title: Do genetic factors contribute to the relation between education and metabolic risk factors in young adults? A twin study.
abstract: BACKGROUND
  Lower educated people have a higher prevalence of metabolic risk factors (MRF), that is, high waist circumference (WC), high systolic blood pressure, low high-density lipoprotein cholesterol level, high triglycerides and high fasting glucose levels. Behavioural and psychosocial factors cannot fully explain this educational gradient. We aim to examine the possible role of genetic factors by estimating the extent to which education and MRF share a genetic basis and the extent to which the heritability of MRF varies across educational levels.
  
  
  METHODS
  We examined 388 twin pairs, aged 18-34 years, from the Belgian East Flanders Prospective Twin Survey. Using structural equation modelling, a Cholesky bivariate model was applied to assess the shared genetic basis between education and MRF. The heritability of MRF across education levels was estimated using a non-linear multivariate Gaussian regression.
  
  
  RESULTS
  Fifteen percent (P < 0.01) of the negative relation between education and WC was because of genes shared between these two traits. Furthermore, the heritability of WC was lower in the lowest educated group (65%) compared with the highest educated group (78%, P = 0.04). The lower heritabilities among the lower educated twins for the other MRF were not significant. The heritability of glucose was higher in the lowest education (80%) group compared with the high education group (67%, P = 0.01).
  
  
  CONCLUSIONS
  Our findings suggest that genetic factors partly explain educational differences in WC. Furthermore, the lower heritability estimates in WC in the lower educated young adults suggest opportunities for environmental interventions to prevent the development of full-blown metabolic syndrome in middle and older age.
authors.affiliation: 1 Department of Social Medicine, CAPHRI, Maastricht University, 6200 MD Maastricht, The Netherlands.
authors.forename: Angelique P A
authors.initials: AP
authors.lastname: Vermeiren
authors.forename: Hans
authors.initials: H
authors.lastname: Bosma
authors.forename: Marij
authors.initials: M
authors.lastname: Gielen
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Lindsey
authors.forename: Catherine
authors.initials: C
authors.lastname: Derom
authors.forename: Robert
authors.initials: R
authors.lastname: Vlietinck
authors.forename: Ruth J F
authors.initials: RJ
authors.lastname: Loos
authors.forename: Maurice P
authors.initials: MP
authors.lastname: Zeegers
mesh_terms: D000293:Adolescent; D000328:Adult; D001530:Belgium / Q000453:epidemiology; D001786:Blood Glucose / Q000032:analysis / Q000235:genetics; D001794:Blood Pressure / Q000235:genetics; D008076:Cholesterol, HDL / Q000097:blood / Q000235:genetics; D004200:Diseases in Twins / Q000453:epidemiology / Q000209:etiology / Q000235:genetics; D004522:Educational Status; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D016014:Linear Models; D008297:Male; D024821:Metabolic Syndrome / Q000453:epidemiology / Q000209:etiology / Q000235:genetics*; D011446:Prospective Studies; D012307:Risk Factors; D014280:Triglycerides / Q000097:blood / Q000235:genetics; D014429:Twins, Dizygotic / Q000235:genetics / Q000706:statistics & numerical data; D014430:Twins, Monozygotic / Q000235:genetics / Q000706:statistics & numerical data; D055105:Waist Circumference / Q000235:genetics; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D008076:Cholesterol, HDL; D014280:Triglycerides