SCD is an autosomal recessive disorder and can be clinically expressed either by receiving two copies of hemoglobin (Hb) S (sickle cell anemia) or one copy of HbS plus another β-globin variant (such as HbC, β-thalassemia, HbD, or HbE) [7]. Here, GSTM1 is linked to Schnyder corneal dystrophy.