First 2-year experience of nationwide newborn screening for severe forms of T and B cell immunodeficiency: 2.3 million newborns analyzed using TREC and KREC in Russia

Importantly, early diagnosis through NBS allowed for the timely initiation of disease-specific treatments, including hematopoietic stem cell transplantation (HSCT), immunoglobulin replacement therapy, and targeted immunosuppressive or supportive care strategies. Early intervention may reduce the risk of severe infections, improve neurodevelopmental outcomes, and prevent irreversible organ damage or malignancies in predisposed syndromes. Overall, our study demonstrates the effectiveness of large-scale implementation of TREC/KREC-based NBS in identifying a broad spectrum of immunodeficiencies and highlights future directions for improving NBS algorithms, follow-up protocols, and individualized medical management for affected infants.