Newborn Screening for Primary T- and B-Cell Immune Deficiencies—A Prospective Study in Andalucía

Abstract

Background: Quantification of T-cell-receptor-excision circles (TRECs) and kappa-deletingrecombination-excision circles (KRECs) from dried blood spots (DBS) allows detection of neonates with severe T-cell and/or B-cell lymphopenia that are potentially affected by severe combined immunodeficiency (SCID), as well as X-linked agammaglobulinemia (XLA). Methods: Determination of TRECs and KRECs using a triplex RT-PCR (TRECS-KRECS-β-actin) assay from prospectively collected DBS between February 2014 and December 2016 in three hospitals in Seville, Spain. Cutoff levels were TRECs < 6/punch, KRECs < 4/punch and b-actin > 700/punch. Internal (SCID, XLA, ataxia telangiectasia) and external controls (CDC) were included. Results: A total of 8943 DBS samples obtained from 8814 neonates were analysed. Re-punching was necessary in 124 samples (1.4%) due to insufficient β-actin values (<700 copies/punch). Preterm neonates (GA < 37 weeks) and neonates with a BW < 2500 g showed significantly lower TRECs and KRECs levels (p < 0.001). Due to repeated pathological results, ten neonates were re-sampled (0.11%), of which five neonates (0.055%) confirmed the pathological results: one case was a fatal chromosomopathy (TRECs 1/KRECs 4); two were extreme premature newborns (TRECs 0/KRECs 0 and TRECs 1/KRECs 20 copies/punch); and 2 neonates were born to mothers receiving azathioprine during pregnancy (TRECs 92/KRECs 1 and TRECs 154/KRECs 3 copies/punch). All controls were correctly identified. Conclusions: Severe T-and B-cell lymphopenias were correctly identified by the TRECS-KRECS-β-actin assay. Prematurity and low BW are associated with lower TREC and KREC levels. Extreme prematurity and maternal immune suppressive therapy can cause false positive results of TRECs and KRECs values.

Implementation of TREC/KREC detection protocol for newborn SCID screening in Bulgaria: a pilot study

“…These differences are probably due to the different methods used for KREC quantification – RT-PCR vs. the commercial EnLite Neonatal TREC-KREC kit. No statistically significant differences were reported for KREC in regard to gestational age and weight at birth, unlike the findings in previous studies [ 27 , 28 ]. Since we have tested for KREC a relatively small sample number, no conclusions for the whole population should be made.…”

“…SPOT-it), the obtained values of TREC were found to be similar to TRECs reported in other publications. Median TREC for the entire studied population was 87 copies/µl, compared to 86 copies/µl in Andalusia and the Polish-German transborder area [ 27 , 28 ], 93 copies/µl in Seville [ 11 ] and 96 copies/µl in the Dutch population [ 25 ]. Associations of TREC levels with the demographic variables gestational age, birth weight and gender were also found in previous studies in Spain and Israel [ 11 , 14 , 27 ].…”

“…Median TREC for the entire studied population was 87 copies/µl, compared to 86 copies/µl in Andalusia and the Polish-German transborder area [ 27 , 28 ], 93 copies/µl in Seville [ 11 ] and 96 copies/µl in the Dutch population [ 25 ]. Associations of TREC levels with the demographic variables gestational age, birth weight and gender were also found in previous studies in Spain and Israel [ 11 , 14 , 27 ]. The median TREC value for preterm babies was 76 copies/µl compared to 88 copies/µl in full-term babies ( p < 0.05).…”

Recommendations for uniform definitions used in newborn screening for severe combined immunodeficiency

“…After screening abstracts and titles, 38 articles were included in the qualitive analysis (Fig 1). Four overview articles, [16][17][18][19] 11 population-based studies, [20][21][22][23][24][25][26][27][28][29][30] 20 pilot studies, [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] and 3 studies including both pilot and population data [51][52][53] were included. The number of screened newborns ranged from 141 in Korea 37 to 3,252,156 in California, 22 with varying referral and retest rates between screening programs.…”

Second-Tier Next Generation Sequencing Integrated in Nationwide Newborn Screening Provides Rapid Molecular Diagnostics of Severe Combined Immunodeficiency

“…In Europe, universal SCID screening started in the region of Catalonia in Spain (Jan 2017) ( 8 ), Iceland (2017), Switzerland (Jan 2019), Sweden and Germany (Aug 2019) proceeded by pilots ( 9 – 11 ) 3 , and Denmark (Feb 2020) ( 12 ). And hospital pilots have been performed ( 13 ), or are ongoing in European countries and regions such as France ( 14 ), Finland, Poland, Italy, and the Netherlands ( 15 , 16 ).…”