A metabolic signature of SCD patients and young RBCs can be obtained from LC/MS analysis of RBC extracts. Metabolite exhibiting significant concentration variations between controls and SCD patients. Values are ratios of individual levels observed for SCD patients (red points) and controls (green points) to mean levels obtained for healthy subjects. Statistically significant difference observed with a t test: *.01 < P < .05, **.001 < P < .01, ***P < .001. (A) Metabolites whose levels are decreased in SCD patients. (B) Metabolites whose levels are increased in SCD patients. (C) Metabolites whose levels are decreased in SCD patients were analyzed in young normal RBCs. (D) Metabolites whose levels are increased in SCD patients were analyzed in young normal RBCs. Values are ratios of mean levels observed for SCD patients and controls (red panel), compared with ratios of mean levels found for young RBCs and all aged RBCs (blue panel).