Facial asymmetry in parents of children on the autism spectrum.
Facial asymmetry, a subtle physical trait, runs in families of autistic children and may serve as a low-cost biological marker of genetic liability.
01Research in Context
What this study did
Tan et al. (2021) measured facial asymmetry in parents of autistic children. They compared these parents to adults who had no family history of autism.
The team used 3-D photos to spot tiny left-right differences in face shape. These differences are too small to notice with the naked eye.
What they found
Parents of autistic kids had slightly more facial asymmetry than the control group. The difference was real but small.
This hints that uneven facial growth runs in families and may mark shared genes.
How this fits with other research
Boutrus et al. (2019) first saw the same asymmetry in autistic children themselves. Weiting extends that work by showing the trait also lives in parents, strengthening the heredity story.
Wallace et al. (2010) found that parents struggle with reading faces. Together the two papers sketch a broader face phenotype: parents show both subtle shape and subtle skill differences.
Ozgen et al. (2011) and Angkustsiri et al. (2011) counted dozens of minor physical anomalies in autistic kids. Weiting narrows the lens to one easy-to-measure marker in parents, making future screens simpler.
Why it matters
You now have a quick, low-cost clue about genetic liability: a 3-D photo. If you work with families who already have one autistic child, snapping a photo of mom or dad could flag broader autism phenotype status without long interviews. Pair this with parent-report tools to sharpen your family risk profile and guide early monitoring of younger siblings.
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02At a glance
03Original abstract
Greater facial asymmetry has been consistently found in children with autism spectrum disorder (ASD) relative to children without ASD. There is substantial evidence that both facial structure and the recurrence of ASD diagnosis are highly heritable within a nuclear family. Furthermore, sub-clinical levels of autistic-like behavioural characteristics have also been reported in first-degree relatives of individuals with ASD, commonly known as the 'broad autism phenotype'. Therefore, the aim of the current study was to examine whether a broad autism phenotype expresses as facial asymmetry among 192 biological parents of autistic individuals (134 mothers) compared to those of 163 age-matched adults without a family history of ASD (113 females). Using dense surface-modelling techniques on three dimensional facial images, we found evidence for greater facial asymmetry in parents of autistic individuals compared to age-matched adults in the comparison group (p = 0.046, d = 0.21 [0.002, 0.42]). Considering previous findings and the current results, we conclude that facial asymmetry expressed in the facial morphology of autistic children may be related to heritability factors. LAY ABSTRACT: In a previous study, we showed that autistic children presented with greater facial asymmetry than non-autistic children. In the current study, we examined the amount of facial asymmetry shown on three-dimensional facial images of 192 parents of autistic children compared to a control group consisting of 163 similarly aged adults with no known history of autism. Although parents did show greater levels of facial asymmetry than those in the control group, this effect is statistically small. We concluded that the facial asymmetry previously found in autistic children may be related to genetic factors.
Autism research : official journal of the International Society for Autism Research, 2021 · doi:10.1002/aur.2612