Figure 2: Neonatal diagnosis for Hb S and Hb D-Punjab. Analysis of RBC lysates obtained from a dried blood spot obtained during the neonatal screening programme done in our laboratory. Analysis by two methods is required for the diagnosis. (A) Isoelectric focusing: Hb S and Hb D-Punjab have close isoelectric points and the resolution between the two bands is poor. The absence of HbA and thickening of HbS band help to diagnose. (B) Cation-exchange HPLC shows two abnormal peaks: one is eluted in S window and the other in the D window. (C) Capillary electrophoresis: (above): newborn heterozygous for Hb D-Punjab and (below): newborn heterozygous for Hb S. The two Hbs have different migrations.