Association Analysis between Chromogranin B Genetic Variations and Smooth Pursuit Eye Movement Abnormality in Korean Patients with Schizophrenia

OBJECTIVES: According to previous studies, the Chromogranin B (CHGB) gene could be an important candidate gene for schizophrenia which is located on chromosome 20p12.3. Some studies have linked the polymorphism in CHGB gene with the risk of schizophrenia. Meanwhile, smooth pursuit eye movement (SPEM) abnormality has been regarded as one of the most consistent endophenotype of schizophrenia. In this study, we investigated the association between the polymorphisms in CHGB gene and SPEM abnormality in Korean patients with schizophrenia. METHODS: We measured SPEM function in 24 Korean patients with schizophrenia (16 male, 8 female) and they were divided according to SPEM function into two groups, good and poor SPEM function groups. We also investigated genotypes of polymorphisms in CHGB gene in each group. A logistic regression analysis was performed to find the association between SPEM abnormality and the number of polymorphism. RESULTS: The natural logarithm value of signal/noise ratio (Ln S/N ratio) of good SPEM function group was 4.19 ± 0.19 and that of poor SPEM function group was 3.17 ± 0.65. In total, 15 single nucleotide polymorphisms of CHGB were identified and the genotypes were divided into C/C, C/R, and R/R. Statistical analysis revealed that two genetic variants (rs16991480, rs76791154) were associated with SPEM abnormality in schizophrenia (p = 0.004). CONCLUSIONS: Despite the limitations including a small number of samples and lack of functional study, our results suggest that genetic variants of CHGB may be associated with SPEM abnormality and provide useful preliminary information for further study.

No Association between (AAT)n Repeat Polymorphisms in the Cannabinoid Receptor 1 Gene and Smooth Pursuit Eye Movement Abnormality in Korean Patients with Schizophrenia

OBJECTIVES: According to previous studies, the cannabinoid receptor 1 (CNR1) gene could be an important candidate gene for schizophrenia. Some studies have linked the (AAT)n trinucleotide repeat polymorphism in CNR1 gene with the risk of schizophrenia. Meanwhile, smooth pursuit eye movement (SPEM) has been regarded as one of the most consistent endophenotypes of schizophrenia. In this study, we investigated the association between the (AAT)n trinucleotide repeats in CNR1 gene and SPEM abnormality in Korean patients with schizophrenia. METHODS: We measured SPEM function in 167 Korean patients with schizophrenia (84 male, 83 female) and they were divided according to SPEM function into two groups, good and poor SPEM function groups. We also investigated allele frequencies of (AAT)n repeat polymorphisms on CNR1 gene in each group. A logistic regression analysis was performed to find the association between SPEM abnormality and the number of (AAT)n trinucleotide repeats. RESULTS: The natural logarithm value of signal/noise ratio (Ln S/N ratio) of the good SPEM function group was 4.34 ± 0.29 and that of the poor SPEM function group was 3.21 ± 0.70. In total, 7 types of trinucleotide repeats were identified, each containing 7, 10, 11, 12, 13, 14, and 15 repeats, respectively. In the patients with (AAT)₇ allele, the distributions of the good and poor SPEM function groups were 18 (11.1%) and 19 (11.0%) respectively. In the patients with (AAT)₁₀ allele, (AAT)₁₁ allele, (AAT)₁₂ allele, (AAT)₁₃ allele, (AAT)₁₄ allele and (AAT)₁₅ allele, the distributions of good and poor SPEM function groups were 13 (8.0%) and 12 (7.0%), 4 (2.5%) and 6 (3.5%), 31 (19.8%) and 35 (20.3%), 51 (31.5%) and 51 (29.7%), 36 (22.2%) and 45 (26.2%), 9 (5.6%) and 4 (2.3%) respectively. As the number of (AAT) n repeat increased, there was no aggravation of abnormality of SPEM function. CONCLUSIONS: There was no significant aggravation of SPEM abnormality along with the increase of number of (AAT)n trinucleotide repeats in the CNR1 gene in Korean patients with schizophrenia.

No Association between Val108/158Met Polymorphism on Catechol-O-Methyl Transferase(COMT) Gene and Smooth Pursuit Eye Movement(SPEM) Abnormality in Korean Schizophrenia Patients

OBJECTIVES: We investigated the association of Val108/158Met polymorphism on catechol-O-methyl transferase(COMT) gene with smooth pursuit eye movement(SPEM) abnormality in Korean schizophrenia patients. METHODS: We measured SPEM in 217 Korean schizophrenia patients(male 116, female 101) and divided them into two groups, one was a good SPEM function group and the other was a poor SPEM function group. Then we analyzed Val108/158Met polymorphism on COMT gene. We compared the differences of genotype and allele distributions of the polymorphism on COMT gene between the two groups. RESULTS: The natural logarithm value of signal/noise ratio(Ln S/N ratio) of the good SPEM function group was 4.39+/-0.33(mean+/-s.d.) and that of poor SPEM function group was 3.17+/-0.71. There were no statistically significant differences of age and male/female ratio between the two groups. There were no significant differences of genotype or allele distributions of the Val108/158Met polymorphism on COMT gene between the two schizophrenic groups. CONCLUSIONS: The results suggest that Val108/158Met polymorphism on COMT gene is not related to SPEM function abnormality in schizophrenia.

Relationship between SNP A and P1763 Polymorphisms on Dystrobrevin Binding Protein 1(DTNBP1) Gene and Smooth Pursuit Eye Movement(SPEM) Abnormality in Korean Schizophrenic Patients

OBJECTIVES: We investigated the association of SNP A and P1763 polymorphisms on dystrobrevin binding protein 1(DTNBP1) gene with smooth pursuit eye movement(SPEM) abnormality in Korean schizophrenic patients. METHODS: We measured SPEM function in 217 Korean schizophrenics(male 116, female 101) and divided them into two groups, one is a good SPEM function group and the other is a poor SPEM function group. We then analyzed SNP A polymorphism and P1763 polymorphism on DTNBP1 gene from their DNAs extracted from their blood. We compared the differences of genotype and allele distributions of the two polymorphisms on DTNBP1 gene between the two groups. RESULTS: The Ln S/N ratio(mean+/-SD) of the good SPEM function group was 4.39+/-0.33 and the ratio of poor SPEM function group was 3.17+/-0.71. There were no statistically significant differences of age and male/female ratio between the two groups. There were no significant differences of genotype or allele distributions of the SNP A polymorphism and P1763 polymorphism on DTNBP1 gene between the two schizophrenic groups divided by SPEM function. CONCLUSION: The results suggest that SNP A polymorphism and P1763 polymorphism on DTNBP1 gene might not be related to SPEM function abnormality in schizophrenia.

Association Analysis between P1635 and P1655 Polymorphisms on Dystrobrevin Binding Protein 1(DTNBP1) Gene and Smooth Pursuit Eye Movement(SPEM) Abnormality in Korean Schizophrenia Patients / 대한정신약물학회지

OBJECTIVE: We investigated the association of P1635 and P1655 polymorphisms on dystrobrevin binding protein 1 (DTNBP1) gene with smooth pursuit eye movement (SPEM) abnormality in Korean schizophrenia patients. METHODS: We measured SPEM function in 216 Korean schizophrenia patients (male 116, female 100) and divided them into two groups, one is a good SPEM function group and the other is a poor SPEM function group. We then analyzed P1635 polymorphism and P1655 polymorphism on DTNBP1 gene from their DNAs extracted from their blood. We compared the differences of genotype and allele distributions of the two polymorphisms on DTNBP1 gene between the two groups. RESULTS: The Ln S/N ratio (mean+/-sd) of the good SPEM function group was 4.39+/-0.33 and the ratio of poor SPEM function group was 3.18+/-0.71. There were no statistically significant differences of age and male/female ratio between the two groups. There were no significant differences of genotype or allele distributions of the P1635 polymorphism and P1655 polymorphism on DTNBP1 gene between the two schizophrenia groups divided by SPEM function. CONCLUSION: The results suggest that P1635 polymorphism and P1655 polymorphism on DTNBP1 gene might not be related to SPEM function abnormality in schizophrenia.

Improvement of Smooth Pursuit Eye Movements after Cigarette Smoking in Chronic Schizophrenic Patients

This study was done to examine whether cigarette smoking improved smooth pursuit eye movement(SPEM) abnormalities in chronic schizophrenic inpatients. Fifteen schizophrenic and twelve alcoholic subjects abstained from their usual cigarette smoking for a minimum of nine hours and their baseline performances during the constant velocity smooth pursuit tasks were assessed. Then, the subjects smoked as much as they desired in a 10 minutes period and were retested immediately after smoking and 15 minutes after smoking. Electrooculographic recordings during the eye movements were converted and saved as digitized files. Power spectral density curves and natural logarithm value of signal/noise(Ln S/N) ratios were computed from them. In the schizophrenic patients, Ln S/N ratios increased significantly immediately after smoking compared to baseline. But Ln S/N ratios showed no statistically significant changes after 15 minutes compared to baseline. In alcoholic subjects Ln S/N ratios showed no statistically significant changes immediately after smoking and after 15 minutes compare to baseline. In conclusion, SPEM was improved in schizophrenic patients immediately after smoking and we hypothesized that nicotinic receptor dysfunction maybe a candidate mechanism for smooth pursuit eye movement abnormalities in schizophrenia.