Several observations informed this question, including the fact that reelin is highly expressed in blood plasma (Smalheiser et al., 2000), that plasma reelin is altered in mood and psychotic disorders (Fatemi et al., 2001a), that reelin induces clustering of its own receptors receptors and this is an important event for signaling (Strasser et al., 2004), and that lymphocytes contain reelin receptors whose expression is changed in psychiatric disorders (Suzuki et al., 2008). This evidence concerns the gene RELN and psychiatric disorder.