The aim of this study was to determine the hematological characteristics in a large group of Hb H (β4) patients with or without a coexisting β-thalassemia (β-thal), identified by a thalassemia screening program in mainland China. A total of 361 patients with Hb H disease were found, including 343 with deletional types and 18 with nondeletional types. β-Thalassemia was found in 28 (7.8%) out of the 361 Hb H cases, and all of the 28 cases had the deletional type of Hb H disease. Lower hemoglobin (Hb) levels were detected in cases with the nondeletional type compared to those in cases with the deletional type. β-Thalassemia significantly increases the Hb levels in Hb H cases. The Hb H and Hb Bart's (γ4) fractions were visible in 270 (85.7%) and 122 (38.7%) out of 315 deletional type cases, respectively, while no Hb H or Hb Bart's fractions were detectable in 28 deletional type cases with β-thal. Therefore, the diagnosis of Hb H disease in a β-thal carrier is challenging. Molecular analysis of α- and β-globin genes is imperative in all cases with a β-thal trait.
Keywords: Hb H disease; genetic association; α-Thalassemia (α-thal); β-thalassemia (β-thal).