{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T17:05:16Z","timestamp":1790096716778,"version":"4.0.1"},"reference-count":34,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2024,7,15]],"date-time":"2024-07-15T00:00:00Z","timestamp":1721001600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Immunodeficiency Canada\u2019s Distinguished Professorship in Immunology"},{"name":"Canadian Centre for Primary Immunodeficiency"},{"name":"Jeffrey Modell Foundation"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Genes"],"abstract":"<jats:p>Background: Severe combined immunodeficiency (SCID) is a life-threatening genetic disorder caused by critical defects of the immune system. Almost all cases are lethal if not treated within the first two years of life. Early diagnosis and intervention are thus essential for improving patient outcomes. In 2013, Ontario became the first Canadian province to perform newborn screening (NBS) for SCID by T cell receptor excision circles (TRECs) analysis, a surrogate marker of thymic function and lymphocyte maturation. Methods: This retrospective study reports on nearly 10 years of NBS for SCID at a quaternary referral centre. Results: From August 2013 to April 2023, our centre\u2019s densely populated catchment area flagged 162 newborns with low TRECs levels, including 10 cases with SCID. Follow-up revealed other causes of low TRECs, including non-SCID T cell lymphopenia (secondary\/reversible or idiopathic causes, and syndromic conditions) and prematurity. A small number of cases with normal repeat TRECs levels and\/or T cell subsets were also flagged. Province-wide data from around this period revealed at least 24 diagnosed cases of SCID or Leaky SCID. Conclusions: This is the first report of NBS outcomes in a Canadian province describing the causative genetic defects, and the non-SCID causes of a positive NBS for SCID.<\/jats:p>","DOI":"10.3390\/genes15070920","type":"journal-article","created":{"date-parts":[[2024,7,15]],"date-time":"2024-07-15T18:17:32Z","timestamp":1721067452000},"page":"920","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["A Unique Comprehensive Model to Screen Newborns for Severe Combined Immunodeficiency\u2014An Ontario Single-Centre Experience Spanning 2013\u20132023"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0009-0003-1582-7203","authenticated-orcid":false,"given":"Abdulrahman","family":"Al Ghamdi","sequence":"first","affiliation":[{"name":"Division of Immunology & Allergy, Department of Pediatrics, Hospital for Sick Children, University of Toronto, Toronto, ON M5S 1A1, Canada"},{"name":"Department of Pediatrics, King Faisal Specialist Hospital and Research Center Ar Rawdah, Jeddah 23433, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jessica Willett","family":"Pachul","sequence":"additional","affiliation":[{"name":"Division of Immunology & Allergy, Department of Pediatrics, Hospital for Sick Children, University of Toronto, Toronto, ON M5S 1A1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Azhar","family":"Al Shaqaq","sequence":"additional","affiliation":[{"name":"Division of Immunology & Allergy, Department of Pediatrics, Hospital for Sick Children, University of Toronto, Toronto, ON M5S 1A1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Meghan","family":"Fraser","sequence":"additional","affiliation":[{"name":"Newborn Screening Program, Department of Clinical and Metabolic Genetics, Hospital for Sick Children, University of Toronto, Toronto, ON M5S 1A1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Abby","family":"Watts-Dickens","sequence":"additional","affiliation":[{"name":"Newborn Screening Program, Department of Clinical and Metabolic Genetics, Hospital for Sick Children, University of Toronto, Toronto, ON M5S 1A1, Canada"},{"name":"Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nicole","family":"Yang","sequence":"additional","affiliation":[{"name":"Newborn Screening Program, Department of Clinical and Metabolic Genetics, Hospital for Sick Children, University of Toronto, Toronto, ON M5S 1A1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Linda","family":"Vong","sequence":"additional","affiliation":[{"name":"Division of Immunology & Allergy, Department of Pediatrics, Hospital for Sick Children, University of Toronto, Toronto, ON M5S 1A1, Canada"},{"name":"Canadian Centre for Primary Immunodeficiency, Hospital for Sick Children, University of Toronto, Toronto, ON M5S 1A1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Vy H. D.","family":"Kim","sequence":"additional","affiliation":[{"name":"Division of Immunology & Allergy, Department of Pediatrics, Hospital for Sick Children, University of Toronto, Toronto, ON M5S 1A1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0151-8111","authenticated-orcid":false,"given":"Victoria Mok","family":"Siu","sequence":"additional","affiliation":[{"name":"Division of Medical Genetics, Department of Pediatrics, London Health Sciences Centre, Western University, London, ON N6A 5A5, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anne","family":"Pham-Huy","sequence":"additional","affiliation":[{"name":"Division of Infectious Diseases, Immunology and Allergy, Children\u2019s Hospital of Eastern Ontario, Faculty of Medicine, University of Ottawa, Ottawa, ON K1N 6N5, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0038-9699","authenticated-orcid":false,"given":"Rae","family":"Brager","sequence":"additional","affiliation":[{"name":"Division of Rheumatology, Immunology, and Allergy, Department of Paediatrics, McMaster Children\u2019s Hospital, McMaster University, Hamilton, ON L8S 4L8, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Brenda","family":"Reid","sequence":"additional","affiliation":[{"name":"Division of Immunology & Allergy, Department of Pediatrics, Hospital for Sick Children, University of Toronto, Toronto, ON M5S 1A1, Canada"},{"name":"Canadian Centre for Primary Immunodeficiency, Hospital for Sick Children, University of Toronto, Toronto, ON M5S 1A1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chaim M.","family":"Roifman","sequence":"additional","affiliation":[{"name":"Division of Immunology & Allergy, Department of Pediatrics, Hospital for Sick Children, University of Toronto, Toronto, ON M5S 1A1, Canada"},{"name":"Canadian Centre for Primary Immunodeficiency, Hospital for Sick Children, University of Toronto, Toronto, ON M5S 1A1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,7,15]]},"reference":[{"key":"ref_1","unstructured":"Rich, R. 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