[Platelet serotonin concentrations in autistic children and members of their families].

Children with early infantile autism have often high platelet serotonin (5 HT) levels. According to this fact, we wondered if a genetic abnormality of 5 HT metabolism could be detected in family members of autistic children. We has thus determined platelet 5 HT levels in these children's mothers, fathers and siblings. It is noteworthy to find out that: autistic children have a mean platelet 5 HT level significantly higher than their siblings' (p less than 0.01); fathers' levels are significantly lower (-29%; p less than 0.001) than those of other family members' and of control group. Furthermore, for future purposes, we studied platelet 5 HT levels at different times during pregnancy in controls and in a woman already mother of an autistic child. We observed a raise (+31%; p less than 0.01) in platelet 5 HT during the first trimester of the pregnancy with a lowering towards normal levels during the eight month, in the woman with an autistic child as well as in the controls.