Differences in the mean leukocyte count, CD3+ (PAN-T) cell% and CD4+ effector memory T-cell% were the only parameters maintaining statistical significance both between the SCD HU− and HU+ subgroups and between the SCD HU− subgroup and controls, but not between the SCD HU+ subgroup and controls (Figure 1a–c). Here, CD4 is linked to Schnyder corneal dystrophy.