Newborn screening for sickling and other haemoglobin disorders using tandem mass spectrometry: A pilot study of methodology in laboratories in England

Objective: To determine (i) if electrospray mass spectrometry-mass spectrometry with the SpOtOn Diagnostics Ltd reagent kit for sickle cell screening could be integrated into the English newborn screening programme, under routine screening conditions, and provide mass spectrometry-mass spectrometry results which match existing methods, and (ii) if common action values could be set for all manufacturers in the study, for all assessed haemoglobins, to indicate which samples require further investigation. Methods: Anonymised residual blood spots were analysed using the SpOtOn reagent kit as per manufacturer’s instructions, in parallel with existing techniques at four laboratories. Mass spectrometry-mass spectrometry instrumentation at Laboratories A and B was AB Sciex (Warrington, UK) AP4000, and at Laboratories C and D,Waters Micromass (Manchester, UK), Xevo TQMS and Premier, respectively. Results: There were 23,898 results accepted from the four laboratories. Excellent specificity at 100% sensitivity was observed for haemoglobin S, haemoglobin C, haemoglobin E and haemoglobin O^Arab. A common action value was not possible for Hb C, but action values were set by manufacturer. The two haemoglobin D^Punjab cases at Laboratory D were not detected using the common action value. Conversely, false-positive results with haemoglobin D^Punjab were a problem at the remaining three laboratories. Conclusions: This multicentre study demonstrates that it is possible to implement mass spectrometry-mass spectrometry into an established screening programme while maintaining consistency with existing methods for haemoglobinopathy screening. However, one of the instruments investigated cannot be recommended for use with this application.