Genetic and environmental relationships between Framingham Risk Score and adiposity measures in Koreans: the Healthy Twin study

Pleiotropy of cardiometabolic syndrome with obesity-related anthropometric traits determined using empirically derived kinships from the Busselton Health Study

Over two billion adults are overweight or obese and therefore at an increased risk of cardiometabolic syndrome (CMS). Obesity-related anthropometric traits genetically correlated with CMS may provide insight into CMS aetiology. The aim of this study was to utilise an empirically derived genetic relatedness matrix to calculate heritabilities and genetic correlations between CMS and anthropometric traits to determine whether they share genetic risk factors (pleiotropy). We used genome-wide single nucleotide polymorphism (SNP) data on 4671 Busselton Health Study participants. Exploiting both known and unknown relatedness, empirical kinship probabilities were estimated using these SNP data. General linear mixed models implemented in SOLAR were used to estimate narrow-sense heritabilities (h ²) and genetic correlations (r _g) between 15 anthropometric and 9 CMS traits. Anthropometric traits were adjusted by body mass index (BMI) to determine whether the observed genetic correlation was independent of obesity. After adjustment for multiple testing, all CMS and anthropometric traits were significantly heritable (h ² range 0.18-0.57). We identified 50 significant genetic correlations (r _g range: - 0.37 to 0.75) between CMS and anthropometric traits. Five genetic correlations remained significant after adjustment for BMI [high density lipoprotein cholesterol (HDL-C) and waist-hip ratio; triglycerides and waist-hip ratio; triglycerides and waist-height ratio; non-HDL-C and waist-height ratio; insulin and iliac skinfold thickness]. This study provides evidence for the presence of potentially pleiotropic genes that affect both anthropometric and CMS traits, independently of obesity.

Association between Lumbar Bone Mineral Density and Carotid Intima-Media Thickness in Korean Adults: a Cross-sectional Study of Healthy Twin Study

Bone mineral density (BMD) has been suggested to be associated with atherosclerosis. In the present study, we evaluated the association between lumbar BMD and the segments of carotid intima-media thickness (CIMT), a surrogate marker of subclinical atherosclerosis, in Korean adults, with consideration of sex and menopause status. Among 1,679 Korean adults who enrolled in a Healthy Twin Study, 723 men, 690 premenopausal women, and 266 postmenopausal women measured the CIMT at the common carotid artery intima-media thickness (CCA-IMT), carotid bifurcation intima-media thickness (BIF-IMT), internal carotid artery intima-media thickness (ICA-IMT) using B-mode ultrasound and lumbar BMD using dual-energy X-ray absorptiometry. The composite CIMT was calculated as the mean value of three CIMTs. The association was evaluated using linear mixed models. In premenopausal women, lumbar BMD was positively associated with composite CIMT and with CCA-IMT (P = 0.008 and 0.002, respectively). However, no association was observed between BMD and CIMT in men or in postmenopausal women. Stratified analysis revealed the effect of body mass index (BMI) on the association between BMD and CIME. The positive association in premenopausal women persisted only in low BMI (< 25 kg/m²) group, whereas a positive association appeared at high BMI (≥ 25 kg/m²) group in men. A high lumbar BMD may indicate an elevated risk of subclinical atherosclerosis in premenopausal women and men with high BMI.

Genome-wide association studies suggest sex-specific loci associated with abdominal and visceral fat

BACKGROUND

To identify loci associated with abdominal fat and replicate prior findings, we performed genome-wide association (GWA) studies of abdominal fat traits: subcutaneous adipose tissue (SAT); visceral adipose tissue (VAT); total adipose tissue (TAT) and visceral to subcutaneous adipose tissue ratio (VSR).

SUBJECTS AND METHODS

Sex-combined and sex-stratified analyses were performed on each trait with (TRAIT-BMI) or without (TRAIT) adjustment for body mass index (BMI), and cohort-specific results were combined via a fixed effects meta-analysis. A total of 2513 subjects of European descent were available for the discovery phase. For replication, 2171 European Americans and 772 African Americans were available.

RESULTS

A total of 52 single-nucleotide polymorphisms (SNPs) encompassing 7 loci showed suggestive evidence of association (P<1.0 × 10(-6)) with abdominal fat in the sex-combined analyses. The strongest evidence was found on chromosome 7p14.3 between a SNP near BBS9 gene and VAT (rs12374818; P=1.10 × 10(-7)), an association that was replicated (P=0.02). For the BMI-adjusted trait, the strongest evidence of association was found between a SNP near CYCSP30 and VAT-BMI (rs10506943; P=2.42 × 10(-7)). Our sex-specific analyses identified one genome-wide significant (P<5.0 × 10(-8)) locus for SAT in women with 11 SNPs encompassing the MLLT10, DNAJC1 and EBLN1 genes on chromosome 10p12.31 (P=3.97 × 10(-8) to 1.13 × 10(-8)). The THNSL2 gene previously associated with VAT in women was also replicated (P=0.006). The six gene/loci showing the strongest evidence of association with VAT or VAT-BMI were interrogated for their functional links with obesity and inflammation using the Biograph knowledge-mining software. Genes showing the closest functional links with obesity and inflammation were ADCY8 and KCNK9, respectively.

CONCLUSIONS

Our results provide evidence for new loci influencing abdominal visceral (BBS9, ADCY8, KCNK9) and subcutaneous (MLLT10/DNAJC1/EBLN1) fat, and confirmed a locus (THNSL2) previously reported to be associated with abdominal fat in women.

Waist:height ratio: a superior index in estimating cardiovascular risks in Turkish adults

OBJECTIVE

To determine the best anthropometric measurement among waist: height ratio (WHtR), BMI, waist:hip ratio (WHR) and waist circumference (WC) associated with high CHD risk in adults and to define the optimal cut-off point for WHtR.

DESIGN

Population-based cross-sectional study.

SETTING

Balcova, Izmir, Turkey.

SUBJECTS

Individuals (n 10 878) who participated in the baseline survey of the Heart of Balcova Project. For each participant, 10-year coronary event risk (Framingham risk score) was calculated using data on age, sex, smoking status, blood pressure, serum lipids and diabetes status. Participants who had risk higher than 10 % were defined as 'medium or high risk'.

RESULTS

Among the participants, 67·7% were female, 38·2% were obese, 24·5% had high blood pressure, 9·2% had diabetes, 1·5% had undiagnosed diabetes (≥126 mg/dl), 22·0% had high total cholesterol and 45·9% had low HDL-cholesterol. According to Framingham risk score, 32·7% of them had a risk score higher than 10 %. Those who had medium or high risk had significantly higher mean BMI, WHtR, WHR and WC compared with those at low risk. According to receiver-operating characteristic curves, WHtR was the best and BMI was the worst indicator of CHD risk for both sexes. For both men and women, 0·55 was the optimal cut-off point for WHtR for CHD risk.

CONCLUSIONS

BMI should not be used alone for evaluating obesity when estimating cardiometabolic risks. WHtR was found to be a successful measurement for determining cardiovascular risks. A cut-off point of '0·5' can be used for categorizing WHtR in order to target people at high CHD risk for preventive actions.

Multiple analytical approaches demonstrate a complex relationship of genetic and nongenetic factors with cisplatin- and carboplatin-induced nephrotoxicity in lung cancer patients

Background. Cisplatin and carboplatin cause nephrotoxicity by forming platinum-DNA adducts and lead to cell death. Methods. One-hundred and sixteen Taiwanese lung cancer patients who received cisplatin or carboplatin more than twice were recruited, and their genotypes were determined. The risk of renal dysfunction, injury to the kidney, failure of kidney function, loss of kidney function, and end-stage kidney disease (RIFLE) criteria were used to evaluate the occurrence of nephrotoxicity. A logistic regression, multiple regression with a classification and regression tree (CART), and the Framingham study risk score were used to analyze interactions between genetic and nongenetic factors in producing platinum-induced nephrotoxicity. Results. ERCC1 118C and TP53 72Arg polymorphisms were associated with increased risks of platinum-induced nephrotoxicity. Other risk factors found included the platinum type, baseline serum creatinine (Scr), coadministration of vinorelbine, and the number of chemotherapy cycles. The overall prediction rate of the CART was 82.7%, with a sensitivity of 0.630 and specificity of 0.896. The Framingham study risk prediction model contained 7 factors. Its prediction rate was 84.5%, with a sensitivity of 0.643 and specificity of 0.909. Conclusions. Genetic polymorphisms of ERCC1 and TP53 are risk factors for nephrotoxicity. The CART analysis may provide a clinically applicable model to predict the risk of cisplatin- and carboplatin-induced nephrotoxicity.

Variation in the heritability of body mass index based on diverse twin studies: a systematic review

OBJECTIVES

Over the past three decades, twin studies have shown variation in the heritability of obesity. This study examined the difference of body mass index (BMI) heritability (BMI-H) by population characteristics, such as sex, age, time period of observation and average BMI, as well as by broad social-environmental factors as indicated by country-level gross domestic product (GDP) per capita and GDP growth rate.

METHODS

Twin studies that reported BMI-H and were published in English from January 1990 to February 2011 after excluding those with disease, special occupations or combined heritability estimates for country/ethnic groups were searched in PubMed. 32 studies were identified from Finland (7), the United Kingdom (6), the United States (3), Denmark (3), China (3), Netherlands (2), South Korea (2), Sweden (2) and four from other countries. Meta-regression models with random effects were used to assess variation in BMI-H.

RESULTS

Heterogeneity of BMI-H is significantly attributable to variations in age (<20, 20-55 and ≥56 years), time period of observation (i.e. year of data collection), average BMI and GDP (≤$20,000, $20,001-26,000 and >$26,000). BMI-H was higher in adolescents (<20 years), in studies done in past years, and in populations with higher average BMIs or higher GDP per capita (≥$26,000) than their counterparts. Consistent lowering effects of high GDP growth rate (>median) on BMI-H were shown through stratified analyses by GDP. BMI-H was lower in countries of mid-level GDP, particularly those experiencing rapid economic growth.

CONCLUSIONS

BMI-H is sensitive to age, time period of observation, average BMI, GDP and rapid economic growth.