Fabry disease is a rare X-linked hereditary disease caused by mutations in the AGAL gene encoding the lysosomal enzyme alpha-galactosidase A. Enzyme replacement therapy (ERT) is the current cornerstone of Fabry disease management. Involvement of kidney, heart and the central nervous system shortens life span, and fibrosis of these organs is a hallmark of the disease. Fibrosis was initially thought to result from tissue ischemia secondary to endothelial accumulation of glycosphingolipids in the microvasculature. However, despite ready clearance of endothelial deposits, ERT is less effective in patients who have already developed fibrosis. Several potential explanations of this clinical observation may impact on the future management of Fabry disease. Alternative molecular pathways linking glycosphingolipids and fibrosis may be operative; tissue injury may recruit secondary molecular mediators of fibrosis that are unresponsive to ERT, or fibrosis may represent irreversible tissue injury that limits the therapeutic response to ERT. We provide an overview of Fabry disease, with a focus on the assessment of fibrosis, the clinical consequences of fibrosis, and recent advances in understanding the cellular and molecular mechanisms of fibrosis that may suggest novel therapeutic approaches to Fabry disease.

Certain glomerulopathies are associated with increased levels of CD80 (B7-1). We measured the urinary excretion of CD80, podocyturia and proteinuria in controls and in subjects with Fabry disease either untreated or on enzyme replacement therapy (ERT). Cross-sectional study including 65 individuals: controls (n = 20) and Fabry patients (n = 45, 23 of them not on ERT and 22 on ERT). Variables included age, gender, urinary protein/creatinine ratio (UPCR), estimated glomerular filtration rate (eGFR), urinary uCD80/creatinine ratio (uCD80) and podocyturia. CD80 mRNA expression in response to lyso-Gb3, a bioactive glycolipid accumulated in Fabry disease, was studied in cultured human podocytes. Controls and Fabry patients did not differ in age, eGFR and gender. However, UPCR, uCD80 and podocyturia were significantly higher in Fabry patients than in controls. As expected, Fabry patients not on ERT were younger and a higher percentage were females. Non-ERT Fabry patients had less advanced kidney disease than ERT Fabry patients: UPCR was lower and eGFR higher, but uCD80 and podocyturia did not differ between non-ERT or ERT Fabry patients. There was a significant correlation between uCD80 and UPCR in the whole population (r 0.44, p 0.0005) and in Fabry patients (r 0.42, p 0.0046). Lyso-Gb3 at concentrations found in the circulation of Fabry patients increased uCD80 expression in cultured podocytes. Fabry disease is characterized by early occurrence of increased uCD80 excretion that appears to be a consequence of glycolipid accumulation. The potential for uCD80 excretion to reflect early, subclinical renal Fabry involvement should be further studied.

Fabry disease is an inherited metabolic disorder characterized by progressive lysosomal accumulation of glycolipids in a variety of cell types, including neural cells. Small, unmyelinated nerve fibers are particularly affected and small fiber peripheral neuropathy often clinically manifests at a young age. Neuropathic pain and pain attacks are often the presenting symptoms of the disease and start at an average age of 9 years in male patients and 16 years in female patients, but currently a systematic literature review in early childhood showed the presence of these symptoms before the age of 5 years. Clinical studies have shown that enzyme replacement therapy may improve the overall pain scores and pain intensity in patients; improvements in pain outcomes have been sustained during the long-term follow-up, allowing many patients to reduce their use of pain medication. Some indirect evidence from dose-switching studies suggests that enzyme replacement therapy dose may be of relevance to pain outcomes. Considering that damage to small nerve fibers occurs early, prompt treatment is important in order to limit damage to the peripheral nervous system. In this article a comprehensive overview of the existing literature on small nerve fiber pathophysiology and the relationship with neuropathic pain and treatment response in children and adults with Fabry disease is presented.

Introduction: Fabry disease is an X-linked recessive lysosomal storage disease; it is due to α-galactosidase A deficiency, and its clinical course shows repeated small artery strokes. Methods: Five patients diagnosed with Fabry disease (mean age ± SD = 28.2 ± 11.1 years) and 5 age-matched controls were evaluated with the following magnetic resonance image (MRI) sequences: T1, T2, FLAIR, diffusion, and single voxel spectroscopy at the parietal lobe. Results: Conventional images did not reveal alterations. Mean apparent diffusion coefficient (ADC) ± SD in the corona radiata of patients was 7.8 ± 0.2 × 10⁻⁴ mm²/s, which was significantly higher than for controls: 6.93 ± 0.49 × 10⁻⁴ mm²/s (P < 0.05). At the lenticular nucleus there were no differences in ADC values between patients (7.32 ± 0.2 × 10⁻⁴ mm²/s) and controls (7.2 ± 0.2 × 10⁻⁴ mm²/s). The mean ratio NAA/Cr ± SD at the parietal lobes was 1.94 ± 0.2 for patients and 2.1 ± 0.13 for controls (P = n.s.). Discussion: In a group of young Fabry disease patients with normal MRIs, a significant increment of over 12% in ADC values in the corona radiata was found compared with age-matched controls. The change could reflect increased interstitial water content after the Starling equilibrium under raised cerebral blood flow, which is a known feature of Fabry disease. Conclusion: Raised ADC values could predate conventional MRI changes in Fabry disease and therefore be a more sensitive marker of disease progression and response to enzymatic replacement therapy.

Fabry disease (FD) is a lysosomal storage disorder associated with marked cerebrovascular involvement. Conventional magnetic resonance imaging (MRI) shows different abnormalities, like white matter lesions that may already be present at an early stage in the disease. To present observations from a series of brain MRIs performed among a cohort of patients with FD and the relationship of imaging abnormalities with the presence of cardiovascular risk factors (CVRFs). A total of 70 patients with FD (43 women) were enrolled. The cardiac, renal, ophthalmic, and peripheral nerve functioning was assessed. The MRI evaluation included assessment for evidence of ischemia, microbleeds, pulvinar sign, Arnold-Chiari type 1 malformation, and vertebrobasilar dolichoectasia (VBD). The presence or absence of CVRFs was examined for all patients. Renal involvement was found in 60%, cardiac compromise in 30%, cornea verticillata in 91.4%, and acroparesthesias in 87.1% of patients. Brain MRI analysis found evidence of cerebral ischemic injury in 25.9% of men and 30.2% of women. Vertebrobasilar dolichoectasia was observed in imaging from 55.5% of men and 34.8% of women. The logistic regression analysis adjusted for cardiovascular risks factors, using ischemia or VBD as a dependent variable, showed no statistically significant results. Our results have demonstrated cerebrovascular involvement before the third decade in many patients with FD. This study is further evidence confirming that women are not just carriers of FD and should be followed clinically and evaluated comprehensively to monitor for disease burden and progression. Although silent brain ischemias in MRI should be included as a key feature for the diagnoses of FD, VBD is an earlier and frequent sign.