Facial phenotypes in subgroups of prepubertal boys with ASDs are correlated with clinical phenotypes

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Facial phenotypes in subgroups of prepubertal boys with autism spectrum

disorders are correlated with clinical phenotypes.

<http://www.ncbi.nlm.nih.gov/pubmed/21999758>

Aldridge K, ID, Cole KK, Austin JR, Takahashi TN, Duan Y, Miles JH.

Mol Autism. 2011 Oct 14;2(1):15.

BACKGROUND: The brain develops in concert and in coordination with the

developing facial tissues, with each influencing the development of the

other and sharing genetic signaling pathways. Autism spectrum disorders

(ASDs) result from alterations in the embryological brain, suggesting

that the development of the faces of children with ASD may result in

subtle facial differences compared to typically developing children. In

this study, we tested two hypotheses. First, we asked whether children

with ASD display a subtle but distinct facial phenotype compared to

typically developing children. Second, we sought to determine whether

there are subgroups of facial phenotypes within the population of

children with ASD that denote biologically discrete subgroups.

METHODS: The 3dMD cranial System was used to acquire three-dimensional

stereophotogrammetric images for our study sample of 8- to 12-year-old

boys diagnosed with essential ASD (n = 65) and typically developing boys

(n = 41) following approved Institutional Review Board protocols.

Three-dimensional coordinates were recorded for 17 facial anthropometric

landmarks using the 3dMD Patient software. Statistical comparisons of

facial phenotypes were completed using Euclidean Distance Matrix

Analysis and Principal Coordinates Analysis. Data representing clinical

and behavioral traits were statistically compared among groups by using

χ2 tests, Fisher's exact tests, Kolmogorov-Smirnov tests and Student's

t-tests where appropriate.

RESULTS: */First, we found that there are significant differences in

facial morphology in boys with ASD compared to typically developing

boys. Second, we also found two subgroups of boys with ASD with facial

morphology that differed from the majority of the boys with ASD and the

typically developing boys. Furthermore, membership in each of these

distinct subgroups was correlated with particular clinical and

behavioral traits/*.

CONCLUSIONS: */Boys with ASD display a facial phenotype distinct from

that of typically developing boys, which may reflect alterations in the

prenatal development of the brain. Subgroups of boys with ASD defined by

distinct facial morphologies correlated with clinical and behavioral

traits, suggesting potentially different etiologies and genetic

differences compared to the larger group of boys with ASD/*. Further

investigations into genes involved in neurodevelopment and craniofacial

development of these subgroups will help to elucidate the causes and

significance of these subtle facial differences.

[sic: The authors last sentence omits environmental factors that can

alter neurodevelopment and craniofacial development. Oh well...]