Consistently, SCD individuals with a rare second mutation, αAsn78→Lys (Hb Stanleyville) or βAsp73→Val (Hb Mobile), on the αF-helix of Hb show reduced tendency for HbS polymerization and RBC sickling, resulting in mild or even no disease sequelae (Benesch et al., 1979; Rhoda et al., 1983; Burchall and Maxwell, 2010; Pagare et al., 2022). Here, GSTM1 is linked to Schnyder corneal dystrophy.