Platelet serotonin, a possible marker for familial autism.
High platelet serotonin may flag familial autism risk, but the measure is not ready for clinic use.
01Research in Context
What this study did
Researchers drew blood from three groups of kids. Group one had autism plus an autistic sibling. Group two had autism but no affected siblings. Group three were typical kids with no autism in the family.
They measured serotonin levels in each child's platelets. Then they compared the three groups to see if serotonin could act like a red flag for familial autism.
What they found
Kids with autism and an affected sibling had the highest serotonin. Kids with autism but no affected siblings came next. Typical kids had the lowest levels.
The pattern suggests high platelet serotonin runs in autism families, making it a possible biological marker for inherited risk.
How this fits with other research
Hranilovic et al. (2007) repeated the same finding in autistic adults, showing the serotonin signal persists past childhood.
Goldberg et al. (2009) flipped the lens to parents. They found lower cortical serotonin-2 receptors in moms and dads of autistic kids. This looks opposite to high platelet serotonin, but it actually points to the same system working differently in various family members.
Palka Bayard de Volo et al. (2021) moved beyond biology and showed that autism trait scores themselves are strongly heritable in adults. Together, these papers build a picture: autism risk travels in families through both behavior and biology.
Why it matters
You cannot use a blood test for autism yet, but you can watch for early signs in younger siblings. When a family already has one autistic child, keep extra close tabs on the baby brother or sister. Track language, play, and social milestones from the first year.
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02At a glance
03Original abstract
Serotonin (5HT) levels in platelet-rich plasma were measured in 5 autistic subjects who had siblings with either autism or pervasive developmental disorder (PDD), 23 autistic subjects without affected siblings, and 10 normal controls. The 5HT levels of autistic subjects with affected siblings were significantly higher than probands without affected siblings, and autistic subjects without affected siblings had 5HT levels significantly higher than controls. Differences in 5HT levels remained significant after adjustment for sex, age, and IQ. These results suggest that 5HT level in autistic subjects may be associated with genetic liability to autism.
Journal of autism and developmental disorders, 1991 · doi:10.1007/BF02206997