[A first pilot study on the neonatal screening of primary immunodeficiencies in Spain: TRECS and KRECS identify
P Olbrich1, B de Felipe1, C Delgado-Pecellin2
1Sección de Infectología e Inmunodeficiencias, Unidad de Pediatría, Hospital Virgen del Rocío, Sevilla, Instituto de Biomedicina de Sevilla (IBiS), Sevilla, España.
Insights
This study assessed T-cell receptor excision circles (TRECS) and kappa-deleting recombination excision circles (KRECS) in neonates to detect severe T and B-cell lymphopenia. The TRECS/KRECS assay shows promise for early diagnosis of primary immunodeficiencies.
Area of Science:
- Immunology
- Neonatal Screening
- Molecular Diagnostics
Background:
- Early diagnosis of primary immunodeficiencies like SCID and XLA is crucial for infant outcomes.
- TRECS and KRECS measurements can identify neonates with severe T or B-cell lymphopenia.
Purpose of the Study:
- To prospectively determine TRECS and KRECS levels in dried blood spot samples.
- To evaluate the efficacy of the TRECS/KRECS assay in identifying severe T and B-cell lymphopenia in neonates.
Main Methods:
- Multiplex PCR was used to determine TRECS and KRECS levels in neonatal blood samples.
- Defined PCR cut-off levels were used: TRECS<15 copies/μl, KRECS<10 copies/μl, ACTB>1000 copies/μl.
- Internal and external controls for SCID and XLA were included.
Main Results:
- 1068 neonates were analyzed; 1.87% of samples were insufficient, requiring resampling in 0.09%.
- Mean TRECS levels were 145 copies/μl, KRECS 82 copies/μl, and ACTB 2838 copies/μl.
- Lower cut-offs (TRECS<8, KRECS<4 copies/μl) correctly identified controls and yielded normal results for all samples.
Conclusions:
- This pilot study is the first in Spain to use the TRECS/KRECS/ACTB assay for identifying severe lymphopenias.
- The assay demonstrated applicability, but the ideal cut-off levels require further establishment for the Spanish population.
- Improvements in sample collection, storage, and preparation are recommended for enhanced assay performance.
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<10 copies/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 3238g (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.
