6
Diagnosis
Section 2. Newborn Screening for Severe Combined
Immunodeficiency and Athymia — Diagnostic and Initial
Approach
Recommendation 2.1
➤ We recommend T-cell receptor excision circle (TREC) quantitation for
newborn population-based screening for the early identification of
newborns with SCID and complete athymia. (S-H)
Recommendation 2.2
➤ We recommend the urgent confirmation of an abnormal universal
newborn screening (NBS) for SCID with complete blood counts with
differential and flow cytometric measurement of peripheral blood
lymphocyte subset populations, including assessment of numbers of
T, B, and natural killer (NK) subsets and naive T cells. (S-H)
Recommendation 2.3
➤ We recommend that diagnostic evaluation for SCID and athymia
includes genetic testing, ascertainment of maternal T-cell
engraftment, IgE levels, eosinophilia, T-cell oligoclonality, T-cell
proliferation, and adenosine deaminase (ADA) enzyme activity. (S-H)
Recommendation 2.4
➤ We recommend urgent referral to centers with expertise in the care
of severe immunodeficiency after a SCID or athymia diagnosis is
confirmed. (S-H)
Recommendation 2.5
➤ We recommend referral to clinician with expertise in IEI for
assessment and diagnosis of patients with non-SCID T-cell
lymphopenia detected by NBS. (S-M)
