Recently, Giulietti et al. (Giulietti et al., 2022) studied in-depth immunological alterations in SCD with many findings which were similar to the ones that we observed in SCD population (increase in WBC and neutrophils, decrease in CD3+ cells and CD4+ cells, increase in CD4+ central memory T cells), but, in addition, they observed immunological alteration probably consequent to the use of hydroxyurea. Here, CD4 is linked to Schnyder corneal dystrophy.