Further, while GDF15 may be a marker of subclinical atherosclerosis or endothelial damage, this study was limited in the assessment of endothelial damage due to the lack of availability of von Willebrand factor levels.41,42 Another limitation of CVD biomarker assessments in biological samples lies in the considerable diurnal variation in their concentrations, as reported by previous studies.43 As stated previously, ours was a single-study, with an observational sample design, and thus our results need to be considered hypothesis-generating. The gene discussed is VWF; the disease is atherosclerosis.