Child Neurol. 2008; 23;6.

Schaefer GB, Mendelson NJ. Genetics Evaluation for the Etiologic Diagnosis of Autism Spectrum Disorders. Genet Med. 2008; 10(1):4-12.