Byoung Gwon Kim

No Association Between Functional Polymorphisms in COMT and MTHFR and Schizophrenia Risk in Korean Population.

OBJECTIVES Common genetic SNPs in two genes, encoding catechol-O-methyltransferase (COMT) and methylenetetrahydrofolate reductase (MTHFR), which are interconnected with COMT gene regulation, have been reported to contribute to schizophrenia risk. In this study, we evaluated the association between functional polymorphisms in COMT and MTHFR and schizophrenia risk with a case-control study in a Korean population. METHODS We performed a case-control study by genotyping analysis using 360 cases and 348 controls in Korean subjects to determine the association between functional polymorphisms in COMT and MTHFR and schizophrenia risk. RESULTS Four functional SNPs in COMT (Val158Met and rs165599) and MTHFR (C677T and A1298C) were genotyped by primer extension assay. None of the genotype distributions for the four SNPs was significantly different between cases and controls. Stratified analysis did not show any significant gender difference for any polymorphism. In addition, we found no evidence of a gene-gene interaction in the analysis of combined genotypes. CONCLUSION Our results suggest no significant association between the selected functional polymorphisms of COMT or MTHFR in Korean schizophrenia subjects. However, further studies are required to confirm our findings in a larger number of subjects.

Relationship between Dietary Mercury Intake and Blood Mercury Level in Korea

This study was performed to evaluate the effect of dietary factors for mercury exposure by comparing with blood mercury concentration. Study population consisted of 1,866 adults (839 men and 1,027 women) in randomly-selected 30 districts in southeast Korea. Dietary mercury intake was calculated from food frequency questionnaire (FFQ) on seafood items and 24 hr recall record. Blood mercury concentration was measured with atomic absorption spectrometry. Mean age of the subjects was 43.5 ± 14.6 yr. The FFQ showed that mercury-laden fish (tuna, shark) and frequently-eating fish (squid, belt fish, mackerel) were important in mercury intake from fish species. The recall record suggested that fish and shellfish was a highest group (63.1%) of mercury intake and had a wide distribution in the food groups. In comparison with the blood mercury concentration, age group, sex, household income, education, drinking status and coastal area were statistically significant (P < 0.001). In multiple regression analysis, coefficient from the FFQ (β = 0.003) had greater effect on the blood mercury than the recall record (β = 0.002), but the effect was restricted (adjusted R2 = 0.234). Further studies with more precise estimation of dietary mercury intake were required to evaluate the risk for mercury exposure by foods and assure risk communication with heavily-exposed group. Graphical Abstract

Prevalence of hepatitis B and C virus infection among adults in Korea

Abstract To compare the prevalences of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection in three populations (urban, island, and rural areas), a seroepidemiologic study of HBV and HCV was conducted in Korea, where an HBV is endemic. The study population comprised 1733 adults at least 20 years of age: 532 (male 459, female 73) health examinees (Korean Medical Insurance Corporation [KMIC] beneficiaries) were from Pusan City (urban); 646 (male 531, female 115) health examinees (KMIC beneficiaries) were from Cheju Island (island); and 555 (male 247, female 308) volunteers were from Haman, a rural area in Kyongsangnam Province (rural). A structured questionnaire was completed for each individual by trained interviewers at the time of the health survey of the rural population. A self-administered questionnaire was completed by the health examinees in the urban and island populations. The prevalence of HBsAg in the three populations (age- and sex standardized) was 5.1% in the urban, 6.9% in the island, and 6.1% in the rural populations. These values were not significantly different from each other or from the national population. In contrast, the prevalence of anti-HCV in the rural population (age- and sex-standardized) was 5.4%. This value was higher than that of the urban (0.8%) and island (0.6%) rates. A history of transfusion was not associated with the HCV infection. This study suggests that the rural area is highly endemic for HCV infection and the route of HCV infection is other than blood transfusion in Korea.

Blood Cadmium Concentration of Residents Living near Abandoned Metal Mines in Korea

The purpose of this study was to investigate demographic and lifestyle variables and blood cadmium concentrations in residents living near abandoned metal mines in Korea. Blood cadmium concentrations were measured in 15,161 subjects living around abandoned metal mines (exposed group, n = 14,464) and compared with those living in designated control areas (control group, n = 697). A questionnaire was provided to all subjects to determine age, gender, mine working history, times of residence, smoking habits and dietary water type. The geometric mean (95% confidence intervals) of blood cadmium concentration (1.25 [1.24-1.27] µg/L) in the exposed group was significantly higher than in the control group (1.17 [1.13-1.22] µg/L). Mean residence time and mine working history in the exposed group were significantly higher than in the control group. Blood cadmium concentrations increased with increasing age, and residence time in both groups, and blood cadmium concentrations were higher in current-smokers than in non-smokers in both groups. This study shows the geometric mean of blood cadmium concentration in abandoned mining areas are higher than in non-mining areas in the general adult Korean population. Graphical Abstract

Sexual activity and hepatitis B and C virus infection among young adults after introduction of a vaccination program in an area of high endemicity.

Background In areas where hepatitis is endemic, little is known about the sexual transmission of HBV after introduction of an HBV vaccination program. Methods We used a self-administered questionnaire and serological tests for HBsAg, anti-HBs, anti-HBc, and anti-HCV to examine the role of sexual activity, as well as sociodemographic status, lifestyle habits, and a history of vaccinations, transfusions, and surgery, in the transmission of HBV and HCV in Korea. The subjects were 865 female and 541 male university students (median age, 19 years; age range, 16–25). Results Overall seropositivity was 8.1% for HBsAg, 69.3% for anti-HBs, 21.3% for anti-HBc, and 0.4% for anti-HCV. Regarding HBV, 8% of the subjects were chronic carriers or had recently been infected, 22.8% were never exposed and nonvaccinated, 16.6% were exposed noncarriers, and 52.7% had most likely been vaccinated. We found a significant association between HBsAg seropositivity and history of sexual intercourse (Odds Ratio, 1.8; 95% CI, 1.1–2.8). Students without serologic evidence of immunization against HBV were more likely to have become HBsAg-positive after becoming sexually active. Conclusions Our findings suggest that sexual transmission does occur among adolescents and young adults who have not been vaccinated, whereas vaccination protects individuals from becoming an HBV carrier after becoming sexually active.