International Meeting for Autism Research (London, May 15-17, 2008): Craniofacial Dysmorphology in Autism: Embryologically-derived Measures

Craniofacial Dysmorphology in Autism: Embryologically-derived Measures

Friday, May 16, 2008
Champagne Terrace/Bordeaux (Novotel London West)
11:30 AM
C. Deutsch , Psychobiology Program, Shriver Center, Shriver Center and McLean Hospital, Harvard Medical School, Waltham, MA
A. Hunt , Shriver Center, Waltham, MA
L. Farkas , Hospital for Sick Children, Toronto, ON, Canada
Background: Several laboratories, including ours, have reported excessive craniofacial dysmorphology in autistic disorders. The presence of dysmorphology in a brain-based disorder is plausible, given the closely linked embryologic heritage of craniofacial and brain morphogenesis. Here, we adopt reliable quantitative methods to measure dysmorphology and apply embryologic principles to render these phenotypes biologically interpretable.
Objectives: We have applied these methods to the study of subjects with autism who have limited verbal abilities, comparing them to a group of typically-developing subjects.
Methods: We applied the Deutsch and Farkas dysmorphology protocol from the North American atlas Anthropometry of the Head and Face, measuring 11 subjects with autism and 22 matched typically-developing subjects. Individuals with known craniofacial syndromes were excluded from this analysis. Quantitative craniofacial measurements were conditioned on age, gender, and ethnicity, using the atlas’ extensive normative database. Our approach is to examine combinations of anomalies chosen to reflect developmental factors. Here, we report on two embryologically derived classes: mechanism of alteration (malformations, primary errors of morphogenesis; and deformations, caused by mechanical constraint), and Anlagen derivatives (embryologic primordia forming the face and head: frontonasal, maxillary, and mandibular).
Results: Malformations were excessive in autism relative to the typically-developing group (p < .05); in contrast, deformations were not overrepresented (n.s.). There was also a marked excess of frontonasal anomaly scores (p < .02) in the autism group, but not of maxillary and mandibular anomaly scores (n.s.).

Conclusions: Using these objective, reliable measures, we determined that there was excessive dysmorphology in an autistic sample characterized by limited verbal abilities. There was a preponderance of malformations, as well as anomalies arising from frontonasal prominence derivatives. These findings may find application in studies of the pathogenesis of autism, potentially revealing more homogeneous subgroups with respect to etiology.