HLA-DRB1 and Vascular dilatation: Strikingly, patients with progressive aortic root dilatation (mean aortic dilatation rate of 0.9 mm/year) had an increased expression of HLA-DRB1 and HLA-DRB5 genes (r = 0.56 for both; FDR = 0%) (Figure 2) when compared to the patients with low aortic root dilatation rate (mean aortic dilatation rate of 0.1 mm/yr).