The compound heterozygotes for Hb O-Arab and the β-thalassemia variant typically manifested mild to moderate anemia, and the hematological characteristics and clinical manifestations of individuals with Hb O-Arab combined with β0-thalassemia individuals were considerably more severe than those of individuals with Hb O-Arab combined with β+-thalassemia individuals (Moumni et al., 2011; Morlé et al., 1984; Kantchev et al., 1975; Rachmilewitz et al., 1985; Kalai et al., 2024), indicating that β-thalassemia variants were the main contributors to the phenotypic variability in these individuals. This evidence concerns the gene GSTM1 and anemia (phenotype).