COASY and myelodysplastic syndrome: Furthermore, silencing of COASY in CD34+ HSPCs caused significant delays in erythroid differentiation (p<0.01), with accumulation of erythroblasts CD71+CD235a+, fewer mature cells than CD71-CD235a+ (Fig 5I), and a decrease in 5-aminolevulinate and heme production (Fig. S5C & Fig 5J) that resembles the clinical phenotype of primary MDS-RS samples from patients.