Aggeliki Kolialexi

Newborn screening for inborn errors of immunity and spinal muscular atrophy (SMA) enables early identification of infants at risk for severe disorders, facilitating timely treatment and improved outcomes. This study describes the first Greek experience with combined screening for SMA and severe T- and B-cell lymphopenias using SMN1 exon 7 analysis and T-cell receptor excision circles (TREC)/kappa-deleting recombination excision circles (KREC) measurements, using a single dried blood spot (DBS) sample. In 2026, 29,460 newborns were screened using a commercially available in vitro diagnostic kit. TREC and KREC were assessed semi-quantitatively, while SMA screening was based on qualitative detection of the SMN1 exon 7 target. Of these, 2168 (7.36%) required duplicate retesting, with 481 requiring a second DBS sample. Among the 481 newborns for whom a second DBS card was requested, 469 cards were received. Of these, 446 were classified as negative, 13 remained inconclusive, 4 were referred for genetic/immunological confirmatory evaluation, 2 remained under immunological follow-up, and 4 demonstrated recovery on repeat testing. Confirmatory evaluation identified four clinically significant cases: two with SMA, one with severe T-cell lymphopenia associated with 22q11.2 deletion syndrome, and one with CHARGE syndrome. Several low TREC/KREC results normalized on repeat testing. This experience demonstrates the feasibility of combined screening and highlights the importance of appropriate follow-up and confirmatory evaluation.

Background/Objectives: Scalable molecular workflows may facilitate carrier screening for spinal muscular atrophy (SMA) and cystic fibrosis (CF). This study aimed to develop and validate a dried blood spot (DBS)-based multiplex digital PCR (dPCR) workflow for SMN1 and SMN2 copy-number analysis and targeted detection of CFTR p.Phe508del. Methods: The workflow combined direct DNA elution with multiplex dPCR. Analytical validation used 50 previously characterized samples, with multiplex ligation-dependent probe amplification (MLPA) and Sanger sequencing as reference methods. The workflow was subsequently applied to 1670 women from Crete and Ikaria, Greece, followed by targeted testing of 10 partners. Results: All 50 directly eluted samples amplified successfully. dPCR showed complete agreement with reference methods. Repeatability coefficients of variation were below 5%. Copy-number classification performance estimates are apparent, as thresholds were derived and evaluated in the same small validation cohort. Among 1670 women screened, 34 (2.04%) were identified as SMN1 carriers and 20 (1.20%) as CFTR p.Phe508del carriers. Partner testing identified two carrier couples. Conclusions: The DBS-based multiplex dPCR workflow demonstrated complete analytical concordance with reference methods in this preliminary validation and was implemented in a population screening cohort. Its targeted scope leaves residual carrier risk, requiring appropriate counseling. Larger independent validation and formal throughput and cost assessments are needed before routine implementation.

Newborn screening for primary immunodeficiencies and spinal muscular atrophy (SMA) enables early identification of infants at risk for severe disorders, facilitating timely treatment and improved outcomes. This study describes the first Greek experience with combined screening for T-cell receptor excision circles (TREC), kappa-deleting recombination excision circles (KREC), and SMN1 using a single dried blood spot (DBS) sample. During 2026, 29.460 newborns were screened using a commercially available in vitro diagnostic kit. TREC and KREC were assessed semi-quantitatively, while SMA screening was based on qualitative detection of the SMN1 exon 7 target. Of these, 2.168 (7,36%) required duplicate retesting, with 481 requiring a second DBS sample. Among the 481 newborns for whom a second DBS card was requested, 469 cards were received. Of these, 446 were classified as negative, 13 remained inconclusive, 4 were referred for genetic/immunological confirmatory evaluation, 2 remained under immunological follow-up, and 4 demonstrated recovery on repeat testing. Confirmatory evaluation identified four clinically significant cases: two with SMA, one with severe T-cell lymphopenia associated with 22q11.2 deletion syndrome, and one with CHARGE syndrome. Several low TREC/KREC results normalized on repeat testing. This experience demonstrates the feasibility of combined screening and highlights the importance of appropriate follow-up and confirmatory evaluation.

We present a neonatal case of Wiedemann–Steiner syndrome (WSS) with a de novo, previously reported KMT2A missense variant (c.3464G>A; p.Cys1155Tyr; NM_001197104.2), and provide a focused literature review of this specific variant. WSS (OMIM#605130) is a rare neurodevelopmental disorder caused by heterozygous variants in the KMT2A gene, which encodes a histone H3 lysine K4 (H3K4) methyltransferase involved in transcriptional regulation. Clinically, the syndrome is characterized by developmental delay, distinctive facial features, short stature, hypertrichosis, and neurological manifestations such as hypotonia and seizures. In this single-patient report, we describe additional clinical findings, including interstitial lung disease and hypertrophic pyloric stenosis requiring surgical intervention. These may represent rare manifestations of WSS that require confirmation in further reports before a formal expansion of the phenotypic spectrum can be established. Most pathogenic KMT2A variants arise de novo and are typically nonsense or frameshift; however, missense variants have also been reported and may have complex functional consequences. Haploinsufficiency is considered the primary pathogenic mechanism, leading to the disruption of chromatin modification and transcriptional regulation. While emerging genotype–phenotype correlations are being identified, considerable variability remains. Given the single-patient nature of this study, these observations should be considered hypothesis-generating and require confirmation in additional cases.