POLYMORPHISMS OF DOPAMINE D2-LIKE (D2, D3, AND D4) RECEPTORS IN SCHIZOPHRENIA

The result of most association. studies and linkage analyses have sugg ested a negative association. between schizophrenia and D2-like (D2, D 3, and D4) receptor polymorphisms. Although the polymorphisms of the D 2-like receptor in themselves may not account for the etiology of schi zophrenia, they can contribute to the severity of the symptoms. Thus, we studied the associations between the polymorphisms and their combin ations, and the vulnerability of schizophrenics. Fragments of the D2-l ike receptor genes were amplified by means of the polymerase chain rea ction, and the polymorphisms were identified by the restriction fragme nt length polymorphism and single-stranded conformation polymorphism m ethods. There were no statistically significant differences in the pol ymorphisms and their combinations between schizophrenics and controls. Schizophrenics with D4E1(A1/A2) which contains 2 and 1 tandem repeats of a 12-base-pair sequence in exon 1, had a lower total positive symp tom score before medication than schizophrenics with D4E1(A1/A1). Ther e was no association between the polymorphisms and negative symptoms. (C) 1996 Society of Biological Psychiatry