Returns to Education: Evidence from UK Twins

We use a new sample of UK female identical twins to estimate private economic returns to education. We report findings in three areas. First, we use identical twins, to control for family effects and genetic ability bias, and the education reported by the other twin to control for schooling measurement error. Our estimates suggest a return to schooling for UK females of about 7.7%. Second, we investigate within-twin pair ability differences by examining within-twin pair and between-family correlations of education with observable correlates of ability (including birthweight, ability tests and reading scores). Our findings suggest lower ability bias in within-twin pair regressions than pooled regressions. Third, using data on twins smoking we show smoking reflects family background and using it as an instrument exacerbates ability bias.Returns to education, Ability bias, Twins, Measurement error, Smoking

Biomarkers in osteoarthritis

Biomarkers aid the study of osteoarthritis (OA) in a number of different ways. In this article we summarise briefly their multiple uses and reflect on how the study reported in a previous edition of Arthritis Research & Therapy should promote further investigation of cartilage oligomeric matrix protein (COMP). COMP is foremost among hitherto investigated biomarkers and is most consistently shown to predict knee OA progression. Precisely what role it plays in OA pathogenesis remains unclear and elucidating this may be key to defining, and then targeting, the cellular pathways involved in OA

Higher dietary flavonoid intakes are associated with lower objectively measured body composition in women: evidence from discordant monozygotic twins

Background: Although dietary flavonoid intake has been associated with less weight gain there are limited data on its impact on fat mass and the contribution of genetic factors to this relationship has not previously been assessed. Objective: To examine associations between flavonoid intakes and fat mass. Design: In a study of 2734 healthy female twins aged 18-83 years from the TwinsUK registry intakes oftotalflavonoids and seven subclasses(flavanones, anthocyanins, flavan-3-ols, flavonols, flavones, polymers and proanthocyanidins) were calculated from food frequency questionnaires. Measures of DXA-derived fat mass included limb-to-trunk fat ratio (FMR), fat mass index and central fat mass index. Results: In cross-sectional multivariable analyses, higher intake of anthocyanins, flavonols and proanthocyanidins were associated with lower FMR, with differences between extreme quintiles of -0.03 (SE 0.02 P-trend = 0.02), -0.03 (SE 0.02 P-trend = 0.03) and -0.05 (SE 0.02 P-trend <0.01), respectively. These associationsremained significant even after further adjustment for fibre and total fruit and vegetable intakes. In monozygotic intake-discordant twin-pairs, those with higher intakes of flavan-3-ols (n= 154, P = 0.03), flavonols (n= 173, P = 0.03) and proanthocyanidins (n= 172, P < 0.01)had significantly lower FMR than their cotwins with within-pair differences of 3-4%. Furthermore, in confirmatory food-based analyses, twins with higher intake of flavonol- (onion, tea and pears, P = 0.01) and proanthocyanidin- (apples and cocoa drinks, P = 0.04) and, in younger participants (< 50 y) only, anthocyanin-rich foods (berries, pears, grapes and wine, P = 0.01) had 3-9% lower FMR than their co-twins. Conclusions: These data suggest that higher habitual intake of a number of flavonoids, including anthocyanins,flavan-3-ols,flavonols and proanthocyanidins, are associated with lower fat massindependent ofshared genetic and common environmental factors. Intervention trials are now needed to further examine the effect of flavonoid-rich foods on body composition

Decreasing initial telomere length in humans intergenerationally understates age-associated telomere shortening

Telomere length shortens with aging, and short telomeres have been linked to a wide variety of pathologies. Previous studies suggested a discrepancy in age-associated telomere shortening rate estimated by cross-sectional studies versus the rate measured in longitudinal studies, indicating a potential bias in cross-sectional estimates. Intergenerational changes in initial telomere length, such as that predicted by the previously described effect of a father's age at birth of his offspring (FAB), could explain the discrepancy in shortening rate measurements. We evaluated whether changes occur in initial telomere length over multiple generations in three large datasets and identified paternal birth year (PBY) as a variable that reconciles the difference between longitudinal and cross-sectional measurements. We also clarify the association between FAB and offspring telomere length, demonstrating that this effect is substantially larger than reported in the past. These results indicate the presence of a downward secular trend in telomere length at birth over generational time with potential public health implications

RELATION OF PULSE WAVE VELOCITY TO CONTEMPORANEOUS AND HISTORICAL BLOOD PRESSURE IN FEMALE TWINS:Arterial Stiffness and Blood Pressure

An association between blood pressure and aortic stiffness is well known, but ambiguity remains as to whether one precedes the other. This study aimed to investigate the association of aortic stiffness with contemporaneous versus historic blood pressure and direction of causality between aortic stiffening and hypertension in female twins. METHODS: Aortic stiffness, measured by carotid-femoral pulse wave velocity (PWV), and mean arterial pressure (MAP) was recorded in 2037 female TwinsUK participants (mean age: 62.4±9.7 years) at a single time point. A subset of 947 participants had repeat PWV and MAP measures (mean interval 5.5±1.7 years) with additional historic MAP (mean interval 6.6±3.3 years before baseline). RESULTS: Cross-sectional multivariable linear regression analysis confirmed PWV significantly associated with age and MAP. In longitudinal analysis, annual progression of PWV was not associated with historic MAP (standardized beta coefficient [β]=-0.02, P=0.698), weakly associated with baseline MAP (β=0.09, P=0.049) but strongly associated with progression (from baseline to most recent measurement) of MAP (β= 0.26, P<0.001). Progression of MAP associated with both baseline and progression of PWV (β=0.13, P=0.003 and β=0.24, P<0.001, respectively). CONCLUSIONS: Progression of aortic stiffness associates more strongly with contemporaneous MAP compared with historic MAP. In contrast, progression of MAP is associated with prior arterial stiffness. These findings suggest a bidirectional relationship between arterial stiffness and blood pressure, and that lowering blood pressure may prevent a cycle of arterial stiffening and hypertension

Affective responses to sweet products and sweet solution in British and Finnish adults

Peer reviewe

Estimating telomere length from whole genome sequence data.

Telomeres play a key role in replicative ageing and undergo age-dependent attrition in vivo. Here, we report a novel method, TelSeq, to measure average telomere length from whole genome or exome shotgun sequence data. In 260 leukocyte samples, we show that TelSeq results correlate with Southern blot measurements of the mean length of terminal restriction fragments (mTRFs) and display age-dependent attrition comparably well as mTRFs

Innate and adaptive immune traits are differentially affected by genetic and environmental factors

The diversity and activity of leukocytes is controlled by genetic and environmental influences to maintain balanced immune responses. However, the relative contribution of environmental compared with genetic factors that affect variations in immune traits is unknown. Here we analyse 23,394 immune phenotypes in 497 adult female twins. 76% of these traits show a predominantly heritable influence, whereas 24% are mostly influenced by environment. These data highlight the importance of shared childhood environmental influences such as diet, infections or microbes in shaping immune homeostasis for monocytes, B1 cells, γδ T cells and NKT cells, whereas dendritic cells, B2 cells, CD4(+) T and CD8(+) T cells are more influenced by genetics. Although leukocyte subsets are influenced by genetics and environment, adaptive immune traits are more affected by genetics, whereas innate immune traits are more affected by environment

A Survey of UK Public Interest in Internet-Based Personal Genome Testing

Background:In view of the increasing availability of commercial internet-based Personal Genome Testing (PGT), this study aimed to explore the reasons why people would consider taking such a test and how they would use the genetic risk information provided. Methodology/Principal Findings: A self-completion questionnaire assessing public awareness and interest in PGT and motivational reasons for undergoing PGT was completed by 4,050 unselected adult volunteers from the UK-based TwinsUK register, aged 17 to 91 (response rate 62%). Only 13% of respondents were aware of the existence of PGT. After reading a brief summary about PGT, one in twenty participants (5%) were potentially interested at current prices (£250), however this proportion rose to half (50%) if the test was free of charge. Nearly all respondents who were interested in free PGT reported they would take the test to encourage them to adopt a healthier lifestyle if found to be at high genetic risk of a disease (93%). Around 4 in 5 respondents would have the test to convey genetic risk information to their children and a similar proportion felt that having a PGT would enable their doctor to monitor their health more closely. A TwinsUK research focus group also indicated that consumers would consult their GP to help interpret results of PGT. Conclusions/Significance: This hypothetical study suggests that increasing publicity and decreasing costs of PGT may lead to increased uptake, driven in part by the general public's desire to monitor and improve their health. Although the future extent of the clinical utility of PGT is currently unknown, it is crucial that consumers are well informed about the current limitations of PGT. Our results suggest that health professionals will inevitably be required to respond to individuals who have undergone PGT. This has implications for health service providers regarding both cost and time