In particular, our model predicts the dynamics of the accumulation of ribavirin in RBCs and the resulting decline of Hb in patients following the onset of therapy, estimates the reduced lifespan of RBCs during therapy, and describes inter-patient variations in the severity of anemia, thus presenting a robust description of ribavirin-induced anemia, which, in conjunction with models of viral kinetics, may facilitate identification of treatment protocols that maximize the impact of ribavirin in the treatment of HCV infection. Here, GSTM1 is linked to anemia (phenotype).