Similarly to SCD, other hemoglobinopathies can be triggered by the substitution of one amino acid (HbE5,6,2), deletion of a portion of the amino acid sequence (Hb Gun Hill7), abnormal hybridization between two chains (Hb Lepore8,9), or abnormal elongation of the globin chain (Hb Constant Spring10). Here, GSTM1 is linked to Schnyder corneal dystrophy.