GSTM1 and granular corneal dystrophy type II: OPG likely shows sensitivity to the distribution of RA patients based on the sTfR-F index, as it tends to increase in the ACD subgroup (p = 0.053) compared to the combined anemia subgroup, as shown in Figure 1, but there is no significant difference in OPG levels between the subgroups based on Hb levels.