• Korean Journal of Biological Psychiatry
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• v.4 no.2
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• pp.218-224
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• 1997

The results regarding an association between the polymorphism sites in the dopamine $D_1$ receptor gene and schizophrenia compelled us to study the distribution of the polymorphism in Korean schizophrenia and controls. Eighty-eight schizophrenic patients and normal controls were examined by case-control study for distribution of the polymorphism of the dopamine $D_1$ receptor gene in Korean popualtion to minimize the effect of racial differencies in gene frequencies. The frequencies of the $B_1$ and $B_2$ in schizophrenic patients were 0.11 and 9.89, respectively. And 0.10 and 0.90 in normal control. Ther was no significant differences in the frequencies in the allele $B_1$ and $B_2$between schizophrenic patients and normal controls. The author present here the evidence of a lack of alleic association between the polymorphism of the dopamine $D_1$ receptor gene and Korean schizophrenic patients. The assumption that the dopamine $D_1$ receptor gene has a genetic role in the development of schizophrenia was not suppoorted by this case-control study.

• Korean Journal of Biological Psychiatry
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• v.8 no.1
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• pp.111-115
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• 2001

An association study with Korean alcoholic patients(n=50) and normal controls(n=53) was performed to find the relationship between catechol-O-methyltransferase(COMT) gene polymorphism and alcoholism using polymerase chain reaction-restriction fragment length polymorphism. When we compared the allele and genotype frequencies of Nla III COMT gene polymorphism in alcoholism and normal controls, there was no significant difference between two groups. Our results do not support an association between the Nla III polymorphism of COMT gene and alcoholism.

• 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.5 no.2
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• pp.210-214
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• 1998

An association study with Korean schizophrenic patients(N=84) and normal controls(N=87) was performed to find the relationship between catechol-O-methyltransferase(COMT) gene polymorphism and schizophrenia using polymerase chain reaction-restriction fragment length polymorphism. When we compared the allele and genotype frequencies of Bgl I COMT gene polymorphism in schizophrenics and normal controls, there was no significant difference between two groups. Our results do not support an association between the Bgl I polymorphism of COMT gene and schizophrenia.

• Korean Journal of Biological Psychiatry
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• v.2 no.2
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• pp.237-247
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• 1995

The finding of contrasting results regarding an association between schizophrenia and the Mlul polymorphism site in the dopamine $D_3$ receptor gene prompted us to study the distribution of this palymorphism in Korean schizophrenic patients and controls. The author's approach was case-control study. Schizophrenic patients (n=66) and controls (n=76) were examined by case-control study for distribution of the Mlul polymorphism of the dopamine $D_3$ receptor gene in Korean population to minimize the effect of racial differencies in gene frequencies. The frequency of the allele 1 in schizophrenic patients and controls was 0.66 and 0.76, respectively. There was no significant differencies in the frequency of the allele 1 between schizophrenic patients and controls ($x^2$=3.07, p>.05), and between positive and negative schizophrenic patients ($x^2$=1.02, p>.05). We present here the evidence of a lack of alleic association between the Mlul polymorphism of the dopamine $D_3$ receptor gene and Korean schizophrenic patients and also report no increased homozygosity for the Mlul polymorphism. The assumption that the dopamine $D_3$ receptor gene has a predisposing role in schizophrenia was not supported by this case-control study. Although, the possibility that this gene has a minor gene effects in the etiology of schizophrenia cannot be excluded because of the intrinsic limitations of the methods of analysis and number of subjects in our study.

• Korean Journal of Biological Psychiatry
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• v.9 no.1
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• pp.62-67
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• 2002

Objective:There is increasing evidence that free radical-mediated CNS neuronal dysfunction is involved in the pathophysiology of schizophrenia. This study was performed to examine the relationship between antioxidant defense system and schizophrenia by analyzing polymorphism of catalase gene, an antioxidant enzyme. Method:Genotype and allele frequencies in the promoter region in the catalase gene using restriction fragment length polymorphism were studied, comparing 155 Korean controls with 167 Korean schizophrenics. Results:No difference was found between the schizophrenics and the controls in genotype and allele frequencies of HinfI polymorphism in the catalase gene. Significant difference was found between the female schizophrenics and the female controls in the genotype distribution(${\chi}^2$=11.096, df=2, p=0.004). Conclusions:The results do not support an association between polymorphism of catalase gene and schizophrenia. However, this study suggests that HinfI polymorphism in the catalase gene could be associated with female schizophrenics.

• Korean Journal of Biological Psychiatry
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• v.3 no.2
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• pp.162-169
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• 1996

An association study with korean schizophrenic patients(N=75) and normal controls(N=87) was performed to find the relationship between D6S274 polymorphism and schizophrenia using polymerase chain reaction. Nine different alleles of a dinucleotide polymorphism on D6S273 locus were observed in both group. When we compared the frequencies of alleles between schizophrenics and normal controls, there was no significant difference between two groups. To increase homogeneity of schizophrenic group, we divided schizophrenic group by clinical phenotypes such as DSM-IV diagnostic subtype, family history, negative and positive symptoms(PANSS), soft neurologic signs(NES-K). Then we compared the frequencies of alleles among subgroups of clinical phenotypes. there was only significant difference between two subgroups on soft neurologic signs(p<0.05). Although our findings fail to provide on evidence of association between schizophrenia and D6S274 locus, follow-up investigation of this locus may be needed in homogeneous subtypes of schizophrenia and schizophrenic pedigrees.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.16 no.2
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• pp.199-210
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• 2005

Objective : Attention deficit hyperactivity disorder(ADHD) affects $5-10\%$ of children in Korea, with more boys and girls being diagnosed. Despite seriousness of ADHD, little is known about its causes. From the current genetic epidemiologic studies, ADHD is known as a heritable disorder. Till now, however, there have been very few genetic studies about ADHD in Korea. The aim of the this study is to examine the association between dopamine transporter gone type 1 and ADHD using case-control design in Korean ADHD probands and normal controls. Materials and Method : Child Psychiatric Genetic research team in Seoul National University Hospital, Clinical Research Institute recruited the ADHD probands using clinical interview/observation, diverse rating scales, and neuropsychological tests. For eliminating phenocopy or ADHD, diagnosis of ADHD was based upon clinical data, psychometric data, and parent/teacher reports. Total 85 ADHD-probands were recruited as final study subjects and independent 100 normal adults participated in this study as control group. For all the ADHD probands, and controls, the 3'-UTR-VNTR polymorphism of DAT1 was analyzed. Based on the DAT1 allele and genotype informations, Chi-square test based on case-control design was performed. Results : As for genetic study, total of 85 probands and 100 controls were included for the genetic analysis. Four different alleles, 350bp (7repeat), 440bp (9repeat), 480bp (10repeat) and 520bp (11repeat) were found in DAT1 gene of study subjects. In case-control analysis, ADHD probands and parents have significantly more 9 repeat allele and 9/10 genotype. Also, The probands with 9repeat allele have more commission errors in ADS. Conclusion : The positive association between ADHD and DAT1 gene was replicated in this report like other previous results for caucasian children and Korean children with ADHD. There are ongoing studies on other candidate genes such as DRD4 and DRD5 and it would be required to explore the association of these candidate genes in Korean children with ADHD. These ongoing genetic research will contribute to the understanding of heterogenous genetic and environmental etiologies of ADHD phenotype, which will lead to the development of more comprehensive treatment and preventive interventions for ADHD.

• Sleep Medicine and Psychophysiology
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• v.15 no.1
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• pp.39-43
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• 2008

Objectives: The pathophysiology of restless legs syndrome (RLS) is not obvious, but many promising theories involve dopaminergic deficiency and genetic causes. The RLS is presumed to occur more frequently among schizophrenic patients who take antipsychotics, most of which blocks the dopamine receptors. This study aimed to investigate whether dopamine transporter gene (DAT1) 40 base pair (bp) variable number of tandem repeat (VNTR) polymorphism is associated with the antipsychotic-induced RLS in schizophrenia. Methods: We determined the diagnosis of RLS among the 190 Korean schizophrenic patients by the diagnostic criteria of the International Restless Legs Syndrome Study Group (IRLSSG). Genotyping was performed for the 40bp VNTR in DAT1 gene using polymerase chain reaction. Results: We separated the schizophrenic patients into 44 patients with RLS and 146 patients without RLS. The genotype and allele frequencies did not differ significantly between two groups. Conclusions: These results suggest that DAT1 gene 40bp VNTR is not associated with the antipsychotic-induced RLS in schizophrenia. To confirm these results, larger-scale association study is needed in the future.

• 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.