Coinheritance of Hb D-Punjab and β-thalassemia: diagnosis and implications in prenatal diagnosis

Hb D-Punjab (HBB: c.364G>C) is an abnormal hemoglobin (Hb) associated with genetic risk in association with Hb S (HBB: c.20A>T). In addition, misdiagnosing homozygosis for hemizygosis may have implication for genetic risk assessment. We present the diagnostic utility of high performance liquid chromatography (HPLC) in differential diagnosis between the Hb D-Punjab homozygote and the Hb D-Punjab/β-thalassemia (β-thal) genotype. The Hb A2 level measurement may not be a reliable parameter to differentiate between the two conditions. In a screening program for risk prediction, the genotype should be confirmed by family study and/or molecular analysis. Misdiagnosis can have potentially adverse implications in a prenatal diagnosis (PND) program, particularly in areas where consanguinity is common and this Hb D-Punjab variant occurs.