- A serine to glycine substitution at position 9 in the extracellular N-terminal part of the dopamine D3 receptor protein: no role in the genetic predisposition to bipolar affective disorder. Rietschel, M., Nöthen, M.M., Lannfelt, L., Sokoloff, P., Schwartz, J.C., Lanczik, M., Fritze, J., Cichon, S., Fimmers, R., Körner, J. Psychiatry research. (1993)