Newborn screening algorithm for severe combined immunodeficiency (SCID) in California

SCID NBS algorithm developed in California. Infants are categorized according to TREC copy numbers, beta-actin gene segment amplification, and nursery as proxy for clinical status. Urgent positive and positive cases are recalled for flow cytometry. Incomplete cases (infants with DNA amplification failure results and nonurgent positive infants in NICU) are recalled for a repeat dried blood spot sample for TREC and beta-actin determination. Infants with 2 low TREC results are also recalled for flow cytometry. Results are interpreted by designated consultant immunologists, and abnormal results trigger referral for further investigation.