GSTM1 and thalassemia: Moreover, in a study where red blood cell indices such as Hb, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean cell hemoglobin concentration (MCHC) were investigated among normal, α-thalassemia-1 trait9 (two alpha gene defects), and Hb Barts fetuses, it revealed that these basic data are valuable in differentiating the affected fetuses among couples at risk10.