From a clinical perspective, α-thalassaemia is mostly a burden in Southeast Asia where α0-thalassaemia variants (e.g. --SEA, --THAI) are common and result in HbH disease when inherited with α+-thalassaemia (e.g. -α3.7 or -α4.2) or αND-thalassaemia (e.g. Hb Constant Spring, or Hb CS, or Hb Paksé), or in Hb Bart’s hydrops fetalis when inherited from both parents (Weatherall et al., 2006; Chui, 2005). The gene discussed is GSTM1; the disease is hemoglobin H disease.