Diagnostic Criteria and Evaluation of Severe Combined Immunodeficiency in the Neonate

Severe combined immunodeficiency disorders (SCID) are a group of primary immunodeficiencies resulting from any one of a diverse group of mutations impacting T-cell development. SCID is diagnosed and classified through assessment of the lymphocyte subset(s) affected and by the mechanisms responsible for the primary immune defect. Regardless of the genetics involved, patients invariably succumb to an early death without medical intervention. In the past, patients were primarily identified either by previous family history, physical manifestations, or after the onset of symptoms. However, the introduction of newborn screening for SCID has allowed the pediatrician to identify these patients at a much earlier age, greatly improving their survival. Currently, 23 states include SCID testing for T-cell deficiencies in their newborn screening platform. Protocols for confirmatory testing and medical intervention after a positive screen vary slightly from state-to-state. However, the standard curative treatment remains stem cell transplantation, although depending on the genetic cause of the disease, enzyme replacement and gene therapy may also be considered.