Montgomery AK, et al. - Considering the implication of the serotonin (5-HT) system in autism spectrum disorder (ASD) and the possible influence of the maternal 5-HT system on embryonic neurodevelopment seen in recent findings, researchers examined the relationship between maternal whole blood 5-hydroxytryptamine level (WB5-HT) and ASD phenotypes. They obtained WB5-HT levels from 181 individuals (aged between 3 and 27 years) diagnosed with ASD, 99 of their fathers, and 119 of their mothers. Outcomes suggest that maternal WB5-HT influence the neurodevelopmental outcomes in offspring with ASD. A three-class structure in the assessment data was identified by latent class analysis, describing children with low, intermediate, and high severity across measures of behavior, cognition, and adaptive function. Across classes, mean maternal WB5-HT differed with the lowest maternal WB5-HT levels seen in the highest severity group.