The study was approved by the necessary Institutional Review Boards of all involved institutions. Signed informed-consent documents were obtained from all study participants before they entered the study. For our GWAS, a random sample containing 840 unrelated Caucasians was identified from our established and expanding genetic repertoire currently containing more than 6,000 subjects. All of the chosen subjects were US Caucasians of European origin living in Omaha, Nebraska and its surrounding areas. They were healthy subjects recruited for genetic research of common human complex traits, such as bone mineral density and body mass index. Detailed recruitment and exclusion criteria were published elsewhere (15). Briefly, subjects with chronic diseases and conditions involving vital organs (heart, lung, liver, kidney, and brain) and severe endocrinological, metabolic, and nutritional diseases were excluded from this study. The general relevant characteristics of the study subjects are listed in Table 1.
