HTR5A and mental disorder: The two receptors converge on common end points in 5HT cell signaling (Barnes and Sharp 1999; Morin et al. 1992; Rovescalli et al. 1993) and are key players in 5HT-related mental disorders (Arango et al. 2001; Fujita et al. 2000; Yatham et al. 1999, 2000); the 5HT transporter regulates the synaptic concentration of 5HT and is the major target for antidepressant drugs (Maes and Meltzer 1995; Nemeroff 1998; Nutt 2002).