Mitochondrial stress markers associate with phenotypic variability in Fabry disease

Background Fabry disease (FD) exhibits marked clinical heterogeneity that cannot be fully explained by residual α-galactosidase A activity. Mitochondrial dysfunction has been reported in FD, but the role of mitochondrial stress remains unexplored. Objective To investigate whether mitochondrial unfolded protein response (mtUPR) related markers associate with phenotypic variability and correlates with disease severity. Methods We measured intracellular heat-shock protein 60 (Hsp60) expression by western blotting in fibroblasts and peripheral blood mononuclear cells (PBMCs). In the clinical cohort, intracellular Hsp60 was measured in PBMC whole-cell lysates from 27 FD patients (14 males, 13 females). Serum fibroblast growth-factor-21 and growth differentiation-factor-15 were measured in 35 patients. Clinical outcomes included Mainz Severity Score Index, Age-Adjusting Severity Score, estimated glomerular filtration rate, and left-ventricular mass index (LVMI). Results Hsp60 showed variability, with sex-specific associations. In males, higher Hsp60 correlated with lower LVMI (r 2 = −0.82, p = 0.01) and preserved renal function in late-onset patients (r 2 = 0.89, p = 0.006). In females, higher Hsp60 associated with higher LVMI (r 2 = 0.66, p = 0.045) and greater clinical severity. Male patients had elevated growth differentiation-factor-15 vs controls (935 vs 559 pg/ml, p = 0.002). Both mitokines correlated with age and disease severity. Conclusions mtUPR related markers exhibit sex- and genotype-specific patterns associated with disease severity, suggesting that mitochondrial stress contributes to phenotypic heterogeneity and support further longitudinal evaluation of Hsp60, FGF-21 and GDF-15 as candidate biomarkers of disease burden and treatment response.