Common hemoglobin variants affecting the diagnosis of β-thalassemia: A large cohort data at a single center

BACKGROUND: Many globin chain variants were interpreted as β-thalassemia or hereditary persistence of fetal hemoglobin (HPFH) at routine investigation. We described this in a large cohort of Thai subjects. METHODS: Hematological data of 43,414 subjects encountered at our thalassemia diagnostic center from January 2013 to July 2025 were reviewed. A total of 372 subjects with hemoglobin (Hb) variants were selectively recruited with leftover DNA specimens for further analysis. Hb analysis was done using high-performance liquid chromatography (HPLC) or capillary electrophoresis. β-globin gene mutations were identified using PCR and related techniques. RESULTS: Among 372 subjects recruited, a total of 21 different Hb variants were found. The levels of Hb A2, Hb F, Hb variants, and DNA diagnostic requests were recorded. Hb variants with normal Hb A2 and Hb F levels were requested for β-thalassemia or HPFH in 12.3% (95% CI = 7.9-16.8). This error was increased in Hb variants with Hb A2 ≥ 3.6% [50.6% (95% CI = 39.8-61.4) and odds ratio of 7.3 (3.6-13.8)] and Hb F ≥ 5.0% [52.2% (95% CI = 37.7-66.6) and odds ratio of 7.8 (3.6-16.7)], especially in those with Hb A2 ≥ 3.6% and Hb F ≥ 5.0% [71.9% (95% CI = 56.3-87.5) and odds ratio of 18.2 (7.1-48.9)]. Hbs Hope, Tak, Cook, C, Lepore, and Q-Thailand were found to be associated with high proportions of the error. CONCLUSIONS: Hb variants with increased Hb A2 levels and/or co-migration with Hb F are associated with a high proportion of mis-interpretation of β-thalassemia in routine practice. Combining Hb analysis using two different methods, and molecular analysis should help improve laboratory interpretation of the cases.