Children with a VOE alone receiving RBC transfusion (n = 28) differed significantly from non-transfused children (n = 128), in terms of anemia severity (mean Hb level 8.1 (±1.7) vs. 9.2 (±1.4), p = 0.0001) and FPS at admission (7.6 (±2.9) vs. 6.4 (±2.6), p = 0.03). The gene discussed is GSTM1; the disease is anemia (phenotype).