This is a population-based survey conducted by the Radboud University Nijmegen Medical Centre (Wetzels et al. 2007) in Nijmegen, a town in the eastern part of The Netherlands. Age- and sex-stratified randomly selected adult inhabitants received an invitation to fill out a postal questionnaire on lifestyle and medical history. Genotype and phenotype data were available for 1 338 participants (50.5% female), aged 27–78 years (mean=61.5±10.3).
