The relationship between bone mineral density and mammographic density in Korean women: the Healthy Twin study.

Sung, Joohon,Song, Yun-Mi,Stone, Jennifer,Lee, Kayoung M. Nijhoff ; Kluwer Academic Publishers 2011 Breast cancer research and treatment Vol.129 No.2

<P>Mammographic density is one of the strong risk factors for breast cancer. A potential mechanism for this association is that cumulative exposure to mammographic density may reflect cumulative exposure to hormones that stimulate cell division in breast stroma and epithelium, which may have corresponding effects on breast cancer development. Bone mineral density (BMD), a marker of lifetime estrogen exposure, has been found to be associated with breast cancer. We examined the association between BMD and mammographic density in a Korean population. Study subjects were 730??Korean women selected from the Healthy Twin study. BMD (g/cm(2)) was measured with dual-energy X-ray absorptiometry. Mammographic density was measured from digital mammograms using a computer-assisted thresholding method. Linear mixed model considering familial correlations and a wide range of covariates was used for analyses. Quantitative genetic analysis was completed using SOLAR. In premenopausal women, positive associations existed between absolute dense area and BMD at ribs, pelvis, and legs, and between percent dense area and BMD at pelvis and legs. However, in postmenopausal women, there was no association between BMD at any site and mammographic density measures. An evaluation of additive genetic cross-trait correlation showed that absolute dense area had a weak-positive additive genetic cross-trait correlation with BMD at ribs and spines after full adjustment of covariates. This finding suggests that the association between mammographic density and breast cancer could, at least in part, be attributable to an estrogen-related hormonal mechanism.</P>

Relationships between state and trait anxiety inventory and alcohol use disorder identification test scores among korean twins and families: the healthy twin study.

Sung, Joohon,Lee, Kayoung,Song, Yun-Mi,Kim, Ji-Hae Published for the ISTS by Australian Academic Pres 2011 TWIN RESEARCH AND HUMAN GENETICS - Vol.14 No.1

<P>We explored heritabilities of the State and Trait Anxiety Inventory (STAI) and the Alcohol Use Disorders Identification Test (AUDIT), and associations including genetic and environmental correlations between the phenotypes among Korean twins and their families. We analyzed the data of 1,748 participants (835 men, 913 women, 656 individuals of monozygotic twins, 173 individuals of same-sexed dizygotic twins, 919 non-twin family members, age 30-79 years) from the Healthy Twin study. Heritabilities and bivariate analyses were assessed using the SOLAR package software. In the methods of generalized estimation equations, women in the 4th quartile of state and trait scores were 17% and 15%, respectively more likely to be hazardous alcohol users compared to women in the lower three quartiles (P < .05). However, there were no significant associations between these phenotypes in men. After adjusting for age and squared age, the heritability estimates were 0.26 in men and 0.34 in women for the state score; for the trait score, 0.35 in men and 0.31 in women; for the AUDIT score, 0.32 in men and 0.37 in women (P < .001). After adjusting for age and squared age, there was a significant genetic correlation between the trait score and the AUDIT score, and a significant non-genetic correlation between the state score and the AUDIT score in women, while there were no significant genetic or non-genetic correlations between these phenotypes in men. The STAI and AUDIT scores are heritable in Koreans and the relationships between these phenotypes may be inconsistent by sex.</P>

Reproductive factors associated with mammographic density: a Korean co-twin control study

Sung, Joohon,Song, Yun-Mi,Stone, Jennifer,Lee, Kayoung,Lee, Donghun Springer-Verlag 2011 Breast cancer research and treatment Vol.128 No.2

Heritabilities of the Metabolic Syndrome Phenotypes and Related Factors in Korean Twins

Sung, Joohon,Lee, Kayoung,Song, Yun-Mi The Endocrine Society 2009 The Journal of clinical endocrinology & metabolism Vol.94 No.12

The relationship between education level and mammographic density

Sung, Joohon,Song, Yun-Mi Lippincott Williams & Wilkins 2015 EUROPEAN JOURNAL OF CANCER PREVENTION Vol.24 No.6

To further understand the factors that contribute to interindividual variation in mammographic density, we evaluated the relationship between education level and each component of the mammographic density measures. Study participants included 535 women between 40 and 65 years of age who received a mammogram for a population-based twin and family study. Mammographic density was measured from digital mammograms using a computer-assisted thresholding method. To avoid negative confounding by obesity level, we calculated BMI-adjusted mammographic measures. Thereafter, each of the mammographic density measures was t-transformed using its mean value and SD for each age strata. The level of education was chosen as a marker representing socioeconomic status at the individual level. A linear mixed model considering familial correlations was used for analyses. In the unadjusted analysis for all women, the BMI-adjusted nondense area gradually decreased with an increase in education level (P for trend=0.017). This association persisted after adjusting for menstrual and reproductive factors. When we repeated the analysis according to menopausal status, an inverse association between education level and nondense area was evident in premenopausal women, whereas the inverse association attenuated to a statistically insignificant level after adjusting for menstrual and reproductive factors in postmenopausal women. Absolute dense area and percentage dense area were not associated with education level. The significant association between nondense area and education level after eliminating the effect of age and BMI suggests that socioeconomic factors may have an influential role in determining the amount of fat tissue in the breast.

Genetic effects on serum testosterone and sex hormone-binding globulin in men: a Korean twin and family study

Sung, Joohon,Song, Yun-Mi Medknow PublicationsMedia Pvt Ltd 2016 ASIAN JOURNAL OF ANDROLOGY Vol.18 No.5

<P>We conducted a community-based cross-sectional study to evaluate the role of genetics in determining the individual difference in total testosterone and sex hormone-binding globulin levels. Study participants comprised 730 Korean men consisting of 142 pairs of monozygotic twins, 191 pairs of siblings, and 259 father-offspring pairs from 270 families who participated in the Healthy Twin study. Serum concentration of total testosterone and sex hormone-binding globulin were measured by chemiluminescence immunoassay, and free testosterone and bioavailable testosterone were calculated using Vermeulen's method. Quantitative genetic analysis based on a variance decomposition model showed that the heritability of total testosterone, free testosterone, bioavailable testosterone, and sex hormone-binding globulin were 0.56, 0.45, 0.44, and 0.69, respectively after accounting for age and body mass index. Proportions of variance explained by age and body mass index varied across different traits, from 8% for total testosterone to 31% for sex hormone-binding globulin. Bivariate analysis showed a high degree of additive genetic correlation (<I>ρ</I><SUB>G</SUB> = 0.67) and a moderate degree of individual-specific environmental correlation (<I>ρ</I><SUB>E</SUB> = 0.42) between total testosterone and sex hormone-binding globulin. The findings confirmed the important role of genetics in determining the individually different levels of testosterone and sex hormone-binding globulin during adulthood in Korean men as found in non-Asian populations, which may suggest that common biologic control for determining testosterone level directly or indirectly through binding protein are largely shared among different populations.</P>

Inbreeding Coefficients in Two Isolated Mongolian Populations - GENDISCAN Study

Joohon Sung,이미경,서정선 한국유전체학회 2008 Genomics & informatics Vol.6 No.1

GENDISCAN study (Gene Discovery for Complex traits in Asian population of Northeast area) was designed to incorporate methodologies which enhance the power to identify genetic variations underlying complex disorders. Use of population isolates as the target population is a unique feather of this study. However, population isolates may have hidden inbreeding structures which can affect the validity of the study. To understand how this issue may affect results of GENDISCAN, we estimated inbreeding coefficients in two study populations in Mongolia. We analyzed the status of Hardy-Weinberg Equilibrium (HWE), polymorphism information contents (PIC), heterozygosity, allelic diversity, and inbreeding coefficients, using 317 and 1,044 STR (short tandem repeat) markers in Orkhontuul and Dashbalbar populations. HWE assumptions were generally met in most markers (88.6% and 94.2% respectively), and single marker PIC ranged between 0.2 and 0.9. Inbreeding coefficients were estimated to be 0.0023 and 0.0021, which are small enough to assure that conventional genetic analysis would work without any specific modification. We concluded that the population isolates used in GENDISCAN study would not present significant inflation of type I errors from inbreeding effects in its gene discovery analysis.

Fasting Blood Glucose and the Risk of Stroke and Myocardial Infarction

Sung, Joohon,Song, Yun-Mi,Ebrahim, Shah,Lawlor, Debbie A. Ovid Technologies Wolters Kluwer -American Heart A 2009 CIRCULATION - Vol.119 No.6

<P>Although diabetes is a well-known risk factor of atherosclerotic cardiovascular diseases, the cardiovascular disease risk of glycemia below the current diabetic threshold remains uncertain.</P>

생활화학물질의 건강영향평가 방안 제언

성주헌(Joohon Sung) 서울대학교 보건환경연구소 2017 보건학논집 Vol.54 No.2

Heritability of Facial Skeletal and Dental Characteristics of Monozygotic and Dizygotic Twins Using Cephalometric Analysis and Falconer’s Method

Kim, Eungmin,Sung, Joohon,Song, Yun-Mi,Chae, Hwa Sung,Mo, Sung-Seo,Kim, Young Ho,Baek, Seung-Hak by Mutaz B. Habal, MD. 2018 JOURNAL OF CRANIOFACIAL SURGERY - Vol.29 No.3

ABSTRACT: The purpose of this study was to investigate the heritability of facial skeletal and dental characteristics of the monozygotic (MZ) and dizygotic (DZ) twins. The samples consisted of Korean MZ and DZ twins (n = 13 pairs/each twin; 7 pairs of males and 6 pairs of females; mean age, 39 years, respectively). The linear, angular, and ratio variables, which could describe the size and shape of the facial horizontal and vertical, dental, mandible and cranial base structure, were measured. The Falconer’s method was used to calculate the heritability (h; close to or below 0, low heritability; close to or above 1, high heritability). In the facial horizontal and vertical aspects, the highest h values were shown at SNA (degree, 1.53), SNB (degree, 2.12), SN-Pog (degree, 2.19), SN-palatal plane angle (degree, 1.29), SN-mandibular plane angle (degree, 1.59), N-ANS/ANS-Me (1.66), and ANS-Me/N-Me (1.62). In the dental aspects, although L1-occlusal plane angle (degree, 1.38) and SN-occlusal plane angle (degree, 2.09) showed high h values, most of the dental variables showed low h values. In the mandible and cranial base, lower gonial angle, mandibular body length, and cranial base angle showed high h values (N-Go-Gn [degree], 1.07; Go-Pog [mm], 0.92; N-S-Ba [degree], 1.51). The descending order of the overall mean h values was the facial horizontal (1.10), facial vertical (0.71), mandible (0.59), cranial base (0.37), and dental characteristics (−0.11). The shape of facial skeletal structure and location of the occlusal plane within skeletal framework was more influenced by genetic factors than environmental factors.