Experience with newborn screening using isoelectric focusing.

Electrophoretic techniques are used for hemoglobinopathy diagnosis. Confirmation of the hemoglobin variants is necessary. Currently, citrate agar electrophoresis is the most available, but high performance liquid chromatography is highly recommended in a reference laboratory. Thin layer isoelectric focusing is an excellent technique that can be easily adapted for large-scale newborn hemoglobinopathy screening. Although the initial instrument cost can be about twice as much as the cost for standard electrophoretic equipment, cost-effectiveness for newborn screening is considerable because repeat analysis for uninterpretable results is not necessary. Resolution of hemoglobins is much better with thin layer isoelectric focusing than for any of the other electrophoretic methods currently available, and thin layer isoelectric focusing is the best method to use to establish a definitive diagnosis using newborn blood samples. Cord blood samples may be contaminated with maternal blood, and evaluation of Hb A2 levels in such samples can serve as the method to detect contamination. Follow-up testing is required regardless of the method of blood collection.