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

ABSTRACT

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.