Fabry disease (FD) is a rare genetic disorder caused by a deficiency in the α-galactosidase A enzyme, which results in the globotriaosylceramide accumulation in many organs, including the kidneys. Nephropathy is a major FD complication that can progress to end-stage renal disease if not treated early. Although enzyme replacement therapy and chaperone therapy are effective, other treatments such as ACE inhibitors and angiotensin receptor blockers can also provide nephroprotective effects when renal damage is also established. Recently, SGLT2 inhibitors have been approved as innovative drugs for treating chronic kidney disease. Thus, we plan a multicenter observational prospective cohort study to assess the effect of Dapagliflozin, a SGLT2 inhibitor, in FD patients with chronic kidney disease (CKD) stages 1–3. The objectives are to evaluate the effect of Dapagliflozin primarily on albuminuria and secondarily on kidney disease progression and clinical FD stability. Thirdly, any association between SGT2i and cardiac pathology, exercise capacity, kidney and inflammatory biomarkers, quality of life, and psychosocial factors will also be evaluated. The inclusion criteria are age ≥ 18; CKD stages 1–3; and albuminuria despite stable treatment with ERT/Migalastat and ACEi/ARB. The exclusion criteria are immunosuppressive therapy, type 1 diabetes, eGFR < 30 mL/min/1.73 m², and recurrent UTIs. Baseline, 12-month, and 24-month visits will be scheduled to collect demographic, clinical, biochemical, and urinary data. Additionally, an exercise capacity and psychosocial assessment will be performed. The study could provide new insights into using SGLT2 inhibitors for treating kidney manifestations in Fabry disease.

Inherited metabolic diseases (IMDs) are genetic conditions that result in metabolism alterations. Although research-based Next Generation Sequencing (NGS) testing for IMD has been recently implemented, its application in a clinical diagnostic setting remains challenging. Thus, we aimed at investigating the genetic diagnostic approach in a cohort of adult patients with IMDs referred to our adult metabolic unit. A retrospective analysis was performed collecting demographic, clinical, and genetic data of patients referred to the Adult Metabolic Unit in Padua from November 2017 to March 2022. In total, 108 adult patients (mean age: 33 years ± 17, 55% women) were enrolled in the study, and 83 (77%) of the patients transitioned from the pediatric metabolic clinics. The most prevalent groups of IMDs were disorders of complex molecule degradation (32 patients) and disorders of amino acid metabolism (31) followed by disorders of carbohydrates (26). Molecular genetic diagnosis was reported by 69 (64%) patients, with the higher rate reported by patients referred from specialty other than pediatric (88% vs. 55%). Almost all the subjects (92%) with disorders of complex molecule degradation had a genetic diagnosis. Patients with disorders of amino acid metabolism and disorders of carbohydrates had almost the same rate of genetic test (39% and 38%, respectively). Among the patients without a genetic diagnosis that we tested, two novel mutations in disease-associated genes were detected. In our single-center cohort, a consistent proportion (36%) of subjects with IMDs reaches the adulthood without a genetic demonstration of the disease. This lack, even if in some cases could be related to disease-specific diagnostic approach or to different disease onset, could be detrimental to patient management and impact to some of the specific needs of adult subjects.

Glycogen storage diseases (GSDs) represent a model of pathological accumulation of glycogen disease in the kidney that, in animal models, results in nephropathy due to abnormal autophagy and mitochondrial function. Patients with Glycogen Storage Disease 1a (GSD1a) accumulate glycogen in the kidneys and suffer a disease resembling diabetic nephropathy that can progress to renal failure. In this study, we addressed whether urine-derived epithelial cells (URECs) from patients with GSD1a maintain their biological features, and whether they can be used as a model to study the renal and metabolic phenotypes of this genetic condition. Studies were performed on cells extracted from urine samples of GSD1a and healthy subjects. URECs were characterized after the fourth passage by transmission electron microscopy and immunofluorescence. Reactive oxygen species (ROS), at different glucose concentrations, were measured by fluorescent staining. We cultured URECs from three patients with GSD1a and three healthy controls. At the fourth passage, URECs from GSD1a patients maintained their massive glycogen content. GSD1a and control cells showed the ciliary structures of renal tubular epithelium and the expression of epithelial (E-cadherin) and renal tubular cells (aquaporin 1 and 2) markers. Moreover, URECs from both groups responded to changes in glucose concentrations by modulating ROS levels. GSD1a cells were featured by a specific response to the low glucose stimulus, which is the condition that more resembles the metabolic derangement of patients with GSD1a. Through this study, we demonstrated that URECs might represent a promising experimental model to study the molecular mechanisms leading to renal damage in GSD1a, due to pathological glycogen storage.

Fabry disease (FD) is an X-linked lysosome storage disease that results in the accumulation of globotriaosylceramide (Gb3) throughout the body leading to irreversible target organ damage. As the role of secondary mediators (inflammatory molecules) and their mechanisms has not been fully elucidated, we focused on the interleukin (IL)-6 system in adult FD patients and in matched healthy subjects. To obtain insights into the complex regulation of IL-6 actions, we used a novel approach that integrates information from plasma and exosomes of FD patients (n = 20) and of healthy controls (n = 15). Soluble IL-6 receptor (sIL-6R) levels were measured in plasma with the ELISA method, and membrane-bound IL-6R was quantified in plasma and urinary exosomes using flow cytometry. In FD patients, the levels of soluble IL-6R in plasma were higher than in control subjects (28.0 ± 5.4 ng/mL vs. 18.9 ± 5.4 ng/mL, p < 0.0001); they were also higher in FD subjects with the classical form as compared to those with the late-onset form of the disease (36.0 ± 11.4 ng/mL vs. 26.1 ± 4.5 ng/mL, p < 0.0001). The percentage of urinary exosomes positive for IL-6R was slightly lower in FD (97 ± 1 vs. 100 ± 0% of events positive for IL-6R, p < 0.05); plasma IL-6 levels were not increased. These results suggest a potential role of IL-6 in triggering the inflammatory response in FD. As in FD patients only the levels of sIL-6Rs are consistently higher than in healthy controls, the IL-6 pathogenic signal seems to prevail over the homeostatic one, suggesting a potential mechanism causing multi-systemic damage in FD.

The increasing use of next-generation sequencing (NGS), including multigene panels and exome and genome sequencing, has led to increased identification of rare and previously unreported variants in Mendelian disorders, though evidence supporting their clinical interpretation remains limited. In Fabry disease (FD), this issue is particularly relevant because the interpretation of individual GLA gene variants contributes to establishing whether a variant supports the diagnosis, with an impact on treatment decisions. In fact, FD is characterized by a phenotypic heterogeneity depending on patients’ biological sex and the underlying GLA variant. This represents the main reason why integrating genetic data with phenotypic expression is challenging, and defining the pathogenic role of novel variants remains complex. Early discrimination between pathogenic and non-pathogenic GLA variants is essential. However, variant classification, a definitive diagnosis of FD, and the decision to start disease-specific treatment are separate steps. A variant of uncertain significance (VUS), an isolated biochemical abnormality or non-specific organ involvement, is not in itself sufficient to establish the diagnosis or justify enzyme replacement or chaperone therapy. In fact, the most severe cases of FD have a significantly compromised quality of life up to reduced life expectancy, especially with regard to cardiac and renal complications. In recent years, some GLA variants have been reclassified following investigation and clinical observations by multidisciplinary working groups, making it possible to better define if they are pathogenic or not. Regardless of the clinical scenario leading to the identification of a novel GLA variant (i.e., family screening, neonatal screening, clinical profile suggestive of FD, incidental finding), any genetic finding becomes relevant when it is complemented by laboratory, clinical and instrumental investigations that require a concerted effort among the many health care professionals involved in the diagnostic process. The present work summarizes the outcomes of a series of expert meetings with the aim to provide some shared and practical indications for managing the genetic report of a novel GLA variant in order to promptly start the most suitable diagnostic journey and assess corresponding phenotype and clinical characterization.

Increasingly sophisticated genetic panels have disproportionately increased the identification rate of novel gene variants in Mendelian conditions. In Fabry disease (FD), this phenomenon is particularly relevant because the pathogenicity of individual gene variants has an impact on treatment proposal. In fact, FD is characterized by a phenotypical heterogeneity depending on patients' biological sex and the underlying GLA mutation. This represents the main reason why integrating genetic data with phenotypic expression is challenging, and defining the pathogenic role of novel variants remains complex. The early discrimination between pathogenic and non-pathogenic GLA variants is crucial to enable timely initiation of treatments such as Enzyme Replacement Therapy (ERT), which has been shown to significantly slow down the progression of the disease. In fact, the most severe cases of FD have a significantly compromised quality of life up to reduced life expectancy, especially with regard to cardiac and renal complications. In recent years, some GLA variants have been reclassified following investigation and clinical observations by multidisciplinary working groups that have made it possible to better define if they are pathogenic or not. Regardless of the clinical scenario leading to the identification of a novel GLA variant (i.e., family screening, neonatal screening, clinical profile suggestive of FD, incidental finding), any genetic finding becomes relevant when it is complemented by laboratory, clinical and instrumental investigations that require a concerted effort among the many health care professionals involved in the diagnostic process. The present work summarizes the outcomes of a series of expert meetings with the aim to provide some shared and practical indications for managing the genetic report of a novel GLA variant so to promptly start the most suitable diagnostic journey and assess corresponding phenotype and clinical characterization.