In this work, we used a reference population of newborns and sampled dried blood spots on Guthrie cards of 2,739 individual samples to determine the reference intervals for TRECs and KRECs values, in order to diagnose primary immunodeficiency by means of neonatal screening. The median absolute values for TRECs and KRECs were 195 (CI95%: 185-206) and 185 (CI95%: 176-197) copies per μl, respectively; the normalized value for TRECs was 2780 (CI95%: 2690-2840), and for KRECs, 2790 (CI95%: 2700-2900) copies per 2 × 105 copies of the albumin gene or 105 cells. The reference interval was calculated for 99 and 99.9 percentiles of total TRECs and KRECs individual values. Due to asymmetric distribution of data, the outliers were filtered off, using the Tukey’s criterion applied after logarithmic transformation of the data. When analyzing absolute values for TREC/KREC (per μL of blood), no “drop-down” TRECs values were identified; for KRECs, 18 experimental values were excluded from further analysis (from 9.8 to 13.5). The outlying values were not identified among the normalized values of TRECs/KRECs. The obtained reference values for TRECs and KRECs (at the 0.1 percentile level) were, respectively, 458 and 32 per 105 cells, or 23 and 17 per μl of blood samples from neonates.
- B cells
- Primary immunodeficiency (PID)
- Reference intervals
- T cells