GSTM1 and Schnyder corneal dystrophy: For example, in SCD, the Hb polymerization is the main issue undermining RBC deformability (Huang et al., 2003), whereas, in pyruvate kinase deficiency, decreased deformability is presumably based on insufficient ATP production leading to deregulation of membrane channel function and impaired ion homeostasis (Rab et al., 2021).