Newborn Screening for SCID Identifies Patients with Ataxia Telangiectasia.
ABSTRACT PURPOSE: Severe combined immunodeficiency (SCID) is characterized by failure of T lymphocyte development and absent or very low T cell receptor excision circles (TRECs), DNA byproducts of T cell maturation. Newborn screening for TRECs to identify SCID is now performed in several states using PCR of DNA from universally collected dried blood spots (DBS). In addition to infants with typical SCID, TREC screening identifies infants with T lymphocytopenia who appear healthy and in whom a SCID diagnosis cannot be confirmed. Deep sequencing was employed to find causes of T lymphocytopenia in such infants. METHODS: Whole exome sequencing and analysis were performed in infants and their parents. Upon finding deleterious mutations in the ataxia telangiectasia mutated (ATM) gene, we confirmed the diagnosis of ataxia telangiectasia (AT) in two infants and then tested archival newborn DBS of additional AT patients for TREC copy number. RESULTS: Exome sequencing and analysis led to 2 unsuspected gene diagnoses of AT. Of 13 older AT patients for whom newborn DBS had been stored, 7 samples tested positive for SCID under the criteria of California's newborn screening program. AT children with low neonatal TRECs had low CD4 T cell counts subsequently detected (R = 0.64). CONCLUSIONS: T lymphocytopenia in newborns can be a feature of AT, as revealed by TREC screening and exome sequencing. Although there is no current cure for the progressive neurological impairment of AT, early detection permits avoidance of infectious complications, while providing information for families regarding reproductive recurrence risks and increased cancer risks in patients and carriers.
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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.Molecular Genetics and Metabolism Reports. 01/2014; 1:324–333.
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ABSTRACT: Introduction Early diagnosis of primary immunodeficiency such as severe combined immunodeficiency (SCID) and X-linked agammaglobulinemia (XLA) improves outcome of affected infants/children. The measurement of T-cell receptor excision circles (TRECS) and kappa-deleting recombination excision circles (KRECS) can identify neonates with severe T or B-cell lymphopenia. Objectives To determine TRECS and KRECS levels from prospectively collected dried blood spot samples (DBS) and to correctly identify severe T and B-cell lymphopenia. Material and methods Determination of TRECS and KRECS by multiplex PCR from neonates born in two tertiary hospitals in Seville between February 2014 and May 2014. PCR cut-off levels: TRECS<15 copies/μl, KRECS<10copies/μl, ACTB (β-actin)>1000 copies/μl. Internal (XLA, ataxia telangiectasia) and external (SCID) controls were included. Results A total of 1068 out of 1088 neonates (mean GA 39 weeks (38-40) and BW 3238 g (2930-3520) were enrolled in the study. Mean (median, min/max) copies/μl, were as follows: TRECS 145 (132, 8/503), KRECS 82 (71, 7/381), and ACTB 2838 (2763, 284/7710). Twenty samples (1.87%) were insufficient. Resampling was needed in one neonate (0.09%), subsequently giving a normal result. When using lower cut-offs (TRECS<8 and KRECS<4 copies/μl), all the samples tested were normal and the internal and external controls were correctly identified. Conclusion This is the first prospective pilot study in Spain using TRECS/KRECS/ACTB-assay, describing the experience and applicability of this method to identify severe lymphopenias. The ideal cut-off remains to be established in our population. Quality of sampling, storage and preparation need to be further improved.Anales de Pediatría 11/2014; · 0.72 Impact Factor
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ABSTRACT: IMPORTANCE: Newborn screening for severe combined immunodeficiency (SCID) using assays to detect T-cell receptor excision circles (TRECs) began in Wisconsin in 2008, and SCID was added to the national recommended uniform panel for newborn screened disorders in 2010. Currently 23 states, the District of Columbia, and the Navajo Nation conduct population-wide newborn screening for SCID. The incidence of SCID is estimated at 1 in 100,000 births. OBJECTIVES: To present data from a spectrum of SCID newborn screening programs, establish population-based incidence for SCID and other conditions with T-cell lymphopenia, and document early institution of effective treatments. DESIGN: Epidemiological and retrospective observational study. SETTING: Representatives in states conducting SCID newborn screening were invited to submit their SCID screening algorithms, test performance data, and deidentified clinical and laboratory information regarding infants screened and cases with nonnormal results. Infants born from the start of each participating program from January 2008 through the most recent evaluable date prior to July 2013 were included. Representatives from 10 states plus the Navajo Area Indian Health Service contributed data from 3,030,083 newborns screened with a TREC test. MAIN OUTCOMES AND MEASURES: Infants with SCID and other diagnoses of T-cell lymphopenia were classified. Incidence and, where possible, etiologies were determined. Interventions and survival were tracked. RESULTS: Screening detected 52 cases of typical SCID, leaky SCID, and Omenn syndrome, affecting 1 in 58,000 infants (95% CI, 1/46,000-1/80,000). Survival of SCID-affected infants through their diagnosis and immune reconstitution was 87% (45/52), 92% (45/49) for infants who received transplantation, enzyme replacement, and/or gene therapy. Additional interventions for SCID and non-SCID T-cell lymphopenia included immunoglobulin infusions, preventive antibiotics, and avoidance of live vaccines. Variations in definitions and follow-up practices influenced the rates of detection of non-SCID T-cell lymphopenia. CONCLUSIONS AND RELEVANCE: Newborn screening in 11 programs in the United States identified SCID in 1 in 58,000 infants, with high survival. The usefulness of detection of non-SCID T-cell lymphopenias by the same screening remains to be determined.JAMA. 08/2014; 312(7):729-38.