摘要：Abstract In Manitoba, Canada, the overall incidence of Severe Combined Immunodeficiency (SCID) is three-fold higher than the national average, with {SCID} overrepresented in two population groups: Mennonites and First Nations of Northern Cree ancestries. T-cell receptor excision circle (TREC) assay is being used increasingly for neonatal screening for {SCID} in North America. However, the majority of {SCID} patients in Manitoba are T-cell-positive. Therefore it is likely that the {TREC} assay will not identify these infants. The goal of this study was to blindly and retrospectively perform {TREC} analysis in confirmed {SCID} patients using archived Guthrie cards. Thirteen {SCID} patients were tested: 5 T-negative {SCID} (3 with adenosine deaminase deficiency, 1 with CD3δ deficiency, and 1 unclassified) and 8 T-positive {SCID} (5 with zeta chain-associated protein kinase (ZAP70) deficiency and 3 with inhibitor of kappa light polypeptide gene enhancer in B-cells, kinase beta (IKKβ) deficiency). As a non-SCID patient group, 5 Primary Immunodeficiency Disease (PID) patients were studied: 1 T-negative {PID} (cartilage-hair hypoplasia) and 4 T-positive {PID} (2 common immune deficiency (CID), 1 Wiskott–Aldrich syndrome, and 1 X-linked lymphoproliferative disease). Both patient groups required hematopoietic stem cell transplantation. In addition, randomly-selected de-identified controls (n = 982) were tested. Results: all T-negative {SCID} and {PID} had zero TRECs. Low-TRECs were identified in 2 {ZAP70} siblings, 1 {CID} patient as well as 5 preterm, 1 twin, and 4 de-identified controls. Conclusions: {TREC} method will identify T-negative {SCID} and T-negative PID. To identify other {SCID} babies, newborn screening in Manitoba must include supplemental targeted screening for ethnic-specific mutations.
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