The major specific aims are: Aim 1. Test for inflammatory genetic effects and protein level in CAAD progression in 550 subjects with CAAD (275 with 15-49% and 275 with 50-79% baseline CAAD stenosis) evaluated by 3-year magnetic resonance image follow-up of percent lumen stenosis; Aim 2. Determine whether the variation in the inflammatory genes or protein levels predicts 810 case vs. 810 control status with a case distribution of 335 subject with 15-49%, 275 with 50-75% and 200 with >80% carotid artery stenosis at baseline. Age (onset of vascular disease for cases, current age for controls)-, sex-, race-, and hospital-matched controls will have less than 15% stenosis on carotid duplex ultrasound. Genes that are implicated in disease may eventually allow targeted therapy.