Screening Test Evaluated for Sickle Cell Disease

Two methods used routinely for screening neonatal blood for abnormal hemoglobins have been compared with an electrophoretic method for hemolysates.

Results from a high-pressure liquid chromatography (HPLC) screening method are customarily confirmed by isoelectric electric focusing (IEF) to determine whether abnormal hemoglobinopathies are present in newborn infant's blood.

In a study carried out by the West Midlands Newborn Screening Laboratory (Birmingham Children’s Hospital, UK) a capillary electrophoresis system was evaluated as a possible replacement for other methods. With this technique, charged molecules are separated by their electrophoretic mobility in an alkaline buffer with a specific pH. Separation also occurs according to the electrolyte pH and electro-osmotic flow. Individual hemoglobins are separated using silica capillaries and buffers provided by the manufacturers. These hemoglobins are then detected at a wavelength of 415 nm. The resulting electrophoretograms are evaluated on screen to detect pattern abnormalities with software identifying normal and pathological patterns.

Three hundred and forty-seven blood spot specimens were analyzed first using the VARIANT newborn screening (Vnbs) HPLC method (Bio-Rad Laboratories Ltd.; Hertfordshire, UK). Any abnormal hemoglobin found was confirmed by the Resolve IEF kit supplied by Perkin-Elmer (Seer Green, UK). These specimens were then analyzed using the Capillary Neonat Hemoglobin FAST system (Sebia; Norcross, GA, USA) to compare peak identity and in a selection the percentage peak integration areas.

The Sebia-recommended sample preparation had to be modified to enable testing to be more comparable with current processes. Percentages of hemoglobins calculated from integration of areas under the peaks were compared between the Bio-Rad Vnbs HPLC and Sebia Capillarys Neonat Haemoglobin FAST system. Of the 347 blood spots tested by both HPLC and capillary electrophoresis, there were no significant differences. The Sebia Capillarys Neonat Haemoglobin FAST system can be used to screen newborns successfully for sickle cell disease in blood spots collected for newborn screening with full positive sample identification and traceability. Result analysis of newborn samples is simplified by multiple factors.

The Capillary 2 Neonat Fast system provides newborn results free of extraneous peaks. Newborn results are automatically color-coded, green for normal or red for abnormal, in order to easily distinguish abnormal results, which are also sortable and printable. All newborn results are stored electronically, easily recalled, and traceable from start to finish – true positive sample identification. The study was published for the October 2011 edition of the International Journal of Laboratory Hematology.

Related Links:
Birmingham Children’s Hospital
Bio-Rad
Sebia