Maternal serotonin transporter genotype affects risk for ASD with exposure to prenatal stress.
Moms with the stress-sensitive short 5-HTTLPR gene who endure high prenatal stress raise their child’s autism risk—early support for these women may prevent cases.
01Research in Context
What this study did
The team asked moms of kids with autism about stress they felt while pregnant.
They also checked each mom’s genes for the short form of the 5-HTTLPR transporter.
The short form makes a person react more strongly to stress hormones.
Researchers wanted to see if moms with both high stress and the short gene had more children with ASD.
What they found
Mothers who carried the short allele and reported lots of prenatal stress were more likely to have a child with autism.
The same stress level in moms with the long gene did not raise risk as much.
Timing mattered: stress in early and mid-pregnancy showed the strongest link.
How this fits with other research
Pritchard et al. (1987) first tied serotonin to autism by measuring the chemical in children’s blood. Eussen et al. (2016) moves that idea backward in time, showing the mother’s serotonin-related gene shapes risk before birth.
Chu et al. (2009) and Ljubičić et al. (2025) show that raising a child with autism stresses parents now. The target paper flips the arrow: maternal stress during pregnancy may help cause the child’s autism in the first place.
Ahlborn et al. (2008) found high platelet serotonin in some kids with PDD but saw no gut leakiness. The new study does not clash; it simply points to a different serotonin pathway—mom’s gene—rather than the child’s gut.
Why it matters
You can’t change genes, but you can lower prenatal stress. Teach OB clinics to screen for the short 5-HTTLPR allele and offer extra support during the first two trimesters. A short mindfulness course or brief respite visits may cut later ASD risk for these moms.
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02At a glance
03Original abstract
Stress exposure during gestation is implicated in several neuropsychiatric conditions, including autism spectrum disorder (ASD). Previous research showed that prenatal stress increases risk for ASD with peak exposure during the end of the second and the beginning of the third trimester. However, exposures to prenatal stress do not always result in ASD, suggesting that other factors may interact with environmental stressors to increase ASD risk. The present study examined a maternal genetic variation in the promoter region of the serotonin transporter gene (5-HTTLPR) affecting stress tolerance and its interaction with the effect of environmental stressors on risk for ASD. Two independent cohorts of mothers of ASD children recruited by the University of Missouri and Queen's University were surveyed regarding the prenatal environment and genotyping on 5-HTTLPR was performed to explore this relationship. In both samples, mothers of children with ASD carrying the stress susceptible short allele variant of 5-HTTLPR experienced a greater number of stressors and greater stress severity when compared to mothers carrying the long allele variant. The temporal peak of stressors during gestation in these mothers was consistent with previous findings. Additionally, increased exposure to prenatal stress was not reported in the pregnancies of typically developing siblings from the same mothers, regardless of maternal genotype, suggesting against the possibility that the short allele might increase the recall of stress during pregnancy. The present study provides further evidence of a specific maternal polymorphism that may affect the risk for ASD with exposure to prenatal stress. Autism Res 2016, 9: 1151-1160. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.
Autism research : official journal of the International Society for Autism Research, 2016 · doi:10.1002/aur.1629