Vitamin D, vitamin D binding protein gene polymorphisms, race and risk of incident stroke: the Atherosclerosis Risk in Communities (ARIC) study

Background and purpose Low vitamin D levels, measured by serum 25‐hydroxyvitamin D [25(OH)D], are associated with increased stroke risk. Less is known about whether this association differs by race or D binding protein (DBP) single nucleotide polymorphism (SNP) status. Our objective was to characterize the associations of and interactions between 25(OH)D levels and DBP SNPs with incident stroke. It was hypothesized that associations of low 25(OH)D with stroke risk would be stronger amongst persons with genotypes associated with higher DBP levels. Methods 25(OH)D was measured by mass spectroscopy in 12 158 participants in the Atherosclerosis Risk in Communities (ARIC) study (baseline 1990–1992, mean age 57 years, 57% female, 23% black) and they were followed through 2011 for adjudicated stroke events. Two DBP SNPs (rs7041, rs4588) were genotyped. Cox models were adjusted for demographic/behavioral/socioeconomic factors. Results During a median of 20 years follow‐up, 804 incident strokes occurred. The lowest quintile of 25(OH)D (