GSTM1 and glycogen storage disease VI: Loss of one (α+: -α3.7, -α4.2, αCS and αPS) or two (α°: --SEA and --THAI) α-globin gene/s on one chromosome generally presents as a silent carrier state, while loss of three (α+/α°) results in Hb H disease in which the pathology is primarily mediated by the relative excess of β-chains which can form tetramers of β-globin (β4) which can promote oxidative hemolysis.