Newborn screening; Severe combined immunodeficiencyCribatge nounat; Immunodeficiència combinada severaCribado neonato; Inmunodeficiencia combinada gravePurine nucleoside phosphorylase (PNP) deficiency is a rare inherited disorder, resulting in severe combined immunodeficiency. To date, PNP deficiency has been detected in newborn screening only through the use of liquid chromatography tandem mass spectrometry. We report the first case in which PNP deficiency was detected by TREC analysis.This research was funded by Jeffrey Modell Foundation