Lcc. Lim et al., NO EVIDENCE OF ASSOCIATION BETWEEN DOPAMINE D4 RECEPTOR VARIANTS AND BIPOLAR AFFECTIVE-DISORDER, American journal of medical genetics, 54(3), 1994, pp. 259-263
Disturbance in the dopamine neurotransmitter system has been implicate
d in the pathogenesis of affective disorder. In this study, we examine
the possibility that functional variants of the recently cloned dopam
ine D4 receptor gene contribute to the genetic component of manic depr
ession. The polymorphism, a 48 bp tandem repeat coding for part of the
third cytoplasmic loop, was detected using a PCR based method. In a f
irst sample of 57 patients and 59 controls, we found allele 7 to be in
excess in the patients. In contrast, allele 3 was less frequent in pa
tients. A second, larger sample of 90 patients and 91 controls was uti
lized to test these hypotheses. Data from the two samples were then po
oled together for further analyses. We calculated the power of our sam
ples, and if the frequency of 7 repeat allele obtained from sample 1 i
s true, i.e., 25% (28/114) for patients and 14% (16/118) for controls,
then the power of the combined sample is 62% at 5% (two-tailed) signi
ficance level. However, both observations were not replicated; we ther
efore conclude that variations in this repeat at the DRD4 gene do not
contribute to the genetic component of manic depression. (C) 1994 Wile
y-Liss, Inc.