Heritability of abnormalities in limbic networks of autism spectrum disorder children: Evidence from an autism spectrum disorder twin study.
Limbic white-matter cables are weaker in young autism twins and genes play a big role.
01Research in Context
What this study did
Fu et al. (2022) scanned both twins in many pairs. Some pairs had autism, some did not.
They used brain scans that track water movement. This shows the health of white-matter cables in limbic areas.
What they found
Twins with autism had weaker limbic cables than twins without autism.
Genes explained a large share of these cable differences. The cables matter for emotion and social cues.
How this fits with other research
Palka Bayard de Volo et al. (2021) also looked at heritability, but in adults. They found autism trait scores are highly heritable too. Together, the papers show genes shape autism both in brain wires and in daily traits.
McGrath et al. (2013) used the same scan type in adults. They saw white-matter problems in a different cable linked to vision. The new study adds that limbic cables are weak even in very young children.
Thompson et al. (1986) studied autism twins decades ago. They found serotonin uptake, not cables, was genetically set. The old and new findings fit: genes can sway both brain chemistry and brain wiring.
Why it matters
You now have clear evidence that limbic cable integrity is partly genetic and already present in toddlers. When you see social or emotional delays, remember the brain basis is real and runs in families. Share this with parents to reduce blame and plan early, targeted social skills work.
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02At a glance
03Original abstract
Although the limbic system is closely related to emotion and social behaviors, little is known about the integrity of limbic pathways and how genetics influence the anatomical abnormalities of limbic networks in children with autism spectrum disorder (ASD). Therefore, we used an ASD twin study design to evaluate the microstructural integrity and autism-related differences in limbic pathways of young children with ASD and to estimate the heritability of limbic tracts microstructure variance. We obtained diffusion tensor imaging scans from 33 pairs of twins with ASD aged 2-9 years and 20 age-matched typically developing children. The ACE model was used to estimate the relative effects of additive genetic factors (A), shared environmental factors (C) and specific environmental factors (E) on the variability of diffusivity measurements. We found a significant decrease in fractional anisotropy (FA) in the bilateral fornix and uncinate fasciculus (UF), as well as increased mean diffusivity (MD) and radial diffusivity (RD) in the bilateral fornix and right UF of ASD children. Correlation analysis showed that FA, MD, and lateralization indices of UF were correlated with autism diagnostic observation schedule scores. The ACE model revealed that genetic effects may drive some of the variability of microstructure in the bilateral fornix, cingulum, and left UF. In conclusion, in children with ASD, there are abnormalities in the white matter microstructure of the limbic system, which is related to the core symptoms; these abnormalities may be related to the relative contribution of genetic and environmental effects on specific tracts. LAY SUMMARY: Autism spectrum disorder (ASD) children have abnormal white matter structure in limbic system related to ASD symptoms, and genetic factors play an important role in the development of limbic tracts.
Autism research : official journal of the International Society for Autism Research, 2022 · doi:10.1002/aur.2686