Height, body mass index, and socioeconomic status: mendelian randomisation study in UK Biobank

Abstract

ObjeCtiveTo determine whether height and body mass index (BMI) have a causal role in five measures of socioeconomic status. DesignMendelian randomisation study to test for causal effects of differences in stature and BMI on five measures of socioeconomic status. Mendelian randomisation exploits the fact that genotypes are randomly assigned at conception and thus not confounded by non-genetic factors.PartiCiPants 119 669 men and women of British ancestry, aged between 37 and 73 years. Main OutCOMe MeasuresAge completed full time education, degree level education, job class, annual household income, and Townsend deprivation index. resultsIn the UK Biobank study, shorter stature and higher BMI were observationally associated with several measures of lower socioeconomic status. The associations between shorter stature and lower socioeconomic status tended to be stronger in men, and the associations between higher BMI and lower socioeconomic status tended to be stronger in women. For example, a 1 standard deviation (SD) higher BMI was associated with a £210 (€276; $300; 95% confidence interval £84 to £420; P=6×10 −3 ) lower annual household income in men and a £1890 (£1680 to £2100; P=6×10 −15 ) lower annual household income in women. Genetic analysis provided evidence that these associations were partly causal. A genetically determined 1 SD (6.3 cm) taller stature caused a 0.06 (0.02 to 0.09) year older age of completing full time education (P=0.01), a 1.12 (1.07 to 1.18) times higher odds of working in a skilled profession (P=6×10 −7 ), and a £1130 (£680 to £1580) higher annual household income (P=4×10 −8 ). Associations were stronger in men. A genetically determined 1 SD higher BMI (4.6 kg/m 2 ) caused a £2940 (£1680 to £4200; P=1×10 −5 ) lower annual household income and a 0.10 (0.04 to 0.16) SD (P=0.001) higher level of deprivation in women only. COnClusiOnsThese data support evidence that height and BMI play an important partial role in determining several aspects of a person's socioeconomic status, especially women's BMI for income and deprivation and men's height for education, income, and job class. These findings have important social and health implications, supporting evidence that overweight people, especially women, are at a disadvantage and that taller people, especially men, are at an advantage.

Phenome-wide Heritability Analysis of the UK Biobank

“…Mortality selection can also alter the results of genetic analyses as shown by recent analyses [51]. In addition, the UK Biobank participants comprised a relatively high proportion of well-educated, skilled professionals [52], potentially leading to the underrepresentation or restricted range of certain traits such as smoking relative to other cohorts. Therefore, our heritability estimates may be specific to this UK population and may not generalize to other settings or ancestry groups.…”

Does higher education protect against obesity? Evidence using Mendelian randomization

“…This method uses genetic instruments to estimate causal effects (Tyrrell et al, 2016;Böckerman et al, 2017;Gupta et al, 2017). The method exploits Mendel's law of independent assortment according to which trait is inherited independently from other traits at conception.…”

“…The current study examines the relationship between education and BMI using Mendelian randomization, which is based on the random assignment of genotypes at conception (Tyrrell et al, 2016;Gupta et al, 2017;Davey Smith et al, 2017). This randomization by nature enables the use of a genetic score as an instrument for education and to detect a causal relationship between education and BMI.…”

Body structure and maturation – the association with environmental factors

“…Very interesting results have been obtained from studies on future effect of height and BMI on measures of SES, based on UK Biobank. High BMI plays very important role in women, lowering their income, and taller people are at an advantage (Tyrrell et al 2016).…”