title: A sibling based design to quantify genetic and shared environmental effects of venous thromboembolism in Sweden.
abstract: BACKGROUND
  Few large studies have examined the heritability of venous thromboembolism (VTE). Moreover, twin studies have been suggested to overestimate heritability. The aim of the present study was to determine the heritability nationwide in the general Swedish population using full siblings and half-siblings.
  
  
  METHODS
  VTE was defined using the Swedish patient register. Full sibling (FS) and half-sibling (HS) pairs born 1950-1990 were obtained from the Swedish Multi-generation Register. A maximum of 5years age difference was allowed. We also required that the individuals within the pair should reside in the same household for at least 8years or not at all (0years) before the youngest turned 16. Information about sibling pair residence within the same household, small residential area, and municipality was obtained from Statistics Sweden. We assumed three potential sources of liability to VTE: additive genetic (A), shared (or common/familial) environment (C), and unique environment (E) components.
  
  
  RESULTS
  Totally 881,206 FS pairs and 95,198 HS pairs were included. The full model predicted heritability for VTE with 47% for males and 40% for females. Environmental factors shared by siblings contributed to 0% of the variance in liability for both sexes, and unique environment (E) components accounted for 53% in males and 60% in females.
  
  
  CONCLUSIONS
  The high heritability of VTE risk indicates that genetic susceptibility plays a substantial role for VTE in the Swedish general population. Overestimation of heritability from twin studies is not likely. The proportion of the variance attributable to shared familial environment factors is small. Subject codes: Genetics, epidemiology, thrombosis, cardiovascular disease, embolism.
authors: Center for Primary Health Care Research, Lund University, Malmö, Sweden. Electronic address: bengt.zoller@med.lu.se.
authors: Bengt
authors: B
authors: Zöller
authors: Center for Primary Health Care Research, Lund University, Malmö, Sweden.
authors: Henrik
authors: H
authors: Ohlsson
authors: Center for Primary Health Care Research, Lund University, Malmö, Sweden.
authors: Jan
authors: J
authors: Sundquist
authors: Center for Primary Health Care Research, Lund University, Malmö, Sweden.
authors: Kristina
authors: K
authors: Sundquist
mesh_terms: D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D012042:Registries; D012307:Risk Factors; D035781:Siblings; D013548:Sweden / Q000453:epidemiology; D054556:Venous Thromboembolism / Q000453:epidemiology* / Q000235:genetics*
keywords: Epidemiological studies; Genetic predisposition to disease; Genetics; Venous thromboembolism; Venous thrombosis