Jin-Su Choi

Relative contribution of body composition to bone mineral density at different sites in men and women of South Korea

We examined the relative contribution of body composition to bone mineral density (BMD) at various sites in 1406 Korean rural men and women, aged 19–80 years, from July to August 2004. The BMD was measured at peripheral (distal forearm and calcaneus) and central (lumbar spine at L1–L4, femoral neck, trochanter, and Wards triangle) using dual-energy X-ray absorptiometry. In multivariate analyses, the linear regression models were adjusted for relevant covariates. In premenopausal women, only lean mass had a significant positive correlation with BMD at all sites. In postmenopausal women, fat mass was significantly positively correlated with BMD at all sites, except the Wards triangle; fat mass was the only determinant of BMD at the lumbar, distal forearm, and calcaneus sites, whereas both lean and fat mass contributed to BMD at the hip, with the effect of lean mass being slightly greater than that of fat mass. In younger men, lean mass had a significant positive contribution to BMD at all sites, whereas fat mass appeared to contribute negatively to BMD at all sites, except the calcaneus. In older men, lean mass made a significant positive contribution to the BMD at all sites; fat mass also made a significant positive contribution to the BMD at the forearm and calcaneus. These data indicate that in the Korean rural population, lean mass may be an important determinant of the BMD, whereas fat mass may contribute positively to BMD only in postmenopausal women and older men.

Association between folate-metabolizing pathway polymorphism and non-Hodgkin lymphoma

Polymorphisms in the genes coding folate‐metabolizing enzymes affect the risk of some forms of cancer. We investigated the association between these polymorphisms and non‐Hodgkin lymphoma (NHL) risk in a population‐based study (583 cases and 1700 controls). The MTHFR 677TT and CT genotypes were associated with reduced risk for NHL [odds ratios (OR) = 0·79; 95% confidence intervals (CI) = 0·65–0·98 for 677CT and 0·61; 0·45–0·82 for 677TT] and diffuse large B‐cell lymphoma (DLBCL) (OR = 0·68; 0·51–0·88 for 677CT; OR = 0·56; 0·38–0·83 for 677TT). The MTHFR 1298CC genotype was associated with increased risk for NHL (OR = 1·71; 1·07–2·75) and T‐cell lymphoma (OR = 3·05; 1·53‐6·11). The MTRR 66GG genotype was associated with increased risk for DLBCL (OR = 1·56; 1·03‐2·38) and the TYMS 2R2R genotype was associated with increased risk for T‐cell lymphoma (OR = 2·83; 1·33–6·01). Using subjects with 3RG3RG as a reference group, TYMS 2R2R was associated with increased risk for T‐cell lymphoma (OR = 2·46; 1·04–5·79). Interestingly, we observed a reduced association between the TYMS 2R3RG genotype and DLBCL (OR = 0·61; 0·38–0·99). These results suggest that MTHFR, MTRR and TYMS polymorphisms may play a significant role in the risk for NHL.

Association between polymorphisms of folate-metabolizing enzymes and hematological malignancies

Several genetic polymorphisms in the genes coding folate-metabolizing enzymes have been associated with susceptibility to hematology malignancies. We conducted a Korean population-based case-control study to examine the relationship between the polymorphisms of folate-metabolizing enzymes and the risk of AML (acute myelogenous leukemia), CML (chronic myelogenous leukemia), MDS (myelodyspastic syndrome), and ALL (acute lymphoblastc leukemia). The MTHFR 677TT genotype was associated with an increased risk for ALL (odds ratios (OR)=1.77; 95% confidence intervals (CI)=1.02-3.09, p=.044). The MTRR 66 AG genotype was associated with an increased risk for MDS (OR=1.59; 1.06-2.38, p=.026) and the MTRR 66 GG genotype was associated with increased risk for AML (OR=1.51; 1.03-2.23, p=.037). The TYMS 2R3R genotype was associated with a decreased risk for AML (OR=0.76; 0.60-0.96, p=.022). The TYMS hap3 (2R-6bp) and hap4 (2R-0bp) were associated with decreased risk (OR=0.69; 0.53-0.90, p=.006) and increased risk (OR=1.65; 1.20-2.27, p=.002), respectively for AML. Hap C (677T-1298A) was associated with an increased risk (OR=1.40; 1.02-1.92, p=.04) for ALL. The risk for ALL appears to be associated with the MTHFR 677 polymorphism. The results are supportive of a risk modification by folate polymorphisms in several hematologic malignancies in Korea. The pattern of results suggests that MDS was associated with the DNA methylation status and the risk for AML was associated with both the DNA synthesis and DNA methylation status.

Rapid increase of scrub typhus, South Korea, 2001-2006.

To the Editor: Scrub typhus, or tsutsugamushi disease, is a febrile illness caused by the rickettsial bacteria Orientia tsutsugamushi. Scrub typhus is endemic to a geographically distinct region, the so-called tsutsugamushi triangle, which includes Japan, Taiwan, China, and South Korea (1,2). Scrub typhus is a public health issue in Asia, where 1 billion persons may be at risk for the disease (3). In South Korea, scrub typhus is the most common rickettsial disease, and public health authorities are concerned about its increased incidence. Scrub typhus has been a reportable disease in South Korea since 1994. Physicians who diagnose suspected or confirmed cases must report these cases to their local health bureau and the Korea Centers for Disease Control and Prevention (KCDC) through the National Notifiable Disease Surveillance System (NNDSS). For a patient’s illness to meet the case definition for scrub typhus, the clinical signs (acute febrile illness and skin eschar) must be present or there must be laboratory confirmation (4-fold rise in antibody titer, antigen detected in blood, or genetic material detected by PCR). We analyzed NNDSS data confirmed by KCDC and classified all reported cases into 2 groups according to residential area. Cases with rural administrative address codes “eup” or “myun” were defined as rural cases, whereas cases with a city administrative address code of “dong” were defined as urban cases. All case-patients were classified by occupation as farmer or nonfarmer; all agricultural, fishery, and forest workers from rural areas were defined as farmers. In total, 23,929 cases, including 16,199 (67.7%) serologically confirmed cases, were reported between 2001 and 2006, of which 35.5% were male patients and 64.5% female patients. The greatest number of cases was in the age group 50–69 years, in both male (47.2%) and female (51.7%) patients; however, there were 167 boys (2.0%) and 119 girls (0.8%) <10 years of age. The number of cases peaked in 2005, with 2,331 and 4,449 cases in male and female patients, respectively. In 2006, a total of 6,480 cases (2,364 and 4,116 in males and females patients), which is 2.5× the number reported in 2001, were reported. The autumn epidemic period was from October through November; 96.2% of all cases were reported during this period (Figure). The proportion of cases identified in farmers decreased from 2001 (44.4%) to 2006 (36.4%); the number of cases in nonfarmers reached 4,121 (63.6%) in 2006. The number and proportion of patients living in urban areas increased from 1,059 (40.2%) in 2001 to 3,230 (49.9%) in 2006. This trend was observed in both farmers and nonfarmers. The number of cases among farmers living in urban areas increased from 150 (12.8%) to 443 (18.8%), while the corresponding number of cases in nonfarmers went from 909 (62.0%) to 2,787 (67.6%). In addition, we identified different features of scrub typhus epidemicity, compared with those reported in previous studies (4–7). Many of the values reported in this study (64.5% of cases in female patients, 59.5% in nonfarmers, and 96.2% occurring in autumn) are higher than the values reported previously in Japan (4), Taiwan (5), and China (6). The higher incidence in female workers may be associated with conventional South Korean working behavior. Female workers typically work in a squatting position, with bare hands, and usually in dry fields, whereas male workers tend to work in a standing position, with tools, and in rice fields. Therefore, female workers are more likely to be exposed to infected mites. Figure Monthly occurrence of scrub typhus cases in South Korea, 2001–2006. Previously, farmers were considered a high-risk group, but our results imply that the same or even more attention should be given to nonfarmers. Leptotrombidium pallidum, a common mite in Korea, first appears in September. Its population then peaks in October and November and to a lesser degree in April and May (7). In autumn, especially around Chusok (Korean Thanksgiving), nonfarmers and urban residents also take part in agricultural activities, such as the chestnut harvest, mowing around graves, and assisting their farmer relatives. A sharp peak in the number of cases occurred during October–November, which is inconsistent with a previous report on vector density showing a secondary peak during April–May (7). This finding suggests that many cases are misreported, especially in spring. Unfortunately, there are still no reports on the comprehensiveness of the scrub typhus surveillance system in South Korea. We cannot exclude other modes of exposure such as golf, climbing, and other outdoor leisure activities. A 5-day work week was introduced in 2004, and, as a result, more leisure time has been available to urban residents. In addition, improved surveillance and diagnostic methods as well as changes in atmospheric temperature (8) may have contributed to the increase. We report the rapid increase of scrub typhus and the proportion of infected persons living in urban areas in South Korea. This information will be used to establish strategies for prevention, surveillance, and management in South Korea and in other countries where scrub typhus is endemic.

Cohort Profile: The Namwon Study and the Dong-gu Study

These two cohorts were designed to examine the increasing burden of chronic diseases among Korean populations. The studies investigated determinants for stroke, osteoporosis, dementia and cancer among middle-aged and elderly Korean populations. The Namwon Study baseline survey was performed between 2004 and 2007 (n = 10 667), and followed up 4 years later (n = 8157, follow-up rate = 76.5%). The baseline survey of the Dong-gu Study was administered over 2007-2010 (n = 9260), and will be followed up between 2014 and 2015. Questionnaires included assessment of cognitive function, psychiatric health and lifestyle factors. Clinical examinations, biochemical tests and genotyping focused on evaluating the determinants of target diseases and their intermediate phenotypes. Potential collaborators will be invited to contact the chief investigators.

Methylenetetrahydrofolate reductase C677T polymorphism in patients with gastric and colorectal cancer in a Korean population

BackgroundThis study was designed to investigate an association between the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and the risk of gastric and colorectal cancer in the Korean population.MethodsWe conducted a population-based large-scale case-control study involving 2,213 patients with newly diagnosed gastric cancer, 1,829 patients with newly diagnosed colorectal cancer, and 1,700 healthy controls. Genotyping was performed with peripheral blood DNA for MTHFR C677T polymorphisms. The statistical significance was estimated by logistic regression analysis.ResultsThe MTHFR C677T frequencies of CC, CT, and TT genotypes were 35.2%, 47.5%, and 17.3% among stomach cancer, 34%, 50.5%, and 15.5% in colorectal cancer, and 31.8%, 50.7%, and 17.5% in the controls, respectively. The MTHFR 677TT genotype showed a weak opposite association with colorectal cancer compared to the homozygous CC genotype [adjusted age and sex odds ratio (OR) = 0.792, 95% confidence interval (CI) = 0.638-0.984, P = 0.035]. Subjects with the MTHFR 677CT showed a significantly reduced risk of gastric cancer compared whose with the 677CC genotype (age- and sex-adjusted OR = 0.810; 95% CI = 0.696-0.942, P = 0.006). We also observed no significant interactions between the MTHFR C677T polymorphism and smoking or drinking in the risk of gastric and colorectal cancer.ConclusionsThe T allele was found to provide a weak protective association with gastric cancer and colorectal cancer.

Prevalence of osteoporosis and reference data for lumbar spine and hip bone mineral density in a Korean population

The aims of this study were to establish reference data for bone mineral density (BMD) at central skeletal sites using Lunar dual-energy X-ray absorptiometry (DXA), and to estimate the age-and sex-specific prevalence of osteoporosis in a Korean population. We performed a population-based, cross-sectional study. The subjects were 4148 (1810 men and 2338 women) Korean adults, aged 20–79 years. The BMD for central sites (lumbar spine, femoral neck, trochanter, and Ward’s triangle) were measured by DXA. The standardized prevalence of osteoporosis among individual aged 50–79 years in lumbar spine, femoral neck, Ward’s triangle, and trochanter was 40.1%, 12.4%, 28.4%, and 4.4% in women and 6.5%, 5.9%, 3.7%, and 1.6% in men, respectively. In women, peak BMD occurred in the age range 40–49 years for the femoral neck and trochanter, 30–39 years for the lumbar spine, and 20–29 years for Ward’s triangle. In men, peak BMD values were observed at 20–29 years for all measured sites. This study establishes a normative database for BMD at central skeletal sites using dualenergy X-ray absorptiometry and provides more reliable information on the prevalence of osteoporosis in Korea.

Thyroid Cancer is the Most Common Cancer in Women, Based on the Data from Population-based Cancer Registries, South Korea

Similar to worldwide trends, the incidence of thyroid cancer in South Korea has increased steadily in recent decades. We examined the trends in thyroid cancer incidence in Gwangju and Jeonnam provinces between 1996 and 2010, and identified 19 881 cases (men 3282/16.5%; women 16 599/83.5%) from the Gwangju Cancer Registry and Jeonnam Cancer Registry databases, which are population-based cancer registries. Age-standardized incidence rates per 100 000 persons, using hypothetical world standard population (Segi), increased from 1.9 in 1996 to 27.0 in 2010 in men, and from 10.6 to 111.3 in women, respectively. The estimated annual percentage changes (95% confidence interval) of age-standardized incidence rates were 27.1% (24.6-29.6) and 19.7% (16.4-23.2) for men and women, respectively, during the same period. The proportion of papillary-type thyroid cancer increased from 74.2 and 75.4% in 1996 to 97.9 and 98.3% in 2010 for men and women, respectively. We found the most prominent increasing trends and the highest incidence rate of thyroid cancer among those that have ever been reported. Thyroid cancer has been the leading cancer in women since 2003 and is now the fifth most common cancer in men in Gwangju and Jeonnam, South Korea.

Association between hemoglobin A1c, carotid atherosclerosis, arterial stiffness, and peripheral arterial disease in Korean type 2 diabetic patients.

AIMS To evaluate the association between hemoglobin A(1c) (HbA(1c)), carotid atherosclerosis, arterial stiffness, and peripheral arterial disease (PAD) in Korean type 2 diabetic patients. METHODS A total of 370 type 2 diabetic patients registered with the public health center in Gokseng-gun, Korea, participated in this study. Following an overnight fast, venous blood was collected and analyzed by high-performance liquid chromatography. The carotid intima-media thickness (IMT), amount of carotid plaque, brachial ankle pulse wave velocity (baPWV), and ankle-brachial index (ABI) of each patient were also assessed. RESULTS For categorical variables, we performed logistic regression after adjustment for other CVD risk factors. There was a significant association between HbA(1c) and carotid plaque [OR 2.66, 95% confidence interval (CI) 1.01 to 5.67 for the highest vs. the lowest tertile of HbA(1c)], and PAD (OR 3.75, 95% CI 1.30 to 10.81). For continuous variables, we performed analysis of covariance (ANCOVA) after adjustment for other covariates. The mean values of common carotid artery intima-media thickness (CCA-IMT) and baPWV were not significantly different according to the HbA(1c) tertiles. CONCLUSION HbA(1c) was significantly associated with carotid plaque and PAD, but not CCA-IMT and baPWV in Korean type 2 diabetic patients.

Distribution of the Ankle-Brachial Index and Associated Cardiovascular Risk Factors in a Population of Middle-Aged and Elderly Koreans

The Doppler ankle-brachial pressure index (ABI) is an objective and efficient tool that can be used to determine the presence and severity of peripheral arterial disease in the lower extremities. The ABI value is inversely associated with other cardiovascular risk factors. To date, there have been no studies of the distribution of ABI in Korea. We performed a cross-sectional study of 1,943 subjects (681 men and 1,262 women; 45-74 yr old) in Namwon, Korea. The prevalence of a low ABI (<0.90) was 2.2% in men and 1.8% in women, and a high ABI (≥1.30) was prevalent in 3.1% of men and 0.8% of women. Age, smoking habits, waist circumference, hypertension, and blood pressure were associated with ABI values in both sexes. The presence of carotid plaques was associated with ABI values only in men, whereas pulse pressure was associated with ABI values only in women (p<0.05). Although the prevalence of a low ABI in the present study was lower than those reported previously for Western populations and Japanese men, our results suggest that the ABI might be used as an indicator of cardiovascular risk factors in adult Koreans.