SCD is caused by a single nucleotide substitution that results in the replacement of the glutamic acid at position 6 with valine of the β-subunit (β-Glu6Val) of hemoglobin (Hb), leading to polymerization of the β-globin chains of the abnormal sickle hemoglobin (HbS) when in the deoxygenated T-state, the formation of rigid, insoluble HbS fibers, and subsequent red blood cell (RBC) sickling5–10. Here, GSTM1 is linked to Schnyder corneal dystrophy.