title: The heritability of blood donation: a population-based nationwide twin study.
abstract: BACKGROUND
  Voluntary blood donation is believed to be mostly motivated by altruism. Because studies have suggested that altruistic personality is determined by both genetic and environmental factors, we speculated that willingness to donate blood could also be governed by constitutional factors. This hypothesis was tested in a study among Danish twins.
  
  
  METHODS
  The nationwide Danish Twin Register, which is virtually complete for all twins born since 1968, was linked with Danish portion of the Scandinavian Donation and Transfusion (SCANDAT) Database, which includes information on all active Danish blood donors from 2002 to 2012, to establish blood donor status for Danish twins, who at age 17 years became eligible for donation in 2002 or later. Casewise concordance in monozygotic (MZ) and dizygotic (DZ) twins were presented and heritability was estimated in Mx by variance component analysis in a liability threshold model.
  
  
  RESULTS
  A total of 274 MZ and 484 same-sex DZ twins age 17 to 27 years were identified as donors in SCANDAT. There was no difference between MZ and DZ twins with regard to age at first donation or number of donations. Casewise concordance rates were 0.61 (95% confidence interval [CI], 0.56-0.67) and 0.41 (95% CI, 0.36-0.47) in MZ and DZ twin pairs, respectively. Heritability analysis using the ACE model found that additive genetic and shared environmental effects accounted for 0.53 (95% CI, 0.33-0.73) and 0.28 (95% CI, 0.10-0.45) of the variance in the motivation to donate blood, respectively.
  
  
  CONCLUSIONS
  Becoming a volunteer blood donor is determined by both genetic and environmental factors shared within families.
authors: Department of Clinical Immunology, Naestved Hospital, Naestved, Denmark.
authors: Ole Birger
authors: OB
authors: Pedersen
authors: Danish Twin Registry, University of Southern Denmark, Odense, Denmark.
authors: Skytthe
authors: S
authors: Axel
authors: Department of Epidemiology Research, Statens Serum Institut.
authors: Klaus
authors: K
authors: Rostgaard
authors: Department of Clinical Immunology, Aarhus University Hospital, Aarhus, Denmark.
authors: Christian
authors: C
authors: Erikstrup
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Solna, Sweden.
authors: Gustaf
authors: G
authors: Edgren
authors: Department of Clinical Immunology, Aalborg Hospital, Aalborg, Denmark.
authors: Kaspar René
authors: KR
authors: Nielsen
authors: Department of Clinical Immunology, Copenhagen University Hospital, Copenhagen, Denmark.
authors: Henrik
authors: H
authors: Ullum
authors: Institute of Regional Health Research, University of Southern Denmark and Odense Patient Data Explorative Network (OPEN), Odense University Hospital, Odense, Denmark.
authors: Kirsten Ohm
authors: KO
authors: Kyvik
authors: Department of Epidemiology Research, Statens Serum Institut.
authors: Henrik
authors: H
authors: Hjalgrim
mesh_terms: D000293:Adolescent; D000328:Adult; D001782:Blood Donors; D003718:Denmark; D005260:Female; D006801:Humans; D008297:Male; D008957:Models, Genetic; D012042:Registries; D014429:Twins, Dizygotic / Q000235:genetics*; D014430:Twins, Monozygotic / Q000235:genetics*