“…Elevation of serotonin is present in family members of autistic subjects with hyperserotonemia [Kuperman et al, 1985; Abramson et al, 1989; Cook et al, 1990, 1994; Leventhal et al, 1990; Piven et al, 1991]. Pharmacologic studies implicate the serotonin system in autism [Cook et al, 1994; McDougle et al, 1996; Potenza and McDougle, 1997]. In addition to recent genome‐wide linkage findings on 17q, there is specific evidence for the involvement of the serotonin transporter protein gene on 17q (HTT) [Cook et al, 1997; Klauck et al, 1997; Marazziti et al, 2000; Yirmiya et al, 2001, Tordjman et al, 2001; Kim et al, 2002].…”