Genetic influences on mammographic density in Korean twin and family: the Healthy Twin study

Abstract

Higher mammographic density is a strong risk factor for breast cancer. This study was conducted to determine the role of genetic factors on mammographic density measurements in Korean women. Study subjects were 730 women (122 monozygotic (MZ) twin pairs, 28 dizygotic (DZ) twin pairs, and 430 first degree relatives) from the Healthy Twin study. Mammographic density was measured using a computer-assisted method. Pairwise correlations of residual variance of each component of mammographic density were calculated within each pair of twins and family members. Quantitative genetic analysis was completed using SOLAR. Age and measured covariates accounted for 50% of the variation in dense area, 70% of non-dense area, and 67% of percent dense area. Fully adjusted heritability coefficients for dense area, non-dense area, and percent dense area were 0.76 (SE = 0.04), 0.69 (SE = 0.04) and 0.68 (SE = 0.04), respectively. Pairwise correlation coefficients of the adjusted residual variance of the mammographic density measures within MZ pairs and within DZ and sibling pairs combined were, respectively, 0.70 and 0.28 for dense area, 0.52 and 0.31 for non-dense area, and 0.58 and 0.24 for percent dense area. Covariance between dense and non-dense area had a significant genetic basis (correlation coefficient = -0.25, SE = 0.06). The same high heritability of mammographic density in Korean women as found in Western women supports a significant role of genetic determinants in breast cancer development. Genes that are responsible for familial correlation in mammographic density and have opposite effects on dense and non-dense mammographic areas need to be elucidated.

A fruit, milk and whole grain dietary pattern is positively associated with bone mineral density in Korean healthy adults

“…30 The coefficient of variation for the BMD measurements based on reproducibility scans was ⩾ 1.0%. 31 The 'low BMD group' was defined as subjects with a T-score of − 1.0 or less in measurements of the whole pelvis or lumbar spine when the maximum BMD value for Asian (Japanese) populations aged ⩾ 20 years was used as a reference. 32 Body weight (kg) was measured using a digital scale to the nearest 0.1 kg with the participant in light clothing and wearing no shoes.…”

The relationship between education level and mammographic density

“…However, it is not completely understood what determines the interindividual variation. Although ethnicity and genetic factors seem to explain a large proportion of the variance in age-adjusted mammographic density (Maskarinec et al, 2007;Boyd et al, 2009;Sung et al, 2010a), nongenetic factors including the use of estrogen replacement therapy, reproductive factors, and body size were also found to contribute to the variance (Santen, 2005;Stone et al, 2009;Sung et al, 2010bSung et al, , 2011.…”

The Heritability of Mammographic Breast Density and Circulating Sex-Hormone Levels: Two Independent Breast Cancer Risk Factors

“…Twin studies estimate that between 50% and 70% of the variance of percentage mammographic density is genetically determined (14)(15)(16)(17). A recent study used a polygenic risk score approach to show that percentage mammographic density and breast cancer have a shared genetic basis that is mediated through a large number of common variants (18).…”