Biochemical and cellular abnormalities in presymptomatic pediatric patients with Fabry disease and Gaucher disease identified through newborn screening

Fabry disease (FD) and Gaucher disease (GD) are among the most prevalent lysosomal storage disorders, caused by deficiencies in the enzymes α-galactosidase A and glucocerebrosidase, respectively. These rare inherited metabolic diseases are characterized by the progressive accumulation of glycosphingolipids within lysosomes, leading to multisystemic manifestations and life-threatening complications. Early treatment is crucial to prevent irreversible organ damage, but diagnosis is often delayed due to the nonspecific nature of initial symptoms, which typically appear when significant damage has already occurred. Newborn screening (NBS) has emerged as a valuable approach for early diagnosis of these disorders, enabling timely intervention and potentially improved long-term outcomes. This study presents the largest European cohort of FD and GD patients identified through NBS and followed for ten years at a single clinical center, the University Hospital of Padua. From September 2015 to August 2025, 286,920 newborns were screened in the Northeast Italy region using a multiplexed tandem mass spectrometry assay, identifying 62 positive cases (40 FD, 22 GD). After comprehensive confirmatory biochemical and genetic testing, 35 patients were diagnosed (19 FD, 16 GD). Remarkably, the overall incidence was 1:7,779 for FD and 1:17,933 for GD, significantly higher than clinically estimated rates based on symptomatic cases, suggesting a high degree of underdiagnosis and highlighting the importance of NBS for these disorders. Longitudinal monitoring of plasma globotriaosylsphingosine (lysoGb3) and glucosylsphingosine (lysoGb1) levels, the substrates accumulating in FD and GD respectively, revealed their potential as early prognostic biomarkers. LysoGb3 levels effectively distinguished later-onset (LO) FD from variants of uncertain significance (VUS), while lysoGb1 levels predicted phenotypes in GD, discriminating non-neuronopathic from neuronopathic forms with remarkable accuracy. Monitoring biomarker trends during the first years of life further improved risk stratification and phenotype prediction capabilities. Remarkably, presymptomatic children with biochemically and genetically confirmed FD and GD exhibited elevated levels of inflammatory cytokines TNF-α and IL-1β, which correlated with the degree of substrate accumulation. Increased activation of the p38 mitogen-activated protein kinase (MAPK) pathway, a mediator of cellular stress responses, was also observed in these asymptomatic patients. Additionally, they displayed inhibition of the autophagy pathway, a crucial cellular process for lysosomal function and homeostasis, evidenced by reduced levels of the autophagosome marker LC3-II and upstream autophagy-related proteins. These findings suggest early dysregulation of inflammatory and cellular stress pathways, even before the onset of overt clinical manifestations. This study provides valuable insights into the natural history of FD and GD, highlighting the pivotal role of NBS in identifying affected individuals during the presymptomatic phase and the potential of biomarkers for early risk stratification and personalized management strategies. The ability to monitor disease progression from birth through childhood offers a unique opportunity to understand the initial pathogenic mechanisms and identify potential therapeutic targets. Notably, the observed dysregulation of inflammation and autophagy pathways suggests that interventions targeting these processes could interrupt or partially arrest the pathogenic cascades before the onset of overt clinical disease manifestations, potentially representing an alternative or complementary approach to the more invasive and costly enzyme replacement therapies.