Characterization of Three Novel δ Chain Hemoglobin Variants and Two δ-Thalassemia Alleles

We report the characterization of five novel delta-globin gene mutations detected during routine screening for thalassemia. Three missense mutations were identified, resulting in the following delta chain hemoglobin (Hb) variants: Hb A(2)-Acacias [delta4 (ACT>AGT), Thr-->Ser, HBD c.14C>G], Hb A(2)-Toronto [delta74 (GGC>GAC), Gly-->Asp, HBD c.224G>A], and Hb A(2)-Calgary [delta99 (GAT>GGT), Asp-->Gly, HBD c.299A>G]. Two other mutations most likely result in delta(0)-thalassemia (delta(0)-thal). One mutation altered the translation initiation codon from ATG to ATA (HBD c.3G>A), and another changed the canonical splice donor sequence of IVS-II from GT to AT (HBD C.315+1G>A).