Newborn Screening for Severe Combined Immunodeficiency

Immunol Allergy Clin North Am. 2021 Nov;41(4):543-553. doi: 10.1016/j.iac.2021.07.007.


The T-cell receptor excision circle (TREC) assay is an effective screening tool for severe combined immunodeficiency (SCID). The TREC assay was designed to detect typical SCID and leaky SCID, but any condition causing low naïve T-cell counts will also be detected. Newborn screening for SCID using the TREC assay has proven itself to be highly sensitive and cost-efficient. This review covers the history of SCID newborn screening, elaborates on the SCID subtypes and TREC assay limitations, and discusses diagnostic and management considerations for infants with a positive screen.

Keywords: Newborn screening (NBS); Severe combined immunodeficiency (SCID); T-cell lymphopenia; T-cell receptor excision circle (tREC).

Publication types

  • Review

MeSH terms

  • Humans
  • Infant, Newborn
  • Lymphopenia*
  • Neonatal Screening
  • Receptors, Antigen, T-Cell / genetics
  • Severe Combined Immunodeficiency* / diagnosis
  • Severe Combined Immunodeficiency* / therapy


  • Receptors, Antigen, T-Cell