Newborn Screening in the Diagnosis of Primary Immunodeficiency.

Newborn screening for severe combined immune deficiency (SCID) is the first inborn error of immunity (IEI) to be detected through population screening. It also represents the first newborn screening test to utilize molecular testing on DNA from newborn dried blood spots. Newborn screening for SCID has provided opportunities to measure the population prevalence of this disorder and evaluate the effect of early interventions on the overall outcomes in affected infants. The success of SCID newborn screening has increased interest in developing and implementing molecular testing for other clinically significant inborn errors of immunity. This methodology has been adapted to screen for another monogenic inborn defect, spinal muscle atrophy. Advances in the clinical care and new therapeutics for many inborn errors of immunity support the need for early diagnosis and prompt institution of therapies to reduce morbidity and mortality. Early diagnosis may also improve the quality of life for affected patients. This article provides an overview of newborn screening for SCID, recommended steps for follow-up testing and early intervention as well as long-term follow-up. Numerous challenges remain, including the development of clinical consensus regarding confirmatory and diagnostic testing, early interventions, and best practices for immune reconstitution in affected infants.