• Korean Journal of Biological Psychiatry
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• v.12 no.2
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• pp.107-113
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• 2005

Purpose:In an attempt to predict the interpersonal differences of therapeutic response to antipsychotic drugs on pharmaco-genetic bases, this study was designed to investigate the relationship between the therapeutic response to antipsychotic drugs and Taq I A dopamine $D_2$ receptor polymorphism in schizophrenic patients. Methods:The subjects were 158 patients diagnosed with schizophrenia(DSM-IV). The therapeutic response to antipsychotic drugs was evaluated using the Treatment Response Scale(TRS) retrospectively. Patients were divided into two groups, dopamine receptor antagonist responders, and serotonin-dopamine antagonist responders. The patients' Taq I A dopamine $D_2$ receptor polymorphism was determined by polymerase chain reaction(PCR) and restriction fragment length polymorphism(RFLP). Results:The dopamine receptor antagonist responders had the A1 allele in significantly higher incidences (${\chi}^2$(1)=4.875, p=0.027, two-tailed). No significant difference was found among the serotonin-dopamine antagonist responders between those with or without the A1 allele. Conclusions:The patients with the A1 allele responded better to dopamine receptor antagonists than those with no A1 allele. Based on these results, it is suggested that the pharmacological effect of dopamine receptor antagonists can be predicted depending on the presence of the A1 allele in schizophrenic patients.

• Korean Journal of Biological Psychiatry
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• v.4 no.2
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• pp.225-233
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• 1997

The authors attempted to examine the allelic association between the A1 allele of Dopamine $D_2$ receptor and schizophrenia, alcoholism, drug addiction in Koreans. Schizophrenic patients(n=31), alcoholism(n=65), drug addiction(n=18) and controls(n=52) were examined by case-control study for distribution of the TaqI polymorphism of the dopamine $D_2$ receptor gene in Korean population to minimize the effect of racial differencies in gene frequencies. In schizophrenics, the numbers of schizophrenics with A1A1, A1A2, A2A2 were 9(29.0%), 15(48.4%) and 7(22.6%) respectively and in alcoholics with A1A1, A1A2, A2A2 were 14(21.5%), 36(55.4%) and 15(23.1%) respectively and in drug addiction with A1A1, A1A2, A2A2 were 2(11.1%), 10(55.6%) and 6(33.3%) respectively and in controls with A1A1, A1A2, A2A2 were 4(7.6%), 24(46.2%) and 24(46.2%) respectively. The prevalence of the A1 allele in schizophrenics, alcoholics, drug addiction and controls were 77%, 76.9%, 67% and 53.8% respectively. And the frequency of the A1 allele in schizophrenics, alcoholics, drug addiction and controls were 0.53, 0.49 0.39 and 0.31 respectively. There was significant difference in the frequency of the A1 allele between schizophrenics, alcoholics and controls. We also classified our alcoholic population. For classification by severity, we used the median MAST score 30 in our samples. There was also significant difference in the frequency of the A1 allele between less severe group(0.42) and more severe group(0.57). This data suggest that the A1 allele is associated with schizophrenia and alcoholism in Koreans. Furthermore the prevalence of the A1 allele increassed in more severely affected alcoholics. The authors conclude that our data support an allelic association between the A1 allele at dopamine $D_2$ receptor and schizophrenia, alcoholism. These results suggest the A1 allele of the $DRD_2$ gene is associated with a number of behavior disorders in which it may act as a modifying gene rather than as the primary etiological agent.

• Korean Journal of Biological Psychiatry
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• v.4 no.1
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• pp.43-47
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• 1997

The author attempted to examine the allelic association between the A1 allele of Dopamine $D_2$ receptor and alcoholism in Koreans. The allelic distribution of Taq I polymorphism of the $D_2$ dopamine receptor gene with alcoholism was examined in 67 Korean alcoholics and compared with 100 Korean controls. In alcoholics, the numbers of alcoholics with A1A1, A1A2 and A2A2 were 11(16.4%), 30(44.8%) and 26(38.8%) respectively and in controls with A1A1, A1A2 and A2A2 were 17(17.0%), 42(42.0%) and 41(41.0%), respectively. The prevalence of the A1 allele in alcoholics was 61.2% and 59.0% in controls. And the frequency of the A1 allele in alcoholics and controls were 0.39 and 0.38, respectively. There was not significant difference in the frequency of the A1 allele between alcoholics and controls. This data suggest that the A1 allele is not associated with alcoholism in Koreans. The author conclude that our data do not support an allelic association between the A1 allele at Dopamine $D_2$ receptor and alcoholism. Further systemized studies will be necessary to determine whether the role of allele of Dopamine $D_2$receptor is major effect gene or modifying effect gene in the pathogenesis of alcoholism.

• Korean Journal of Biological Psychiatry
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• v.18 no.2
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• pp.101-108
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• 2011

Objectives The aim of this study is to explore the association among DRD4 polymorphism, temperament and alcohol drinking behavior of Koreans in their early adulthood. Method Participants were 172 healthy Korean adults (mean age $28.1{\pm}0.8$). Their temperament was assessed with the Temperament and Character Inventory (TCI) and their alcohol drinking behavior were evaluated with a self-reported questionnaire including the CAGE and the Korean version of Alcohol Use Disorder Identification Test (AUDIT-K). DRD4 exon III 48 base pair variable number of tandem repeats (VNTR) was genotyped by PCR. Results No significant association was found between DRD4 polymorphism and TCI temperament dimension (novelty seeking, harm avoidance, reward dependence, and persistence) as well as alcohol drinking behavior scales. However, novelty seeking was significantly associated with alcohol drinking behavior. The higher level of novelty seeking was associated with the higher severity index of drinking (B = -0.225, p < 0.001) and problematic alcohol use on the CAGE and AUDIT-K [Odds Ratio (OR) = 1.111, 95% Confidence Interval (CI) 1.021-1.209, p = 0.015, OR = 1.087, 95% CI 1.009-1.170, p = 0.028]. Conclusion In our study, while there is no significant association of DRD4 polymorphism with temperament and alcohol drinking behavior, novelty seeking affects problematic alcohol use. Results suggest that novelty seeking may play an important role in problematic alcohol use in young Korean adults.

• Korean Journal of Biological Psychiatry
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• v.9 no.1
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• pp.15-24
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• 2002

Even though alcoholism is a multi-factorial psychiatric disorder, it is reasonable to suppose that genetic factors play a substantial role in the manifestation of this disorder. Because alcohol is the reinforcing substance which manifests its effects through activation of the mesolimbic dopaminergic reward pathway of the brain, the gene encoding dopamine receptor subtypes can be a major natural candidate gene. Since 1990, many association studies have identified strong evidence implicating the dopamine D2 receptor(DRD2) gene in alcoholism, specifically TaqI A minor(A1) allele. Association studies have also been conducted on other dopamine receptor(DRD3 & DRD4) polymorphisms but the results have yet to be confirmed. Through a number of other approaches, each dopamine receptor gene has been investigated in association with different phenotypes in alcoholism, but further researches will be needed. In conclusion, studies in the past decade have shown that the TaqI A1 allele of the DRD2 gene is associated with alcoholism in various subject groups. Other dopamine receptor genes have since been added to the list but yet to be identified. Thus, the knowledge of these genes and their functional significance will enhance the understanding of the underlying biological mechanisms of alcoholism. Furthermore, it could lead to more helpful prevention and treatment approaches to alcoholism.

• Korean Journal of Biological Psychiatry
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• v.13 no.4
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• pp.299-304
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• 2006

Objectives : The purpose of the present study was to investigate whether the TaqI A polymorphism of dopamine receptor D2 gene(DRD2) is associated with Tourette syndrome(TS) and chronic motor tic disorder(CMT) in Korean population. Methods : DRD2 TaqI A RFLP genotyping was carried out with DNA extracted from blood samples of 75 patients with tic disorders(47 with TS and 28 with CMT) and 90 healthy subjects. Genotype and allelic frequencies for the DRD2 gene polymorphisms of the tic disorder group as a whole were compared to those of the control group. Separating the TS group, thereafter, the frequency of genotypes and alleles were compared to those of the controls. Results : The results demonstrated that genotype and allele distributions for the DRD2 gene polymorphism in the tic disorder as a whole, TS, and control groups were not significantly different. Conclusion : No association was found for DRD2 gene, TS and CMT. The data suggest that DRD2 gene may not be a useful marker for the prediction of the susceptibility of tic disorder.

• Korean Journal of Biological Psychiatry
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• v.7 no.2
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• pp.152-158
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• 2000

Background : No association between schizophrenia and dopamine D4 receptor polymorphisms have been reported. Despite these results, it is premature to exclude the association. It has been suggested that the susceptibility to develop schizophrenia could result from variation at a number loci which may interact or coact with each other. Therefore, we investigated a possible association of combinations of exon III 48bp polymorphism[D4E3] and exon I 12bp polymorphism of the DRD4 gene [D4E1] with schizophrenia. Methods : 207 unrelated Korean schizophrenic patients and 191 healthy controls were recruited. DRD4 genotype was established using the polymerase chain reaction. Statistical analysis consisted of ${\chi}^2$ tests for Hardy-Weinberg proportions and genotypic and allelic frequencies in the patients and control groups. Results : There were no statistically significant differences in the each polymorphisms between schizophrenics and controls. And all genotype frequencies were within Hardy-Weinberg expectations. When the combinations of the polymorphism in schizophrenia and controls were compared, however, there were significant differences at $A1A2^*2/4$ in the distributions of the combinations of D4E1 and D4E3(p<0.01). Conclusions : These findings suggest that the certain combination of D4E1 and D4E3($A1A2^*2/4$) has the protective role to a susceptibility for schizophrenia.

• The Korean Journal of Nuclear Medicine
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• v.39 no.6
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• pp.413-420
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• 2005

Purpose: Neuroreceptor PET studies require 60-120 minutes to complete and head motion of the subject during the PET scan increases the uncertainty in measured activity. In this study, we investigated the effects of the data-driven head mutton correction on the evaluation of endogenous dopamine release (DAR) in the striatum during the motor task which might have caused significant head motion artifact. Materials and Methods: $[^{11}C]raclopride$ PET scans on 4 normal volunteers acquired with bolus plus constant infusion protocol were retrospectively analyzed. Following the 50 min resting period, the participants played a video game with a monetary reward for 40 min. Dynamic frames acquired during the equilibrium condition (pre-task: 30-50 min, task: 70-90 min, post-task: 110-120 min) were realigned to the first frame in pre-task condition. Intra-condition registrations between the frames were performed, and average image for each condition was created and registered to the pre-task image (inter-condition registration). Pre-task PET image was then co-registered to own MRI of each participant and transformation parameters were reapplied to the others. Volumes of interest (VOI) for dorsal putamen (PU) and caudate (CA), ventral striatum (VS), and cerebellum were defined on the MRI. Binding potential (BP) was measured and DAR was calculated as the percent change of BP during and after the task. SPM analyses on the BP parametric images were also performed to explore the regional difference in the effects of head motion on BP and DAR estimation. Results: Changes in position and orientation of the striatum during the PET scans were observed before the head motion correction. BP values at pre-task condition were not changed significantly after the intra-condition registration. However, the BP values during and after the task and DAR were significantly changed after the correction. SPM analysis also showed that the extent and significance of the BP differences were significantly changed by the head motion correction and such changes were prominent in periphery of the striatum. Conclusion: The results suggest that misalignment of MRI-based VOI and the striatum in PET images and incorrect DAR estimation due to the head motion during the PET activation study were significant, but could be remedied by the data-driven head motion correction.

• Anxiety and mood
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• v.4 no.2
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• pp.142-147
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• 2008

Objective : Evidence from recent studies supports the role of genetic factors in the development of Posttraumatic Stress Disorder (PTSD). The primary aim of this study is to investigate the association between the dopamine D2 receptor (DRD2) TaqI A polymorphism and PTSD. The second aim is to examine the association between the DRD2 TaqI A polymorphism and clinical symptoms in patients with PTSD. Methods : We recruited 189 Vietnam veterans for participation in this study, among whom 99 were PTSD patients and 90 were control subjects. The presence of the DRD2 TaqI A polymorphism was determined by polymerase chain reaction (PCR). Several standardized research scales were used in the clinical assessment of PTSD, including the Combat Exposure Scale (CES), Clinician Administered PTSD Scale (CAPS), Beck Depression Inventory (BDI), and Clinical Global Impression (CGI). Results : There was no significant difference in the distribution of the DRD2 genotype, frequency and prevalence of the A1 allele, or the frequency of heterozygotes between the patients with PTSD and the controls. In the PTSD group, the patients with the A1 allele (A1A1, A1A2) scored higher on the CAPS-total (p=0.044), CAPS-avoidance symptoms (p=0.016) and BDI (p=0.024) than those without the A1 allele (A2A2). Conclusion : We could not find an association between the dopamine D2 receptor (DRD2) TaqI A polymorphism and PTSD. However, the A1 allele of DRD2 seemsto influence avoidance symptoms in patients with PTSD.

• Anxiety and mood
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• v.2 no.1
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• pp.45-49
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• 2006

Puropse : Disturbances of dopaminergic system might be related to the possible mechanism of panic disorder. This study was aimed to examine the association of DRD2 Taq 1 polymorphism and panic disorder. Methods : One hundred and fourteen patients with panic disorder (62 male (54.4%), mean age $40.96{\pm}0.11$ years) and 200 comparison subjects (114 male (57.0%), mean age $35.57{\pm}8.81$ years)were tested for DRD2 TaqI A polymorphism. We excluded panic patients with comorbid alcohol related disorders, bipolar disorders, and any kinds of psychotic disorders because there have been some reports about association of these disease and DRD2 TaqI A polymorphism. Results : There was significant difference in the frequency of the genotype in DRD2 polymorphism between patients and controls (${\chi}^2$=6.09, df=2, p=0.048). The A1+ allele (A1A1 and A1A2) frequency analysis also showed significant association (${\chi}^2$=4.08, df=1, p=0.043). In addition, we observed a more strong and specific association between panic disorder and the A1+ allele of the DRD2 TaqI polymorphism for men (${\chi}^2$=4.71, df=1, p=0.03), but not for women (${\chi}^2$=0.45, df=1, p=0.50). Conclusion : These results in our Korean sample suggest that the DRD2 TaqI A polymorphism may be associated with panic disorder. Furthermore, we found sex-specific association of DRD2 A1 allele with panic disorder.