- Serotonin transporter (5-HTT) gene polymorphisms are not associated with susceptibility to mood disorders. Hoehe, M.R., Wendel, B., Grunewald, I., Chiaroni, P., Levy, N., Morris-Rosendahl, D., Macher, J.P., Sander, T., Crocq, M.A. Am. J. Med. Genet. (1998)