GSTM1 and anemia (phenotype): Before the age of 1 year, SCD patients are relatively protected from anemia and organ pathology by increased HbF levels.36,37 BERK SCD mice are anemic at an early age, as indicated by reduced total Hb and RBC counts compared to wild-type Bl6 mice and heterozygous SCD (SCD Hz) controls (Supplementary Figure S4a,b).