Sex-Based Disparities in Fabry Disease Cause Challenges in Newborn Screening

INTRODUCTION: Fabry disease (FD) is a multi-systemic, X-linked lysosomal storage disorder caused by decreased α-galactosidase activity. Early diagnosis enables timely treatment, but enzyme-based newborn screening (NBS) may not detect affected females. We hypothesized that enzyme-based NBS limitations contribute to sex-based diagnostic disparities in FD and investigated these differences. METHODS: Retrospective cohort analyses used data from the Fabry Registry (FR: 2001-2023) and Tennessee NBS (2017-2024). Sex differences in diagnosis via NBS, biochemical phenotype, symptom onset, and treatment initiation were analyzed using Wilcoxon and Chi-square tests. RESULTS: Among 8,657 FR individuals, 73 (67 males, six females) were identified via NBS. FR data show that affected females had significantly higher residual α-galactosidase activity than affected males (leukocyte median: 45.9% vs. 3.9%, plasma median: 32.5% vs. 3.9%; p<0.0001 for both). FR females had delayed symptom onset (18.1 vs. 11.1 years), later diagnosis (35.5 vs. 30.8 years), and lower treatment rates (51.1% vs. 80.8%) compared to males (all %; p<0.0001). Tennessee NBS detected 25 males but no females. CONCLUSION: Females with FD have delays in symptom onset, diagnosis and treatment compared to males. Furthermore, higher residual enzyme activity causes current enzyme-based NBS to miss most females. Incorporating sex-specific cutoffs and/or molecular sequencing into NBS could improve early detection and reduce sex-based disparities.