Hb S-β-Thalassemia: Molecular, Hematological and Clinical Comparisons

Abstract

Clinical and hematological features are presented for 261 patients with identified β-thalassemia (β-thal) mutations. Mutations causing Hb S [β6(A3)Glu→Val]-β⁰-thal were IVS-II-849 (A>G) in 44%, frameshift codon (FSC) 6 (–A) in 14%, Hb Monroe [β30(B12)Arg→Thr] in 14%, and IVS-II-1 (G>A) in 10%. Mutations causing Hb S-β⁺-thal with 14-25% Hb A (type III) were –29 (A>G) mutation in 60%, –88 (C>T) in 22% and the polyadenylation signal site (polyA) (T>C) mutation in 14%, and in Hb S-β⁺-thal with 1-7% Hb A (type I), all had the IVS-I-5 (G>C) mutation. Hematologically, only minor differences occurred between the four Hb S-β⁰-thal mutations, but among the three mutations causing Hb S-β⁺-thal type III, levels of Hb A₂, Hb F, hemoglobin (Hb), MCV and MCH were highest in the –88 and lowest in the polyA mutations. Clinically, Hb S-β⁰-thal and Hb S-β⁺-thal type I were generally severe, and Hb S-β⁺-thal type III disease with the –88 mutation was milder than that caused by the polyA mutation.

• Hb S-β⁺-thalassemia (β⁺-thal)
• Hb S-β⁰-thalassemia (β⁰-thal)
• Thalassemia mutations
• β⁺-Thalassemia (β⁺-thal) trait
• β⁰-Thalassemia (β⁰-thal) trait