ELEVATED SEROTONIN LEVELS IN AUTISM - ASSOCIATION WITH THE MAJOR HISTOCOMPATIBILITY COMPLEX

Two of the most consistently observed biological findings in autism ar e increased serotonin levels in the blood and immunological abnormalit ies (including autoreactivity with tissues of the central nervous syst em). The purpose of this investigation was to determine if any relatio nship exists between these two sets of observations. Our laboratory ha s found and confirmed associations of the major histocompatibility com plex (MHC) with autism. Since the MHC is known to regulate the immune system and is also associated with autoimmune disorders, we studied se rum serotonin levels in 20 autistic subjects with or without MHC types previously found to be associated with autism. A positive relationshi p was observed between elevated serotonin levels and the MHC types pre viously associated with autism.