GSTM1 and thalassemia: On classifying patients into those with heterozygous α0-thalassemia, heterozygous deletional α+-thalassemia, homozygous deletional α+-thalassemia, and compound heterozygotes (deletional/nondeletional), we observed that alpha + homozygous genotype had the lowest Hb and RBCs and highest mean of ferritin; this can be explained by that poly A homozygous genotype is more severe and may behave as HbH, a result similar to that reported in United Arab Emirates [33].