Rapid molecular characterization of Hb Queens and Hb Siam: Two variants easily misidentified as sickle Hb

Objective: To establish a rapid differential diagnosis of hemoglobin (Hb) Queens and Hb Siam from other clinically relevant variants. Design and methods: Molecular and hematological features associated with two pregnant Thai women who were mistaken for Hb S were investigated. A simultaneous DNA diagnosis based on multiplex allele specific PCR approach was developed and tested with other common variants. Results: Apart from mild anemia, the two subjects were generally healthy. DNA analysis identified that they were respectively carriers of Hb Siam [α15(A13)Gly–Arg] and Hb Queens [α34(B15)Leu–Arg]. A successful application of the multiplex allele specific PCR for differential diagnosis was demonstrated. Conclusion: Diagnosis of these clinically relevant hemoglobinopathies is problematic in the routine setting, and the method developed should prove useful in complementing routine Hb analysis for providing accurate diagnosis.