Page by Stephanie Watkins
In 1997, following the trend of attempting to locate a molecular basis of autism, it was hypothesized that the serotonin transporter gene (HHT) may play a role. The risk of recurrence is high among siblings, following twin studies establishing greater prevalence among monozygotic twins (identical) versus dizygotic twins (fraternal). After a 1961 study found increased serotonin in blood in children with autism, various other studies replicated this idea in other species as well. Serotonin transport inhibitors have also been linked to restricted and repetitive behaviors associated with anxiety and/or aggression, furthering the theoretical support for the connection of serotonin to autism. A study by Cook et al. demonstrated that two serotonin transport genetic markers were associated with autism, most specifically the short variant (previously linked to anxiety) of the serotonin transport gene being transmitted from parent to child. However, the study’s discussion stated that the short variant of the serotonin transport gene may serve as a susceptibility locus in which additional genetic or environmental factors must be present in order for autism to express itself (Cook, Courchesne, Lord, Cox, Yan, Lincoln, Haas, Courchesne, & leventhal, 1997).
Cook, E. H., Courchesne, R., Lord, C., Cox, N. J., Yan, S., Lincoln, A., Haas, R., Courchesne, E., & Leventhal, B. L. (1997). Evidence of linkage between the serotonin transporter and autistic disorder. Molecular Psychiatry, 2, 247-250.