Antiproteinuric therapy and fabry nephropathy: sustained reduction of proteinuria in patients receiving enzyme replacement therapy with agalsidase-beta

Cardiac manifestations of Fabry disease in G3Stg/GlaKO and GlaKO mouse models-Translation to Fabry disease patients

Fabry disease (FD) is an X-linked disorder of glycosphingolipid metabolism caused by mutations in the GLA gene encoding alpha-galactosidase A (α-Gal). Loss of α-Gal activity leads to progressive lysosomal accumulation of α-Gal substrate, predominately globotriaosylceramide (Gb3) and its deacylated derivative globotriaosylsphingosine (lyso-Gb3). FD manifestations include early onset neuropathic pain, gastrointestinal symptoms, and later onset life-threatening renal, cardiovascular and cerebrovascular disorders. Current treatments can preserve kidney function but are not very effective in preventing progression of cardiovascular pathology which remains the most common cause of premature death in FD patients. There is a significant need for a translational model that could be used for testing cardiac efficacy of new drugs. Two mouse models of FD have been developed. The α-Gal A-knockout (GlaKO) model is characterized by progressive tissue accumulation of Gb3 and lyso-Gb3 but does not develop any Fabry pathology besides mild peripheral neuropathy. Reports of minor cardiac function abnormalities in GlaKO model are inconsistent between different studies. Recently, G3Stg/GlaKO was generated by crossbreeding GlaKO with transgenic mice expressing human Gb3 synthase. G3Stg/GlaKO demonstrate higher tissue substrate accumulation and develop cellular and tissue pathologies. Functional renal pathology analogous to that found in early stages of FD has also been described in this model. The objective of this study is to characterize cardiac phenotype in GlaKO and G3Stg/GlaKO mice using echocardiography. Longitudinal assessments of cardiac wall thickness, mass and function were performed in GlaKO and wild-type (WT) littermate controls from 5-13 months of age. G3Stg/GlaKO and WT mice were assessed between 27-28 weeks of age due to their shortened lifespan. Several cardiomyopathy characteristics of early Fabry pathology were found in GlaKO mice, including mild cardiomegaly [up-to-25% increase in left ventricular (LV mass)] with no significant LV wall thickening. The LV internal diameter was significantly wider (up-to-24% increase at 9-months), when compared to the age-matched WT. In addition, there were significant increases in the end-systolic, end-diastolic volumes and stroke volume, suggesting volume overload. Significant reduction in Global longitudinal strain (GLS) measuring local myofiber contractility of the LV was also detected at 13-months. Similar GLS reduction was also reported in FD patients. Parameters such as ejection fraction, fractional shortening and cardiac output were either only slightly affected or were not different from controls. On the other hand, some of the cardiac findings in G3Stg/GlaKO mice were inconsistent with Fabry cardiomyopathy seen in FD patients. This could be potentially an artifact of the Gb3 synthase overexpression under a strong ubiquitous promoter. In conclusion, GlaKO mouse model presents mild cardiomegaly, mild cardiac dysfunction, but significant cardiac volume overload and functional changes in GLS that can be used as translational biomarkers to determine cardiac efficacy of novel treatment modalities. The level of tissue Gb3 accumulation in G3Stg/GlaKO mouse more closely recapitulates the level of substrate accumulation in FD patients and may provide better translatability of the efficacy of new therapeutics in clearing pathological substrates from cardiac tissues. But interpretation of the effect of treatment on cardiac structure and function in this model should be approached with caution.

Fabry disease: a rare disorder calling for personalized medicine

Fabry Disease (FD) is a genetic disease caused by a deficiency in the activity of lysosomal galactosidase A (α-GalA), an enzyme responsible for the catabolism of globotriaosylceramide (Gb3). Since lysosomes are present throughout the body and play a crucial role in catabolism and recycling of cytosolic compounds, FD can affect multiple organs and result in various symptoms, including renal, cardiovascular, neurological, cutaneous, and ophthalmic manifestations. Due to the nonspecific symptoms and the rarity of FD, it is often diagnosed late in life. However, introducing targeted therapies such as enzyme replacement therapy (ERT) and chaperone therapy has significantly improved FD's natural history and prognosis by restoring α-GalA enzyme activity. Despite the advancements, there are limitations to the currently available therapies, which has prompted research into new potential treatments for FD, including alternative forms of enzyme replacement therapy, substrate reduction therapy, mRNA therapy, and genetic therapy. In this review, we analyze the epidemiology, pathophysiology, and treatment of FD, with particular emphasis on promising therapeutic opportunities that could shift the treatment of this rare disease from a standardized to a personalized approach soon.

Is just enzyme replacement therapy enough for Fabry disease treatment? Have we missed a trick?

BACKGROUND AND AIM

In Fabry disease (FD), primary factors such as glycosphingolipid deposition that initiate kidney damage and secondary factors that advance kidney damage to fibrosis are different. Periostin is a molecule of proven importance in renal inflammation and fibrosis. It was previously shown that periostin plays an essential role in the process leading to renal fibrosis and its expression is increased in many kidney diseases. In the present study, we aimed to reveal the relationship between periostin and Fabry nephropathy.

MATERIAL-METHOD

This cross-sectional study included 18 FD patients (10 males, 8 females) with enzyme replacement therapy (ERT) indications and 22 healthy control patients of similar age and gender. At the time of diagnosis, plasma alpha-galactosidase A (α-gal-A) and globotriaosylsphingosine (lyso-Gb3), proteinuria, and kidney function tests of all FD patients before ERT were scanned from the hospital system. Periostin was studied from serum samples collected and stored before ERT. Parameters related to serum periostin levels in Fabry disease were investigated.

RESULTS

In FD patients, serum periostin was negatively correlated with age of first symptom and GFR; and positively correlated with proteinuria and lyso-Gb3. In regression analysis, we found that serum periostin was the only independent determinant of proteinuria in patients with Fabry disease. The serum periostin levels were significantly lower in patients with low proteinuria, and the serum periostin levels were correlated with proteinuria.

DISCUSSION

Periostin may be a valuable marker of Fabry nephropathy and proteinuria. Periostin seems to be one of the molecules that may have an important role in the management of the fibrotic process in Fabry nephropathy. We think that the role of periostin among these mechanisms is worth investigating. In addition to standard ERTs, periostin-reducing therapies may contribute to better kidney survival in Fabry disease. Progressive fibrosis processes caused by periostin in patients with Fabry disease are still a hidden issue waiting to be clarified. Progressive fibrosis processes caused by periostin in Fabry patients are still a hidden issue waiting to be clarified.

Impact of kidney biopsy on deciding when to initiate enzyme replacement therapy in children with Fabry disease

BACKGROUND

Recommendations on when to start enzyme replacement therapy (ERT) in children with Fabry disease (FD) differ between guidelines. In this study, kidney biopsies of a cohort of 14 untreated children and one treated child were analyzed for their morphologic changes to determine whether early initiation of ERT is indicated.

METHODS

All pediatric FD patients (< 18 years old) diagnosed between 2003 and 2021 in our department who received a kidney biopsy were enrolled. Clinical symptoms; laboratory parameters regarding kidney function, such as eGFR, plasma urea, protein-creatinine, and albumin/creatinine ratio; and 14 kidney biopsies prior to ERT and one under treatment were retrospectively analyzed.

RESULTS

A total of 14 patients were enrolled, including 9 male and 5 female children, aged 3-18 years (median age 11). Seven of the enrolled children were 10 years old or younger. Histological analysis of kidney biopsy samples revealed severe vacuolization and accumulation of inclusions in podocytes and renal tubules. The majority of cases had no FD-specific clinical or laboratory features independent of age, gender, or genotype. The youngest FD patient presenting with isolated abnormal kidney biopsy was 3 years old.

CONCLUSIONS

We demonstrate that histological lesions, typical for FD, can be observed in kidney biopsies at a very young age in patients without classical clinical symptoms or laboratory abnormalities. Thus, we recommend kidney biopsies as a possible tool for early diagnosis of renal involvement in FD. As a consequence of these early biopsy findings without a clinical correlate, an early initiation of ERT should be considered. A higher resolution version of the Graphical abstract is available as Supplementary information.

Treatment of Fabry Nephropathy: A Literature Review

Fabry disease is an X-linked inherited lysosomal storage disorder with a deficiency of α-galactosidase A activity, which results in the intracellular accumulation of globotriaosylceramide (Gb3) and related glycosphingolipids in various organs. Fabry nephropathy is one of the major complications of Fabry disease, and kidney damage is often related to cardiovascular disease and mortality. The treatment of Fabry nephropathy thus helps prolong life expectancy. Two treatment options for Fabry nephropathy and cardiopathy are now commercially available: enzyme replacement therapy (agalsidase α agalsidase β, and a biosimilar of agalsidase β) and pharmacological chaperone therapy (migalastat). In this review, we summarize the efficacy of these treatment options for Fabry nephropathy with respect to renal function, proteinuria, and renal pathological findings. We also describe the importance of adjunctive therapy for Fabry nephropathy.

Fabry Disease: Report of Two Cases with Uncommon Presentation

Fabry disease (FD) is a rare, lysosomal storage disorder characterized by multiorgan accumulation of predominantly globotriaosylceramide (GL3) and its metabolite. Resulting renal, cardiac, and cerebrovascular complications are crucial causes of morbidity and mortality in FD. Enzyme replacement therapy (ERT) shows promising outcomes for these patients, provided that therapy is initiated early. Thus, precise and early diagnosis of the disease is a pivotal factor determining the corollary of the disease. We report two cases of young adult males who presented to the nephrology department with proteinuria. A kidney biopsy was performed in both cases, which was suggestive of FD. The final conclusive diagnosis of FD was provided by electron microscopy.

Fabry Cardiomyopathy: Current Treatment and Future Options

Fabry disease is a multisystem X-linked lysosomal storage disorder caused by a mutation in the alpha-galactosidase A gene. Deficiency or reduced activity of alpha-galactosidase A (GLA) is leading to progressive intracellular accumulation of globotriaosylceramide (GL3) in various organs, including the heart, kidney and nerve system. Cardiac involvement is frequent and is evident as concentric left ventricular hypertrophy. Currently, the standard treatment is enzyme replacement therapy or chaperone therapy. However, early starting of therapy, before myocardial fibrosis has developed, is essential for long-term improvement of myocardial function. For future treatment options, various therapeutic approaches including gene therapy are under development. This review describes the current and potential future therapy options for Fabry cardiomyopathy.

Fabry Disease and the Heart: A Comprehensive Review

Fabry disease (FD) is an X-linked lysosomal storage disorder caused by mutations of the GLA gene that result in a deficiency of the enzymatic activity of α-galactosidase A and consequent accumulation of glycosphingolipids in body fluids and lysosomes of the cells throughout the body. GB3 accumulation occurs in virtually all cardiac cells (cardiomyocytes, conduction system cells, fibroblasts, and endothelial and smooth muscle vascular cells), ultimately leading to ventricular hypertrophy and fibrosis, heart failure, valve disease, angina, dysrhythmias, cardiac conduction abnormalities, and sudden death. Despite available therapies and supportive treatment, cardiac involvement carries a major prognostic impact, representing the main cause of death in FD. In the last years, knowledge has substantially evolved on the pathophysiological mechanisms leading to cardiac damage, the natural history of cardiac manifestations, the late-onset phenotypes with predominant cardiac involvement, the early markers of cardiac damage, the role of multimodality cardiac imaging on the diagnosis, management and follow-up of Fabry patients, and the cardiac efficacy of available therapies. Herein, we provide a comprehensive and integrated review on the cardiac involvement of FD, at the pathophysiological, anatomopathological, laboratory, imaging, and clinical levels, as well as on the diagnosis and management of cardiac manifestations, their supportive treatment, and the cardiac efficacy of specific therapies, such as enzyme replacement therapy and migalastat.

The role of Immunity in Fabry Disease and Hypertension: A Review of a Novel Common Pathway

Fabry disease is a progressive, X-linked inherited lysosomal storage disorder where accumulation of glycosphingolipids increases the risk for early cardiovascular complications, including heart failure, stroke, and end stage renal disease. Besides disease-specific therapy, blood pressure (BP) control is of central importance in Fabry disease to reduce disease progression and improve prognosis. Both Fabry disease and hypertension are characterized by the activation of the innate component of the immune system, with Toll-like receptor 4 (TLR4) as a common trigger to the inflammatory cascade. The renin-angiotensin system (RAS) participates in the establishment of low-grade chronic inflammation and redox unbalance that contribute to organ damage in the long term. Besides exploiting the anti-inflammatory effects of RAS blockade and enzyme replacement therapy, targeted therapies acting on the immune system represent an appealing field of research in these conditions. The aim of this narrative review is to examine the issue of hypertension in the setting of Fabry disease, focusing on the possible determinants of their reciprocal relationship, as well as on the related clinical and therapeutic implications.

Therapeutic advances in Fabry disease: The future awaits

Fabry disease (FD) is an X-linked disorder caused by mutations in GLA gene responsible for coding of the lysosomal enzyme alpha-galactosidase A(α-GAL). The resultant accumulation of globotriaosylceramide (Gb-3) leads to multisystemic disease including progressive chronic kidney disease, hypertrophic cardiomyopathy, stroke, angiokeratomas and corneal whorls. Current treatments include enzyme replacement therapy (ERT), along with recent advent of chaperone therapy. ERT has not shown to have dramatic improvement in outcomes for all organ systems, with benefit mostly seen in kidney disease and reduction in left ventricular hypertrophy. ERT, however, is associated with formation of anti-drug antibodies and requirement of long-term venous access, while chaperone therapy can only be used in amenable mutations. A multitude of therapies are now under investigation in various phases of clinical trials. These include pegylated form of α-GAL (pegunigalsidase alpha), gene therapy (both in-vivo and ex-vivo methods), mRNA therapy (inducing production of α-GAL) and substrate reduction therapy (inhibitors of glucosylceramide synthase leading to reduction of Gb-3). This review encapsulates literature pertaining to current and investigational therapies for FD.

Developments in the treatment of Fabry disease

Enzyme replacement therapy (ERT) with recombinant α-galactosidase A (r-αGAL A) for the treatment of Fabry disease has been available for over 15 years. Long-term treatment may slow down disease progression, but cardiac, renal, and cerebral complications still develop in most patients. In addition, lifelong intravenous treatment is burdensome. Therefore, several new treatment approaches have been explored over the past decade. Chaperone therapy (Migalastat; 1-deoxygalactonojirimycin) is the only other currently approved therapy for Fabry disease. This oral small molecule aims to improve enzyme activity of mutated α-galactosidase A and can only be used in patients with specific mutations. Treatments currently under evaluation in (pre)clinical trials are second generation enzyme replacement therapies (Pegunigalsidase-alfa, Moss-aGal), substrate reduction therapies (Venglustat and Lucerastat), mRNA- and gene-based therapy. This review summarises the knowledge on currently available and potential future options for the treatment of Fabry disease.

Agalsidase beta treatment slows estimated glomerular filtration rate loss in classic Fabry disease patients: results from an individual patient data meta-analysis

Background

Fabry disease is a rare, X-linked genetic disorder that, if untreated in patients with the Classic phenotype, often progresses to end-stage kidney disease. This meta-analysis determined the effect of agalsidase beta on loss of estimated glomerular filtration rate (eGFR) in the Classic phenotype using an expansive evidence base of individual patient-level data.

Methods

The evidence base included four Sanofi-Genzyme studies and six studies from a systematic literature review. These were restricted to Classic Fabry patients meeting the eligibility criteria from Phases III and IV agalsidase beta trials, including 315 patients (161 treated). Linear regression was first used to model annual change in eGFR for each patient and the resulting annualized eGFR slopes were modelled with treatment and covariates using quantile regression. These results were then used to estimate median annualized eGFR change in agalsidase beta treated versus untreated groups.

Results

Imbalances across treatment groups were found in baseline age, sex and proteinuria, but not in the use of renin–angiotensin system blockers. The adjusted model suggests that treated (agalsidase beta) patients experienced a slower median eGFR decrease [2.46 mL/min/1.73 m²/year slower; 95% confidence interval (CI) 0.63–4.29; P = 0.0087] than comparable untreated patients. The median eGFR decrease was 2.64 mL/min/1.73 m²/year slower (95% CI 0.53–4.78; P = 0.0141) in treated Classic males.

Conclusions

Using an expansive evidence base and robust modelling approach, these data indicate that agalsidase beta-treated patients with the Classic phenotype conserve their renal function better than untreated patients.

Why systematic literature reviews in Fabry disease should include all published evidence

Fabry disease is an X-linked inherited, progressive disorder of lipid metabolism resulting from the deficient activity of the enzyme α-galactosidase. Enzyme replacement therapy (ERT) with recombinant agalsidase, with intravenous infusions of either agalsidase beta or agalsidase alfa, is available and clinical experience now exceeds 15 years. There are very few randomised, placebo-controlled clinical trials evaluating the outcomes of ERT. Data are often derived from observational, registry-based studies and case reports. Pooled analysis of data from different sources may be limited by the heterogeneity of the patient populations, outcomes and treatment. Therefore, comprehensive systematic literature reviews of unpooled data are needed to determine the effects of ERT on disease outcomes. A systematic literature search was conducted in the Embase and PubMed (MEDLINE) databases to retrieve original articles that evaluated outcomes of ERT in patients with Fabry disease; the outcome data were analysed unpooled. The literature analysis included the full range of published literature including observational studies and case series/case reports. Considerable heterogeneity was found among the studies, with differences in sample size, statistical methods, ERT regimens and patient demographic and clinical characteristics. We have demonstrated the value of performing an unpooled systematic literature review of all published evidence of ERT outcomes in Fabry disease, highlighting that in a rare genetic disorder like Fabry disease, which is phenotypically diverse, different patient populations can require different disease management and therapeutic goals depending on age, genotype, and disease severity/level of organ involvement. In addition, these findings are valuable to guide the design and reporting of new clinical studies.

Safety and effectiveness of enzyme replacement therapy with agalsidase alfa in patients with Fabry disease: Post-marketing surveillance in Japan

Fabry disease is a rare X-linked inherited multisystem disorder resulting from deficiency of the lysosomal enzyme alpha-galactosidase A. Currently, specific therapies, including enzyme replacement therapies, are available for Fabry disease, but clinical trials provide limited information on long-term safety and effectiveness. Agalsidase alfa was approved in Japan in 2006. The post-marketing surveillance study of all patients receiving agalsidase alfa to evaluate its long-term safety and effectiveness as a mandatory condition for its approval had been conducted for 8 years (from February 2007 to March 2015). A total of 493 patients were included in this analysis of safety and effectiveness. The overall mean follow-up period was 3.5 years (range, 0.0-7.9 years). The percentage of patients with adverse drug reactions was 24.5% (121/493) and 12.6% had infusion-related reactions (62/493). In the 256 patients without prior enzyme replacement therapy whose IgG antibody data were available, 17 were IgG antibody positive (6.6%). However, the chronological correlation between seroconversion and the incidence of infusion-related reactions was not clear. The mean brief pain inventory score of the worst pain decreased in patients with moderate and severe pain at baseline. Plasma Gb₃ and urine sediment Gb₃ in males with classical Fabry disease without prior enzyme replacement therapy significantly decreased. The mean yearly changes in eGFR (mL/min/1.73 m²) ranged from -2.88 to +1.00 in males with classical Fabry disease, from -2.04 to -0.95 in males with non-typical variant and from -2.64 to -1.02 in females. The lower eGFR or the more proteinuria at baseline, the faster the decrease in eGFR of the patients was observed. There was no substantial difference in cardiac parameters (left ventricular mass index, E/A wave ratio, ejection fraction, and QRS duration). In conclusion, agalsidase alfa, 0.2 mg/kg every other week, was well tolerated and controlled the progression of symptoms (especially renal and cardiac) of Fabry disease in adults. Enzyme replacement therapy should be started in Japanese patients before cardiac and/or renal symptoms of Fabry disease develop.

The effect of enzyme replacement therapy on clinical outcomes in male patients with Fabry disease: A systematic literature review by a European panel of experts

Background

Enzyme replacement therapy (ERT) with recombinant human α-galactosidase has been available for the treatment of Fabry disease since 2001 in Europe and 2003 in the USA. Treatment outcomes with ERT are dependent on baseline patient characteristics, and published data are derived from heterogeneous study populations.

Methods

We conducted a comprehensive systematic literature review of all original articles on ERT in the treatment of Fabry disease published up until January 2017. This article presents the findings in adult male patients.

Results

Clinical evidence for the efficacy of ERT in adult male patients was available from 166 publications including 36 clinical trial publications. ERT significantly decreases globotriaosylceramide levels in plasma, urine, and in different kidney, heart, and skin cell types, slows the decline in estimated glomerular filtration rate, and reduces/stabilizes left ventricular mass and cardiac wall thickness. ERT also improves nervous system, gastrointestinal, pain, and quality of life outcomes.

Conclusions

ERT is a disease-specific treatment for patients with Fabry disease that may provide clinical benefits on several outcomes and organ systems. Better outcomes may be observed when treatment is started at an early age prior to the development of organ damage such as chronic kidney disease or cardiac fibrosis. Consolidated evidence suggests a dose effect. Data described in male patients, together with female and paediatric data, informs clinical practice and therapeutic goals for individualized treatment.

European expert consensus statement on therapeutic goals in Fabry disease

BACKGROUND

Fabry disease, an inherited lysosomal storage disorder, causes multi-organ pathology resulting in substantial morbidity and a reduced life expectancy. Although Fabry disease is an X-linked disorder, both genders may be affected, but generally to a lesser extent in females. The disease spectrum ranges from classic early-onset disease to non-classic later-onset phenotypes, with complications occurring in multiple organs or being confined to a single organ system depending on the stage of the disease. The impact of therapy depends upon patient- and disease-specific factors and timing of initiation.

METHODS

A European panel of experts collaborated to develop a set of organ-specific therapeutic goals for Fabry disease, based on evidence identified in a recent systematic literature review and consensus opinion.

RESULTS

A series of organ-specific treatment goals were developed. For each organ system, optimal treatment strategies accounted for inter-patient differences in disease severity, natural history, and treatment responses as well as the negative burden of therapy and the importance of multidisciplinary care. The consensus therapeutic goals and proposed patient management algorithm take into account the need for early disease-specific therapy to delay or slow the progression of disease as well as non-specific adjunctive therapies that prevent or treat the effects of organ damage on quality of life and long-term prognosis.

CONCLUSIONS

These consensus recommendations help advance Fabry disease management by considering the balance between anticipated clinical benefits and potential therapy-related challenges in order to facilitate individualized treatment, optimize patient care and improve quality of life.

Fabry Nephropathy: An Evidence-Based Narrative Review

Fabry disease (FD) is a rare, X-linked disorder caused by mutations in the GLA gene encoding the enzyme α-galactosidase A. Complete or partial deficiency in this enzyme leads to intracellular accumulation of globotriaosylceramide (Gb3) and other glycosphingolipids in many cell types throughout the body, including the kidney. Progressive accumulation of Gb3 in podocytes, endothelial cells, epithelial cells, and tubular cells contribute to the renal symptoms of FD, which manifest as proteinuria and reduced glomerular filtration rate leading to renal insufficiency. A correct diagnosis of FD, although challenging, has considerable implications regarding treatment, management, and counseling. The diagnosis may be confirmed by demonstrating the enzyme deficiency in males and by identifying the specific GLA gene mutation in male and female patients. Treatment with enzyme replacement therapy, as part of the therapeutic strategy to prevent complications of the disease, may be beneficial in stabilizing renal function or slowing its decline, particularly in the early stages of the disease. Emergent treatments for FD include the recently approved chaperone molecule migalastat for patients with amenable mutations. The objective of this report is to provide an updated overview on Fabry nephropathy, with a focus on the most relevant aspects of its epidemiology, diagnosis, pathophysiology, and treatment options.

Biomarkers and Imaging Findings of Anderson-Fabry Disease-What We Know Now

Anderson–Fabry disease (AFD) is an X-linked lysosomal storage disorder, caused by deficiency or absence of the alpha-galactosidase A activity, with a consequent glycosphingolipid accumulation. Biomarkers and imaging findings may be useful for diagnosis, identification of an organ involvement, therapy monitoring and prognosis. The aim of this article is to review the current available literature on biomarkers and imaging findings of AFD patients. An extensive bibliographic review from PubMed, Medline and Clinical Key databases was performed by a group of experts from nephrology, neurology, genetics, cardiology and internal medicine, aiming for consensus. Lyso-GB3 is a valuable biomarker to establish the diagnosis. Proteinuria and creatinine are the most valuable to detect renal damage. Troponin I and high-sensitivity assays for cardiac troponin T can identify patients with cardiac lesions, but new techniques of cardiac imaging are essential to detect incipient damage. Specific cerebrovascular imaging findings are present in AFD patients. Techniques as metabolomics and proteomics have been developed in order to find an AFD fingerprint. Lyso-GB3 is important for evaluating the pathogenic mutations and monitoring the response to treatment. Many biomarkers can detect renal, cardiac and cerebrovascular involvement, but none of these have proved to be important to monitoring the response to treatment. Imaging features are preferred in order to find cardiac and cerebrovascular compromise in AFD patients.

Skin Globotriaosylceramide 3 Load Is Increased in Men with Advanced Fabry Disease

BACKGROUND

The X-chromosomally linked life-limiting Fabry disease (FD) is associated with deposits of the sphingolipid globotriaosylceramide 3 (Gb3) in various tissues. Skin is easily accessible and may be used as an additional diagnostic and follow-up medium. Our aims were to visualize skin Gb3 deposits in FD patients applying immunofluorescence and to determine if cutaneous Gb3 load correlates with disease severity.

METHODS

At our Fabry Center for Interdisciplinary Therapy we enrolled 84 patients with FD and 27 healthy controls. All subjects underwent 5-mm skin punch biopsy at the lateral lower leg and the back. Skin samples were processed for immunohistochemistry using antibodies against CD77 (i.e. Gb3). Cutaneous Gb3 deposition was quantified in a blinded manner and correlated to clinical data.

RESULTS

We found that Gb3 load was higher in distal skin of male FD patients compared to healthy controls (p<0.05). Men (p<0.01) and women (p<0.05) with a classic FD phenotype had higher distal skin Gb3 load than healthy controls. Men with advanced disease as reflected by impaired renal function, and men and women with small fiber neuropathy had more Gb3 deposits in distal skin samples than males with normal renal function (p<0.05) and without small fiber neuropathy. Gb3 deposits were not different between patients with and without enzyme replacement therapy.

CONCLUSIONS

Immunofluorescence on minimally invasive skin punch biopsies may be useful as a tool for assessment and follow-up in FD patients.

Fabry Disease: A Disorder of Childhood Onset

BACKGROUND

Fabry disease, an X-linked disorder of glycosphingolipids, markedly increases the risk of systemic vasculopathy, ischemic stroke, small-fiber peripheral neuropathy, cardiac dysfunction, and chronic kidney disease.

METHODS

We performed an extensive PubMed search on the topic of Fabry disease and drew from our cumulative 43 years of experience.

RESULTS

Most of these complications are nonspecific in nature and clinically indistinguishable from similar abnormalities that occur in the context of more common disorders in the general population. This disease is caused by variants of the GLA gene, and its incidence may have been underestimated. However, one must also guard against overdiagnosis of Fabry disease and unjustified enzyme replacement therapy, because some of the gene variants are benign. Specific therapy for Fabry disease has been developed in the last few years, but its clinical effect has been modest. Novel therapeutic agents are being developed. Standard "nonspecific" medical and surgical therapy is necessary and effective in slowing deterioration or compensating for organ failure in patients with Fabry disease.

CONCLUSIONS

Fabry disease is a treatable and modifiable genetic risk factor for a myriad of clinical organ complications. Fabry disease may be frequently overlooked but on occasion overdiagnosed.

Fabry's Disease: Case Series and Review of Literature

Fabry's disease is an X-linked lysosomal storage disorder caused by a deficiency of alpha-galactosidase A enzyme with the progressive accumulation of globotriaosylceramide in vascular endothelial cells leading to cardiovascular, renal, gastrointestinal, neuropathic, lenticular, and dermatological manifestations. It is a rare cause of end-stage renal disease. It classically affects males whereas 10-15% of female heterozygote carriers are affected depending on localization. Both the FD and its association with ESRD is rare. With this background, this case series of five patient's along with the review of literature is presented here.

Left Ventricular Geometry and Blood Pressure as Predictors of Adverse Progression of Fabry Cardiomyopathy

Background

In spite of several research studies help to describe the heart in Fabry disease (FD), the cardiomyopathy is not entirely understood. In addition, the impact of blood pressure and alterations in geometry have not been systematically evaluated.

Methods

In 74 FD patients (mean age 36±12 years; 45 females) the extent of myocardial fibrosis and its progression were quantified using cardiac magnetic-resonance-imaging with late enhancement technique (LE). Results were compared to standard echocardiography complemented by 2D-speckle-tracking, 3D-sphericity-index (SI) and standardized blood pressure measurement. At baseline, no patient received enzyme replacement therapy (ERT). After 51±24 months, a follow-up examination was performed.

Results

Systolic blood pressure (SBP) was higher in patients with vs. without LE: 123±17 mmHg vs. 115±13 mmHg; P = 0.04. A positive correlation was found between SI and the amount of LE-positive myocardium (r = 0.51; P<0.001) indicating an association of higher SI in more advanced stages of the cardiomyopathy. SI at baseline was positively associated with the increase of LE-positive myocardium during follow-up. The highest SBP (125±19 mmHg) and also the highest SI (0.32±0.05) was found in the subgroup with a rapidly increasing LE (ie, ≥0.2% per year; n = 16; P = 0.04). Multivariate logistic regression analysis including SI, SBP, EF, left ventricular volumes, wall thickness and NT-proBNP adjusted for age and sex showed SI as the most powerful parameter to detect rapid progression of LE (AUC = 0.785; P<0.05).

Conclusions

LV geometry as assessed by the sphericity index is altered in relation to the stage of the Fabry cardiomyopathy. Although patients with FD are not hypertensive, the SBP has a clear impact on the progression of the cardiomyopathy.

Antiproteinuric therapy and Fabry nephropathy: factors associated with preserved kidney function during agalsidase-beta therapy

Background

Nephropathy is an important feature of classical Fabry disease, which results in alpha-galactosidase A deficiency and cellular globotriaosylceramide accumulation. We report the safety and efficacy of antiproteinuric therapy with ACE inhibitors or angiotensin II receptor blockers (ARBs) in a study of classical Fabry patients receiving recombinant agalsidase-beta therapy.

Methods and design

The goal was maintenance of urine protein to creatinine ratio (UPCR) <0.5 g/g or a 50% reduction in baseline UPCR for 24 patients at eight study sites. The change in estimated glomerular filtration rate (eGFR) was assessed over 21 months of treatment.

Results

18 out of 24 patients achieved the UPCR goal with eGFR slopes that were significantly better than six patients who did not achieve the UPCR goal (−3.6 (−4.8 to −1.1) versus −7.0 (−9.0 to −5.6) mL/min/1.73 m²/year, respectively, p=0.018). Despite achieving the UPCR goal, 67% (12/18 patients) still progressed with an eGFR slope <−2 mL/min/1.73 m²/year. Regression analysis showed that increased age at initiation of agalsidase-beta therapy was significantly associated with worsened kidney outcome. Hypotension and hyperkalaemia occurred in seven and eight patients, respectively, which required modification of antiproteinuric therapy but was not associated with serious adverse events.

Conclusions

This study documents the effectiveness of agalsidase-beta (1 mg/kg/2 weeks) and antiproteinuric therapy with ACE inhibitors and/or ARB in patients with severe Fabry nephropathy. Patients had preservation of kidney function if agalsidase-beta treatment was initiated at a younger age, and UPCR maintained at or below 0.5 g/g with antiproteinuric therapy.

Trial registration number

NCT00446862.

Lyso-Gb3 activates Notch1 in human podocytes

Podocyte injury is an early feature of Fabry nephropathy, but the molecular mechanisms of podocyte injury are poorly understood. Lyso-Gb3 accumulates in serum in Fabry disease and increases extracellular matrix synthesis in podocytes. We explored the contribution of Notch1 signaling, a mediator of podocyte injury, to lyso-Gb3-elicited responses in cultured human podocytes. At clinically relevant concentrations, lyso-Gb3 activates podocyte Notch1 signaling, resulting in increased active Notch1 and HES1, a canonical Notch transcriptional target. A γ-secretase inhibitor or specific Notch1 small interfering RNA (siRNA) inhibited HES1 upregulation in response to lyso-Gb3. Notch1 siRNA or γ-secretase inhibition also prevented the lyso-Gb3-induced upregulation of Notch1, Notch ligand Jagged1 and chemokine (MCP1, RANTES) expression. Notch siRNA prevented the activation of nuclear factor kappa B (NFκB), and NFκB activation contributed to Notch1-mediated inflammatory responses as the NFκB inhibitor, parthenolide, prevented lyso-Gb3-induced chemokine upregulation. Notch1 also mediates fibrogenic responses in podocytes as Notch siRNA prevented lyso-Gb3 upregulation of fibronectin mRNA. Supporting the clinical relevance of cell culture findings, active Notch1, Jagged1 and HES1 were observed in Fabry kidney biopsies. Lyso-Gb3 elicited similar responses in mouse kidney. In conclusion, lyso-Gb3 promotes Notch1-mediated inflammatory and fibrogenic responses in podocytes that may contribute to Fabry nephropathy.

Fabry disease and the heart

Fabry disease is induced by a mutation in the alpha-galactosidase A gene, causing a deficiency of the enzyme alpha-galactosidase A. (1) The enzyme defect leads to progressive intracellular accumulation of globotriaosylceramide in lysosomes of various tissues and organs, including heart, kidney and nerve system. Cardiac involvement is common and is presenting as concentric left ventricular hypertrophy. Myocardial replacement fibrosis is a typical feature of more advanced stages of Fabry cardiomyopathy, first limited to the mid-myocardial layers of the basal postero-lateral wall, then spreading to transmural fibrosis. Since 2001, enzyme replacement therapy is available. If therapy is started early, before myocardial fibrosis has developed, a long-term improvement of myocardial morphology, function and exercise capacity can be achieved. In end-stage cardiomyopathy enzyme replacement therapy might prevent further progression of the disease. This review provides an overview of Fabry disease, with a focus on cardiac involvement with its characteristic features, clinical presentation and possible treatment.

The kidney in Fabry's disease

Fabry disease (FD) is an X-linked disease in which mutations of the GLA gene result in a deficiency of the enzyme α-galactosidase A and subsequent progressive, intralysosomal deposition of undegraded glycosphingolipid products, primarily globotriaosylceramide, in multiple organs. Progressive nephropathy is one of the main features of FD and is marked by an insidious development, with an overall rate of progression of chronic kidney disease (CKD) very similar to diabetic nephropathy. Untreated patients usually develop end stage renal disease in their 50s. The decline in renal function in FD is adversely affected by male gender, advanced CKD, hypertension and, in particular, severe proteinuria. Enzyme replacement therapy (ERT) has been shown to slow the progression of Fabry nephropathy. The current consensus is that ERT should be started in all men and women with signs of renal involvement.

Fabry nephropathy: a review - how can we optimize the management of Fabry nephropathy?

Fabry disease is a rare, X-linked, lysosomal storage disease caused by mutations in the gene encoding the enzyme alpha-galactosidase A. Complete or partial deficiency in this enzyme leads to intracellular accumulation of globotriaosylceramide (Gb₃) and related glycosphingolipids in many cell types throughout the body, including the kidney. Progressive accumulation of Gb₃ in podocytes, epithelial cells and the tubular cells of the distal tubule and loop of Henle contribute to the renal symptoms of Fabry disease, which manifest as proteinuria and reduced glomerular filtration rate leading to chronic kidney disease and progression to end-stage renal disease. Early diagnosis and timely initiation of treatment of Fabry renal disease is an important facet of disease management. Initiating treatment with enzyme replacement therapy (ERT; agalsidase alfa, Replagal^®, Shire; agalsidase beta, Fabrazyme^®, Genzyme) as part of a comprehensive strategy to prevent complications of the disease, may be beneficial in stabilizing renal function or slowing its decline. Early initiation of ERT may also be more effective than initiating therapy in patients with more advanced disease. Several strategies are required to complement the use of ERT and treat the myriad of associated symptoms and organ involvements. In particular, patients with renal Fabry disease are at risk of cardiovascular events, such as high blood pressure, cardiac arrhythmias and stroke. This review discusses the management of renal involvement in Fabry disease, including diagnosis, treatments, and follow-up, and explores recent advances in the use of biomarkers to assist with diagnosis, monitoring disease progression and response to treatment.

Natural course of Fabry disease and the effectiveness of enzyme replacement therapy: a systematic review and meta-analysis: effectiveness of ERT in different disease stages

OBJECTIVE

Current available evidence on long-term effectiveness of enzyme replacement therapy (ERT) for Fabry disease is limited. More insight is needed whether ERT effectiveness differs in patients with and without baseline end-organ damage.

DESIGN

Through a systematic review, untreated and ERT treated males and females with Fabry disease were compared for main clinical outcomes: renal function, left ventricular mass (LVmass), cerebral white matter lesions (WMLs) and end-organ complications. Through a meta-analysis ERT effectiveness was estimated in different disease stages.

DATA EXTRACTION

Two reviewers assessed quality of the included studies according to guidelines for prognosis research. Data were synthesized using a random effects meta-analysis.

RESULTS

Thirty-one studies were systematically reviewed while six studies were included in the meta-analysis. In patients with a GFR > 60 ml/min/1.73 m(2), decline of renal function was similar for treated and untreated patients. Only ERT treated males with a GFR < 60 ml/min/1.73 m(2) had a slower rate of decline in renal function, possibly attributable to anti-proteinuric therapy. Regardless of left ventricular hypertrophy (LVH) at baseline, LVmass remained stable or increased in males despite ERT, however at a slower rate compared to untreated male patients. In ERT treated females with LVH LVmass decreased, and remained stable in females without LVH. WMLs can not be prevented by ERT. Stroke, cardiac and end-stage renal complications develop, though the incidence of new complications seems to be reduced during ERT.

CONCLUSION

ERT is effective in reducing LVH, but has a limited effect on renal function. Improved treatment options are needed for Fabry disease.

Outcomes of patients treated through the Canadian Fabry disease initiative

BACKGROUND

The Canadian Fabry disease initiative (CFDI) tracks outcomes of subjects with Fabry disease treated enzyme replacement therapy (ERT) given to subjects who meet evidence-based treatment guidelines and cardiovascular risk factor modification.

METHODS

We report 5 year follow-up data on 362 subjects for a composite endpoint (death, neurologic or cardiovascular events, development of end-stage renal disease or sustained increase in serum creatinine of 50% from baseline).

RESULTS

At enrollment, 86 subjects had previously received ERT (Cohort 1a) and 67 subjects were newly started (Cohort 1b) and randomized to agalsidase alfa or agalsidase beta. 209 subjects did not initially meet ERT criteria (Cohort 1c), 25 of whom met ERT criteria in follow-up and were moved to Cohort 1b (total N=178 ERT treated subjects). Use of supportive therapies such as aspirin (78%), renin-angiotensin blockade (59%), and statins (55%) was common in ERT treated subjects. In Cohort 1a, 32 subjects met the composite endpoint with 8 deaths. In Cohort 1b, 16 subjects met the composite endpoint with 1 death. Cohort 1b had fewer clinical events than Cohort 1a (p=0.039) suggesting that the treatment protocol was effective in targeting subjects at an earlier stage. 19.4% of Cohort 1b subjects on agalsidase alfa and 13.3% on agalsidase beta had a clinical event (p=0.57). 10 Cohort 1c subjects had clinical events, none of which would have been prevented by earlier use of ERT.

CONCLUSIONS

Cardiovascular risk factor modification and targeted use of ERT reduce the risk of adverse outcomes related to Fabry disease.

Increased arterial diameters in the posterior cerebral circulation in men with Fabry disease

A high load of white matter lesions and enlarged basilar arteries have been shown in selected patients with Fabry disease, a disorder associated with an increased stroke risk. We studied a large cohort of patients with Fabry disease to differentially investigate white matter lesion load and cerebral artery diameters. We retrospectively analyzed cranial magnetic resonance imaging scans of 87 consecutive Fabry patients, 20 patients with ischemic stroke, and 36 controls. We determined the white matter lesion load applying the Fazekas score on fluid-attenuated inversion recovery sequences and measured the diameters of cerebral arteries on 3D-reconstructions of the time-of-flight-MR-angiography scans. Data of different Fabry patient subgroups (males-females; normal-impaired renal function) were compared with data of patients with stroke and controls. A history of stroke or transient ischemic attacks was present in 4/30 males (13%) and 5/57 (9%) females with Fabry disease, all in the anterior circulation. Only one man with Fabry disease showed confluent cerebral white matter lesions in the Fazekas score assessment (1%). Male Fabry patients had a larger basilar artery (p<0.01) and posterior cerebral artery diameter (p<0.05) compared to male controls. This was independent of disease severity as measured by renal function and did not lead to changes in arterial blood flow properties. A basilar artery diameter of >3.2 mm distinguished between men with Fabry disease and controls (sensitivity: 87%, specificity: 86%, p<0.001), but not from stroke patients. Enlarged arterial diameters of the posterior circulation are present only in men with Fabry disease independent of disease severity.

Fibrosis: a key feature of Fabry disease with potential therapeutic implications

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.

Impaired small fiber conduction in patients with Fabry disease: a neurophysiological case-control study

BACKGROUND

Fabry disease is an inborn lysosomal storage disorder which is associated with small fiber neuropathy. We set out to investigate small fiber conduction in Fabry patients using pain-related evoked potentials (PREP).

METHODS

In this case-control study we prospectively studied 76 consecutive Fabry patients for electrical small fiber conduction in correlation with small fiber function and morphology. Data were compared with healthy controls using non-parametric statistical tests. All patients underwent neurological examination and were investigated with pain and depression questionnaires. Small fiber function (quantitative sensory testing, QST), morphology (skin punch biopsy), and electrical conduction (PREP) were assessed and correlated. Patients were stratified for gender and disease severity as reflected by renal function.

RESULTS

All Fabry patients (31 men, 45 women) had small fiber neuropathy. Men with Fabry disease showed impaired cold (p < 0.01) and warm perception (p < 0.05), while women did not differ from controls. Intraepidermal nerve fiber density (IENFD) was reduced at the lower leg (p < 0.001) and the back (p < 0.05) mainly of men with impaired renal function. When investigating A-delta fiber conduction with PREP, men but not women with Fabry disease had lower amplitudes upon stimulation at face (p < 0.01), hands (p < 0.05), and feet (p < 0.01) compared to controls. PREP amplitudes further decreased with advance in disease severity. PREP amplitudes and warm (p < 0.05) and cold detection thresholds (p < 0.01) at the feet correlated positively in male patients.

CONCLUSION

Small fiber conduction is impaired in men with Fabry disease and worsens with advanced disease severity. PREP are well-suited to measure A-delta fiber conduction.

Initially Nondiagnosed Fabry's Disease when Electron Microscopy Is Lacking: The Continuing Story of Focal and Segmental Glomerulosclerosis

Focal and segmental glomerulosclerosis is classified as either primary or secondary. We present a patient with a past history of biopsy-proven focal and segmental glomerulosclerosis. Despite initial response to dual blockade and steroids, proteinuria raised when steroids were decreased. After the patient was restarted on steroids, proteinuria did not improve. Another biopsy confirmed the previous diagnosis but suggested Fabry's disease, later confirmed by electron microscopy, α-galactosidase A serum and leukocyte deficiency as well as genetic studies. Proteinuria decreased when agalsidase β was prescribed in parallel with steroid tapering, increased with steroid discontinuation and improved with meprednisone administration. This report highlights the relevance of electron microscopy in kidney biopsy. In glomerulosclerosis, despite specific treatment, secondary hemodynamic and immunologic pathways may contribute to the development of proteinuria and accelerate the renal disease progression due to the primary disease. We discuss possible pathophysiologic pathways involved in proteinuria in Fabry's disease according to the biopsy and the therapeutic response.

Renal complications of Fabry disease in children

Fabry disease is an X-linked α-galactosidase A deficiency, resulting in accumulation of glycosphingolipids, especially globotriaosylceramide, in cells in different organs in the body. Renal failure is a serious complication of this disease. Fabry nephropathy lesions are present and progress in childhood while the disease commonly remains silent by routine clinical measures. Early and timely diagnosis of Fabry nephropathy is crucial since late initiation of enzyme replacement therapy may not halt progressive renal dysfunction. This may be challenging due to difficulties in diagnosis of Fabry disease in children and absence of a sensitive non-invasive biomarker of early Fabry nephropathy. Accurate measurement of glomerular filtration rate and regular assessment for proteinuria and microalbuminuria are useful, though not sensitive enough to detect early lesions in the kidney. Recent studies support the value of renal biopsy in providing histological information relevant to kidney function and prognosis, and renal biopsy could potentially be used to guide treatment decisions in young Fabry patients. This review aims to provide an update of the current understanding, challenges, and needs to better approach renal complications of Fabry disease in children.

Fabry nephropathy: indications for screening and guidance for diagnosis and treatment by the European Renal Best Practice

Fabry disease (FD) is an X-linked disorder of glycosphingolipid catabolism resulting in the accumulation of glycolipids including globotriaosylceramide in cells of various tissues resulting in end-organ manifestations. Initially, FD is typically characterized by angiokeratoma and recurrent episodes of neuropathic pain in the extremities occurring during childhood or adolescence. Most affected patients also exhibit a decreased ability to sweat. Later in life, FD results in left ventricular hypertrophy, proteinuria, renal failure and stroke. These later disease manifestations are non-specific and also common in diabetes, hypertension and atheromatosis and thus for most practitioners do not point into the direction of FD. As a consequence, FD is under-diagnosed and screening of high-risk groups is important for case finding, as is a thorough pedigree analysis of affected patients. In the nephrology clinic, we suggest to screen patients for FD when there is unexplained chronic kidney disease in males younger than 50 years and females of any age. In men, this can be performed by measuring α-galactosidase A activity in plasma, white blood cells or dried blood spots. In women, mutation analysis is necessary, as enzyme measurement alone could miss over one-third of female Fabry patients. A multidisciplinary team should closely monitor all known Fabry patients, with the nephrologist screening kidney impairment (glomerular filtration rate and proteinuria) on a regular basis. Transplanted Fabry patients have a higher mortality than the regular transplant population, but have acceptable outcomes, compared with Fabry patients remaining on dialysis. It is unclear whether enzyme replacement therapy (ERT) prevents deterioration of kidney function. In view of the lack of compelling evidence for ERT, and the low likelihood that a sufficiently powered randomized controlled trial on this topic will be performed, data of all patients with FD should be collected in a central registry.

Enzyme replacement therapy in patients with Fabry disease: state of the art and review of the literature

Anderson-Fabry disease is an X-linked lysosomal storage disorder resulting from the deficiency of the hydrolytic enzyme alpha galactosidase A, with consequent accumulation of globotrioasoyl ceramide in cells and tissues of the body, resulting in a multi-system pathology including end organ failure. In the classical phenotype, cardiac failure, renal failure and stroke result in a reduced median life expectancy. The current causal treatment for Fabry disease is the enzyme replacement therapy (ERT): two different products, Replagal (agalsidase alfa) and Fabrazyme (agalsidase beta), have been commercially available in Europe for almost 10 years and they are both indicated for long-term treatment. In fact, clinical trials, observational studies and registry data have provided many evidences for safety and efficacy of ERT in improving symptoms of pain, gastrointestinal disturbances, hypohidrosis, left ventricular mass index, glomerular filtration rate and quality of life. Few data are available on comparison of the two treatments and on the clinical course of the disease. This article reviews the published evidence for clinical efficacy of the two available enzyme preparations.

Cardiomyopathy and response to enzyme replacement therapy in a male mouse model for Fabry disease

Fabry disease is an X-linked disorder of glycosphingolipid metabolism that results in progressive accumulation of neutral glycosphingolipids, (predominately globotriaosylceramide; GL-3) in lysosomes, as well as other cellular compartments and the extracellular space. Our aim was to characterize the cardiac phenotype of male knock-out mice that are deficient in alpha-galactosidase A activity, as a model for Fabry disease and test the efficacy of Enzyme Replacement Therapy with agalsidase-beta. Male mice (3–4 months of age) were characterized with awake blood pressure and heart rate measurements, cardiac echocardiography and electrocardiography measurements under light anesthesia, histological studies and molecular studies with real-time polymerase chain reaction. The Fabry knock-out mouse has bradycardia and lower blood pressure than control wild type (CB7BL/6J) mice. In Fabry knock-out mice, the cardiomyopathy associated mild hypertrophy at echography with normal systolic LV function and mild diastolic dysfunction. Premature atrial contractions were more frequent in without conduction defect. Heart weight normalized to tibial length was increased in Fabry knock-out mice. Ascending aorta dilatation was observed. Molecular studies were consistent with early stages of cardiac remodeling. A single dose of agalsidase-beta (3 mg/kg) did not affect the LV hypertrophy, function or heart rate, but did improve the mRNA signals of early cardiac remodeling. In conclusion, the alpha-galactosidase A deficient mice at 3 to 4 months of age have cardiac and vascular alterations similar to that described in early clinical stage of Fabry disease in children and adolescents. Enzyme replacement therapy affects cardiac molecular remodeling after a single dose.

Cerebral blood flow in patients with Fabry disease as measured by Doppler sonography is not different from that in healthy individuals and is unaffected by treatment

OBJECTIVES

The purpose of this study was to investigate cervical and cerebral blood flow characteristics in patients with Fabry disease at baseline and under enzyme replacement therapy.

METHODS

In this case-control study we prospectively studied 68 patients with Fabry disease with extracranial and transcranial Doppler sonography. We compared extracranial and transcranial cervical and cerebral blood flow properties in all patients with Fabry disease and in subgroups of those with or without enzyme replacement therapy, male and female, and with normal or impaired renal function. Eight male patients were investigated at baseline and 1 year after initiation of enzyme replacement therapy.

RESULTS

We show that cervical and cerebral blood flow parameters in patients with Fabry disease are not different from normal values regardless of sex, renal function, or enzyme replacement therapy.

CONCLUSIONS

Cervical and cerebral blood flow measured with extracranial and transcranial Doppler sonography is not altered in patients with Fabry disease. Enzyme replacement therapy does not change blood flow characteristics.

The effectiveness of long-term agalsidase alfa therapy in the treatment of Fabry nephropathy

BACKGROUND AND OBJECTIVES

Fabry disease is a rare X-linked disease with multisystemic manifestations. This study investigated the effectiveness of long-term enzyme replacement therapy with agalsidase alfa in Fabry nephropathy treatment.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this observational study, data on patients receiving agalsidase alfa (0.2 mg/kg every other week) were extracted from the Fabry Outcome Survey, an international registry of patients with Fabry disease. Serum creatinine and estimated GFR (eGFR) at baseline and after ≥5 years of treatment were assessed; 24-hour urinary protein excretion and BP measurements were also reviewed. The eGFR was calculated using the Chronic Kidney Disease Epidemiology Collaboration formula. Patients with an eGFR <30 ml/min per 1.73 m(2) were excluded.

RESULTS

Renal function was assessed in 208 patients (mean enzyme replacement therapy, 7.4 years; range, 5.0-11.2 years). Mean yearly change in eGFR was -2.2 ml/min per 1.73 m(2) in men and -0.7 ml/min per 1.73 m(2) in women (95% confidence limits, -2.8; -1.7 and -1.4; 0.0, respectively). Patients with 24-hour protein excretion >1 g/24 h had poorer renal function at baseline and follow-up compared with patients with protein excretion of 500-1000 mg/24 h or with proteinuria <500 mg/24 h. Renal function was worse in patients with baseline arterial hypertension, and there was a more rapid yearly decline compared with normotensive patients.

CONCLUSIONS

This study suggests that long-term agalsidase alfa therapy is able to stabilize the rate of Fabry nephropathy progression in women and is associated with a mild to moderate decline of renal function in men.

Renal outcomes of agalsidase beta treatment for Fabry disease: role of proteinuria and timing of treatment initiation

BACKGROUND

The purpose of this study was to identify determinants of renal disease progression in adults with Fabry disease during treatment with agalsidase beta.

METHODS

Renal function was evaluated in 151 men and 62 women from the Fabry Registry who received agalsidase beta at an average dose of 1 mg/kg/2 weeks for at least 2 years. Patients were categorized into quartiles based on slopes of estimated glomerular filtration rate (eGFR) during treatment. Multivariate logistic regression analyses were used to identify factors associated with renal disease progression.

RESULTS

Men within the first quartile had a mean eGFR slope of -0.1 mL/min/1.73m(2)/year, whereas men with the most rapid renal disease progression (Quartile 4) had a mean eGFR slope of -6.7 mL/min/1.73m(2)/year. The risk factor most strongly associated with renal disease progression was averaged urinary protein:creatinine ratio (UP/Cr) ≥1 g/g (odds ratio 112, 95% confidence interval (95% CI) 4-3109, P = 0.0054). Longer time from symptom onset to treatment was also associated with renal disease progression (odds ratio 19, 95% CI 2-184, P = 0.0098). Women in Quartile 4 had the highest averaged UP/Cr (mean 1.8 g/g) and the most rapid renal disease progression: (mean slope -4.4 mL/min/1.73m(2)/year).

CONCLUSIONS

Adults with Fabry disease are at risk for progressive loss of eGFR despite enzyme replacement therapy, particularly if proteinuria is ≥1 g/g. Men with little urinary protein excretion and those who began receiving agalsidase beta sooner after the onset of symptoms had stable renal function. These findings suggest that early intervention may lead to optimal renal outcomes.

[Diagnosis of Fabry disease: usefulness of the clinical investigation]

Fabry disease, an X-linked lysosomal storage disorder due to alpha-galactosidase A deficiency, leads to an accumulation of globotriaosylceramide resulting in a multisystemic disorder. The initial manifestations of the disease are not specific, leading to a delayed diagnosis. We report a patient in whom the diagnosis was obtained by family screening and the confrontation of clinical signs. We also present a 4 year follow-up under enzyme replacement therapy (agalsidase β, 1 mg/kg/14 days).