First Report of a Chinese Family Carrying a Double Heterozygosity for Hb Q-Thailand and Hb J-Bangkok

The double heterozygosity for alpha and beta chain variants leads to the formation of abnormal heterodimer hybrids, which could render laboratory diagnostics in a routine setting difficult. The following is the first report of a double heterozygosity for Hb Q-Thailand [alpha 74(EF3) Asp -> His; HBA1: c. 223G> C] with alpha(+) thalassemia (alpha(+) thal) and Hb J- Bangkok [beta 56(D7) Gly -> Asp; HBB: c. 170G> A] found in a Chinese family. Both subjects were healthy with normal or borderline hematological parameters. Hemoglobin (Hb) analyses showed a novel variant, Hb Q- Thailand and Hb J- Bangkok. Family studies helped in the initial recognition and in making presumptive diagnoses, but definitive diagnoses of these cases with complex a and b chain variants could only be obtained after DNA analysis.