GSTM1 and Schnyder corneal dystrophy: With this regard, Hb/Hp, and heme/Hpx complexes have been detected in plasma lipoproteins of SCD patients, with the ApoA-1 particles of HDL being more associated with heme/Hpx [154,155] and the LDL fraction containing higher concentrations of Hb/Hpx [155].