Increased mortality in infants with abnormal T-cell receptor excision circles

Background T-Cell Receptor Excision Circles based newborn screening (TREC-NBS) allows for early detection of T-cell lymphopenia in infants with primary immunodeficiency disorders (PIDD). The utility of abnormal TREC-NBS in infants without PIDD is not well studied. We sought to evaluate the association of abnormal TREC-NBS with mortality. Methods 365,207 TREC-NBS from October 2011 to December 2014 were reviewed. 467 newborns had abnormal screens and did not meet the criteria for a PIDD diagnosis. Cases were matched to controls (1:3) based on gestational age, birth weight, neonatal intensive care unit status (NICU), and race. Data were obtained through NBS, birth and death certificates records from the Michigan Department of Health and Human Services (MDHHS) databases. Results Infants with abnormal TREC-NBS had higher mortality even when PIDD was ruled-out. Transient abnormal TREC-NBS was not associated with higher mortality, but unresolved or late abnormal TREC-NBS was associated with higher mortality. Infants with late abnormal TREC-NBS had severe prematurity, lower birth weight, lower Apgar scores, and higher percentage of congenital anomalies. Conclusion Infants with abnormal TREC-NBS may be at a higher risk of morbidity and mortality and should be carefully followed, especially if discharged home before a repeat screen can be completed. Impact This study explores the risk factors and mortality for newborns with secondary T-cell lymphopenia captured on T-Cell Receptor Excision Circles based newborn screening (TREC-NBS). Abnormal TREC-NBS allows for prompt life-saving interventions for primary immunological conditions such as Severe Combined Immunodeficiency (SCID), but can also be associated with non-immunologic conditions. Unresolved and late abnormal TREC-NBS is associated with higher mortality even without primary immunodeficiency, likely detected in infants with more severe prematurity, lower birth weight, and congenital anomalies. TREC-NBS positive infants with secondary T-cell lymphopenia require special attention and close monitoring.