Statewide Newborn Screening for Severe T-Cell Lymphopenia

Abstract

Context A newborn blood screening (NBS) test that could identify infants with a profound deficiency of T cells may result in a reduction in mortality. Objective To determine if quantitating T-cell receptor excision circles (TRECs) using real-time quantitative polymerase chain reaction on DNA extracted from dried blood spots on NBS cards can detect infants with T-cell lymphopenia in a statewide program. Design, setting, and participants Between January 1 and December 31, 2008, the Wisconsin State Laboratory of Hygiene screened all infants born in Wisconsin for T-cell lymphopenia by quantitating the number of TRECs contained in a 3.2-mm punch (approximately 3 microL of whole blood) of the NBS card. Flow cytometry to enumerate the number of T cells was performed on full-term infants and preterm infants when they reached the equivalent of at least 37 weeks' gestation with TREC values of less than 25/microL. Infants with T-cell lymphopenia were evaluated by a clinical immunologist. Main outcome measures The number of infants with TREC values of less than 25/microL with T-cell lymphopenia confirmed by flow cytometry. Results Exactly 71,000 infants were screened by the TREC assay. Seventeen infants aged at least 37 weeks' gestation had at least 1 abnormal TREC assay (TREC values Conclusion In a statewide screening program, use of the TREC assay performed on NBS cards was able to identify infants with T-cell lymphopenia.