title: The TREC/KREC assay for the diagnosis and monitoring of patients with DiGeorge syndrome.
abstract: DiGeorge syndrome (DGS) presents with a wide spectrum of thymic pathologies. Nationwide neonatal screening programs of lymphocyte production using T-cell recombination excision circles (TREC) have repeatedly identified patients with DGS. We tested what proportion of DGS patients could be identified at birth by combined TREC and kappa-deleting element recombination circle (KREC) screening. Furthermore, we followed TREC/KREC levels in peripheral blood (PB) to monitor postnatal changes in lymphocyte production.
  
  
  METHODS
  TREC/KREC copies were assessed by quantitative PCR (qPCR) and were related to the albumin control gene in dry blood spots (DBSs) from control (n = 56), severe immunodeficiency syndrome (SCID, n = 10) and DGS (n = 13) newborns. PB was evaluated in DGS children (n = 32), in diagnostic samples from SCID babies (n = 5) and in 91 controls.
  
  
  RESULTS
  All but one DGS patient had TREC levels in the normal range at birth, albeit quantitative TREC values were significantly lower in the DGS cohort. One patient had slightly reduced KREC at birth. Postnatal DGS samples revealed reduced TREC numbers in 5 of 32 (16%) patients, whereas KREC copy numbers were similar to controls. Both TREC and KREC levels showed a more pronounced decrease with age in DGS patients than in controls (p < 0.0001 for both in a linear model). DGS patients had higher percentages of NK cells at the expense of T cells (p < 0.0001). The patients with reduced TREC levels had repeated infections in infancy and developed allergy and/or autoimmunity, but they were not strikingly different from other patients. In 12 DGS patients with paired DBS and blood samples, the TREC/KREC levels were mostly stable or increased and showed similar kinetics in respective patients.
  
  
  CONCLUSIONS
  The combined TREC/KREC approach with correction via control gene identified 1 of 13 (8%) of DiGeorge syndrome patients at birth in our cohort. The majority of patients had TREC/KREC levels in the normal range.
authors.affiliation: CLIP, Department of Paediatric Haematology/Oncology, 2nd Medical School, Charles University Prague and University Hospital Motol, Prague, Czech Republic.
authors.forename: Eva
authors.initials: E
authors.lastname: Froňková
authors.affiliation: Department of Immunology, 2nd Medical School, Charles University Prague and University Hospital Motol, Prague, Czech Republic.
authors.forename: Adam
authors.initials: A
authors.lastname: Klocperk
authors.affiliation: CLIP, Department of Paediatric Haematology/Oncology, 2nd Medical School, Charles University Prague and University Hospital Motol, Prague, Czech Republic.
authors.forename: Michael
authors.initials: M
authors.lastname: Svatoň
authors.affiliation: CLIP, Department of Paediatric Haematology/Oncology, 2nd Medical School, Charles University Prague and University Hospital Motol, Prague, Czech Republic.
authors.forename: Michaela
authors.initials: M
authors.lastname: Nováková
authors.affiliation: CLIP, Department of Paediatric Haematology/Oncology, 2nd Medical School, Charles University Prague and University Hospital Motol, Prague, Czech Republic.
authors.forename: Michaela
authors.initials: M
authors.lastname: Kotrová
authors.affiliation: Department of Immunology, 2nd Medical School, Charles University Prague and University Hospital Motol, Prague, Czech Republic.
authors.forename: Jana
authors.initials: J
authors.lastname: Kayserová
authors.affiliation: CLIP, Department of Paediatric Haematology/Oncology, 2nd Medical School, Charles University Prague and University Hospital Motol, Prague, Czech Republic.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Kalina
authors.affiliation: CLIP, Department of Paediatric Haematology/Oncology, 2nd Medical School, Charles University Prague and University Hospital Motol, Prague, Czech Republic.
authors.forename: Petra
authors.initials: P
authors.lastname: Keslová
authors.affiliation: Department of Pediatrics, 3rd Medical School, Charles University Prague and University Hospital Kralovske Vinohrady, Prague, Czech Republic.
authors.forename: Felix
authors.initials: F
authors.lastname: Votava
authors.affiliation: Department of Clinical Biochemistry, Children Hospital, Faculty of Medicine, Masaryk University Brno, Brno, Czech Republic.
authors.forename: Hana
authors.initials: H
authors.lastname: Vinohradská
authors.affiliation: Department of Clinical Immunology and Allergology, Medical Faculty, and Central European Institute of Technology, Masaryk University, Brno, Czech Republic; Molecular Genetics Lab, Centre for Cardiovascular Surgery and Transplantation, Brno, Czech Republic.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Freiberger
authors.affiliation: CLIP, Department of Paediatric Haematology/Oncology, 2nd Medical School, Charles University Prague and University Hospital Motol, Prague, Czech Republic.
authors.forename: Ester
authors.initials: E
authors.lastname: Mejstříková
authors.affiliation: CLIP, Department of Paediatric Haematology/Oncology, 2nd Medical School, Charles University Prague and University Hospital Motol, Prague, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Trka
authors.affiliation: Department of Immunology, 2nd Medical School, Charles University Prague and University Hospital Motol, Prague, Czech Republic.
authors.forename: Anna
authors.initials: A
authors.lastname: Sedivá
mesh_terms: D000293:Adolescent; D001681:Biological Assay; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D004270:DNA, Circular / Q000235:genetics*; D004062:DiGeorge Syndrome / Q000175:diagnosis* / Q000235:genetics / Q000276:immunology; D005260:Female; D006801:Humans; D007153:Immunologic Deficiency Syndromes / Q000175:diagnosis* / Q000235:genetics / Q000276:immunology; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D015997:Neonatal Screening; D060888:Real-Time Polymerase Chain Reaction; D016511:Severe Combined Immunodeficiency / Q000175:diagnosis* / Q000235:genetics / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D004270:DNA, Circular