The number of circulating CD34+ progenitor cells were significantlyupregulated in AD patients (mean absolute cell count±SD: 253±51 vs.203±37; P = 0.02) (Fig. 1C).Moreover, we found a significant, inverse correlation with the plasma levels ofleptin (r = −0.248; P = 0.037)(Fig.1D). This evidence concerns the gene CD34 and Alzheimer disease.