To screen or not to screen G6PD deficiency in gNBS: insights from the BabyDetect pilot and current evidence.

As genomic newborn screening (gNBS) progresses toward broader implementation, questions arise regarding conditions to include on first-tier sequencing panels. Glucose-6-phosphate dehydrogenase (G6PD) deficiency, the most common monogenic disorder worldwide, is inconsistently screened in Europe despite its established role in neonatal hyperbilirubinemia and hemolytic crises. Using data from the Belgian BabyDetect pilot, one of the first European programs to include the evaluation of genomic and biochemical newborn screening in the same cohort, together with international evidence, we assessed the readiness of G6PD deficiency for inclusion in gNBS. In BabyDetect, genomic screening identified 94 newborns carrying pathogenic or likely pathogenic G6PD variants, including 17 neonates not detected by routine biochemical screening, demonstrating the complementary value of sequencing. However, identifying additional moderately deficient infants introduces uncertainty regarding penetrance, follow-up burden, healthcare impact and cost-effectiveness. Screening readiness was evaluated using an adapted NEXUS 2015 semi-quantitative framework, where G6PD deficiency scored 17/21, reflecting strong clinical benefit, high feasibility and ethical favorability, with moderate analytic validity, population impact, and evidence strength. Published economic modeling suggests the principal value of screening derives from reducing severe hyperbilirubinemia complications and later hemolytic crises, with additional benefits from improved pharmacovigilance and risk mitigation for subsequent siblings within affected families. Given the minimal marginal cost of adding G6PD to existing gNBS workflows, available evidence indicates that G6PD deficiency is well-suited for inclusion in gNBS when paired with confirmatory testing and proportionate, pediatric-led follow-up.