BACKGROUND: Severe combined immunodeficiency (SCID) is a fatal but treatable inborn error of immunity (IEI). Newborn screening (NBS) using T-cell receptor excision circles (TREC) has been adopted globally, with very few countries incorporating kappa recombination excision circles (KREC) to also detect early B-cell development disorders, such as X-linked agammaglobulinemia (XLA). OBJECTIVE: To evaluate the effectiveness of a 2-year pilot SCID NBS program in the Czech Republic, emphasising the utility of combined TREC/KREC screening. METHODS: Between January 2022 and December 2023, a dual TREC/KREC NBS pilot was conducted across the Czech Republic, alongside spinal muscular atrophy (SMA) screening. Approximately 200,000 newborns were screened using quantitative real-time PCR on dried blood spots collected 48-72 h after birth. RESULTS: The pilot referred 58 newborns, identifying 21 cases of IEI, including two SCID cases, with an overall incidence of TREC/KREC screenable IEI of 10.5/100,000 newborns. SCID incidence was 1/100,000. KREC screening proved invaluable, detecting 10 cases of congenital agammaglobulinemia including novel non-XLA forms, which increased the estimated incidence of agammaglobulinemia in the Czech Republic sixfold. Over one-third of low KREC results were linked to maternal immunosuppression. CONCLUSION: The Czech pilot demonstrated the effectiveness of integrated TREC/KREC NBS in detecting both T- and B-cell immunodeficiencies. As of 2024, SCID and SMA screening are included in the nationwide NBS, with KREC screening significantly improving early detection of B-cell disorders.

• Klíčová slova
• IGLL1, KREC, SCID, TREC, XLA, agammaglobulinemia, dried blood spot, screening, severe combined immunodeficiency,
• MeSH
• agamaglobulinemie diagnóza   MeSH
• B-lymfocyty imunologie   MeSH
• genetické nemoci vázané na chromozom X MeSH
• lidé MeSH
• novorozenec MeSH
• novorozenecký screening * metody   MeSH
• pilotní projekty MeSH
• receptory antigenů T-buněk * genetika   MeSH
• těžká kombinovaná imunodeficience * diagnóza   genetika   epidemiologie   MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• novorozenec MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika epidemiologie   MeSH
• Názvy látek
• receptory antigenů T-buněk * MeSH