Genetic interactions of different defective globin chains could render laboratory diagnostics in a routine setting difficult. We report a hitherto undescribed condition of double heterozygosity for hemoglobin (Hb) Q-Thailand with α+-thalassemia and Hb Tak found in 2 adult Thai individuals. Both patients were healthy and had no pertinent past medical history. A complete blood count revealed slight elevations of Hb and HCT values with low MCV and MCH. Interestingly, Hb analysis demonstrated, in addition to Hb A, A2, and F, as many as 5 Hb variants including Hb Tak (αA2βTak2), Q-Thailand (αQT2βA2), QA2QT2δ2), QF (αQT2γ2), and a novel variant, Hb QTak (αQT2βTak2). Hematological findings of these unusual cases were compared with those of pure heterozygotes for Hb Q-Thailand and Hb Tak found in our series. Hb analysis using combined HPLC and capillary electrophoresis did help in the initial recognition and in making presumptive diagnoses, but definite diagnoses of these cases with complex α- and β-hemoglobinopathies could only be obtained after DNA analysis.

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