GS:SFHS is a family‐based epidemiological cohort recruited at random through general medical practices across Scotland. The protocol for recruitment is described in detail elsewhere (Smith et al. 2006). The cohort consists of 21 516 individuals over 18 years of age recruited if they had at least one other family member willing to participate. Genome‐wide single nucleotide polymorphism (SNP) data are available for 9863 individuals, and these are the individuals who are described and whose data are used in the present study (mean age = 52.2, SD = 13.64) (5788 female, 4075 male).
