Characterization of Classical and Nonclassical Fabry Disease: A Multicenter Study

Stratification of Fabry mutations in clinical practice: a closer look at α-galactosidase A-3D structure

BACKGROUND

Fabry disease (FD) is an X-linked lysosomal storage and multi-system disorder due to mutations in the α-galactosidase A (α-GalA) gene. We investigated the impact of individual amino acid exchanges in the α-GalA 3D-structure on the clinical phenotype of FD patients.

PATIENTS AND METHODS

We enrolled 80 adult FD patients with α-GalA missense mutations and stratified them into three groups based on the amino acid exchange location in the α-GalA 3D-structure: patients with active site mutations, buried mutations and other mutations. Patient subgroups were deep phenotyped for clinical and laboratory parameters and FD-specific treatment.

RESULTS

Patients with active site or buried mutations showed a severe phenotype with multi-organ involvement and early disease manifestation. Patients with other mutations had a milder phenotype with less organ impairment and later disease onset. α-GalA activity was lower in patients with active site or buried mutations than in those with other mutations (P < 0.01 in men; P < 0.05 in women) whilst lyso-Gb3 levels were higher (P < 0.01 in men; <0.05 in women).

CONCLUSIONS

The type of amino acid exchange location in the α-GalA 3D-structure determines disease severity and temporal course of symptom onset. Patient stratification using this parameter may become a useful tool in the management of FD patients.

Detection of novel Fabry disease-associated pathogenic variants in Japanese patients by newborn and high-risk screening

BACKGROUND

In Japan, newborn and high-risk screening for Fabry disease (FD), an inherited X-linked disorder caused by GLA mutations, using dried blood spots was initiated in 2006. In newborn screening, 599,711 newborns were screened by December 2018, and 57 newborns from 54 families with 26 FD-associated variants were detected. In high-risk screening, 18,235 individuals who had symptoms and/or a family history of FD were screened by March 2019, and 236 individuals from 143 families with 101 FD-associated variants were detected. Totally 3, 116 variants were detected; 41 of these were not registered in Fabry-database.org or ClinVar and 33 were definitely novel. Herein, we report the clinical outcomes and discuss the pathogenicity of the 41 variants.

METHODS

We traced nine newborns and 46 individuals with the 33 novel variants, and nine newborns and 10 individuals with eight other variants not registered in the FD database, and analyzed the information on symptoms, treatments, and outcomes.

RESULTS

Thirty-eight of the 46 individuals with the 33 novel variants showed symptoms and received enzyme-replacement therapy and/or chaperone treatment.

CONCLUSION

Delayed diagnosis should be avoided in patients with FD. Our results will help clinicians diagnose FD and determine the appropriate treatment for patients with these variants.

Fabry disease in India: A multicenter study of the clinical and mutation spectrum in 54 patients

Fabry disease (FD) is a treatable X linked lysosomal storage disorder with a wide phenotypic spectrum. There is a scarcity of published data on the burden of FD in India. This study evaluates the clinical and molecular spectrum of Indian patients with FD. In this multicentric study involving 10 tertiary referral centers in India, we analyzed the clinical course and genotype of 54 patients from 37 families. Family screening identified 19 new patients (35%) from 12 index cases. Then, 33 GLA gene variants were identified in 49/54 (90.7%) which included 11 novel and 22 known pathogenic variants. Of the 54 patients in our cohort, 40 patients had "classical" and 10 patients had a "nonclassical" presentation. The symptoms and signs included kidney dysfunction in 38/54 (70.3%), neuropathic pain in 34/54 (62.9%), left ventricular hypertrophy in 22/49 (44.8%) and stroke in 5/54 (9.2%). Female heterozygotes were 10/54 (18.5%) of whom 2 were index cases. There was a significant delay in reaching the diagnosis of 11.7 years. Enzyme replacement therapy was initiated in 28/54 (51.8%) patients with significant improvement of neuropathic pain and gastrointestinal symptoms. This study highlights the clinical presentation and mutational spectrum of FD in India and suggests that family screening and screening of high-risk groups (hypertrophic cardiomyopathy, idiopathic chronic renal failure and cryptogenic stroke) could be the most cost-effective strategies for early identification of FD.

Improvement of gastrointestinal symptoms in a significant proportion of male patients with classic Fabry disease treated with agalsidase beta: A Fabry Registry analysis stratified by phenotype

Background

Fabry disease is an inherited disorder of glycolipid metabolism with progressive involvement of multiple organs, including the gastrointestinal tract, in classically affected male patients. Clinical presentations in males with later-onset Fabry phenotypes are more heterogeneous and largely dependent on the level of residual α-galactosidase A activity.

Methods

We assessed agalsidase beta treatment outcomes of gastrointestinal symptoms in adult males with classic or later-onset Fabry disease. Self-reports of abdominal pain and diarrhea ('present'/'not present' since previous assessment) at last clinical visit (≥0.5 year of follow-up) were compared with treatment-baseline.

Results

Classic male patients were considerably younger at first treatment than the fewer males with later-onset phenotypes (36 vs. ~47 years) and reported gastrointestinal symptoms more frequently at baseline (abdominal pain: 56% vs. 13%; diarrhea: 57% vs. 23%). As compared with baseline, significantly fewer classic patients reported abdominal pain after a median of 4.7 years of treatment (N = 171, 56% vs. 41%, P < 0.001). Moreover, significantly fewer patients reported diarrhea after 5.5 years of follow-up (N = 169, 57% vs. 47%, P < 0.05). Among the males with later-onset phenotypes, albeit statistically non-significant, abdominal pain reports reduced after a median of 4.2 years (N = 48, 13% vs. 4%) and diarrhea reports reduced after a median of 4.4 years of treatment (N = 47, 23% vs. 13%).

Conclusions

Sustained treatment with agalsidase beta was associated with improvement in abdominal pain and diarrhea in a significant proportion of classic male Fabry patients. Males with later-onset phenotypes reported gastrointestinal symptoms much less frequently at baseline as compared with classic patients, and non-significant reductions were observed.

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.

Cardiac manifestations in patients with classical or cardiac subtype of Fabry disease

BACKGROUND

Fabry disease (FD) is an X-linked lysosomal storage disorder engendered by a deficiency of the enzyme α-galactosidase A, leading to systemic accumulation of glycolipids. Studies have reported that the cardiac subtype of FD has a later onset and minimal extracardiac involvement. However, whether the severity of cardiac involvement differs between the classic and cardiac subtypes of FD remains unclear.

METHODS

We enrolled consecutive patients with classic FD (n = 22; median age [25th-75th percentile], 47.0 [32.75-56.25] years; men, 72.7%) as well as age- and sex-matched patients with a later-onset cardiac subtype of FD who were selected from our cohort of patients with IVS4 919G>A mutation. FD was diagnosed on the basis of clinical symptoms/signs and pedigree screening of index case, plasma α-galactosidase activity, and molecular analysis. Data on clinical manifestations, laboratory findings, and echocardiogram findings were collected before enzyme replacement treatment. Disease severity was evaluated using the Mainz Severity Score Index score.

RESULTS

All female patients demonstrated heterozygous mutations, with five, one, and four of them showing normal α-galactosidase activity, classic FD, and cardiac subtype of FD, respectively. The distributions of left ventricular performance indices and comorbidities, including hypertension, diabetes mellitus, and dyslipidemia, were similar between the two groups. Moreover, MSSI cardiovascular scores did not differ significantly between the groups (classic vs cardiac subtype, 10.0 [2.0-12.5] vs 10.5 [9.0-15.25]; p = 0.277).

CONCLUSION

Cardiac manifestations are similar between patients with classic and cardiac subtype of FD.

Cognitive functioning and depressive symptoms in Fabry disease: A follow-up study

Patients with Fabry disease (FD) have a high prevalence of depressive symptoms and can suffer from cognitive impairment, negatively affecting their life. The course of cognitive functioning and depressive symptoms in FD is unknown. The aim of this prospective cohort study was to describe changes in cognitive functioning and depressive symptoms and to identify related variables in patients with FD over 1 year. Assessments were conducted twice, using a neuropsychological test battery and the Centre of Epidemiological Studies Depression scale (CESD). Eighty-one patients were included of which 76 patients (94%) completed both assessments (age: 44 years, 34% men, 75% classical phenotype). A significant decrease in cognitive functioning was found in four patients (5%), with patients regressing from excellent to average/good. Changes were not related to sex, phenotype, stroke, IQ or CESD scores. CESD scores ≥16 were present in 29 patients (38%) at baseline. Using the reliable change index a decrease in CESD scores was found in six patients (8%). Decreased CESD scores were independently related to employing a positive and problem solving coping style and increased CESD scores to an avoiding and brooding coping style and worsening health perception. We found no major changes in cognitive functioning in patients with FD during 1 year follow-up making it an unsuitable outcome in FD treatment trials. Considering the high prevalence of persistent depressive symptoms, assessment of depressive symptoms should be part of routine follow-up. Altering coping styles and health perception may improve psychological well-being in FD.

Variables Associated with Glomerular Hyperfiltration in Fabry Disease Patients

Background: Fabry disease is a genetic disorder caused by the deficiency of the lysosomal α-galactosidase A enzyme. This failure generates the storage of globotriaosylceramide in different cells with a progressive multi-organ involvement. Objectives: To report the prevalence of glomerular hyperfiltration in Fabry disease patients and the association with clinical variables. Methods: Adult patients (≥ 18 years) at the moment of FD diagnosis were evaluated. The variables studied were: central and peripheral nervous system compromise, presence of arterial hypertension, cardiac arrhythmia, left ventricular hypertrophy, albuminuria/proteinuria, cornea verticillata, gastrointestinal involvement, treatment with inhibitors of the renin-angiotensin-aldosterone system, deafness, and presence of angiokeratomas. Results: Forty-eight adults with Fabry disease (35.9 ± 11.7 years), 28 women (58.3%), and 20 men (41.7%) were analyzed. Nine (18.8%) patients with glomerular hyperfiltration, including six females and three males (mean age: 28.8 years), were detected. A significant association between and central nervous system (P = 0.021) and peripheral nervous system (P = 0.001) compromise, cardiac arrhythmia (P = 0.001), cornea verticillata (P = 0.009), and gastrointestinal involvement (P = 0.009) was observed. However, no association was found between glomerular hyperfiltration and proteinuria or treatment with inhibitors of the renin-angiotensin-aldosterone system. Conclusions: This research showed a higher prevalence of glomerular hyperfiltration in the younger group and a significant association between glomerular hyperfiltration and some typical manifestations of classic Fabry patients. Although more studies are needed, it is concluded that other mechanisms than glomerular hyperfiltration, like injury by glycosphingolipids deposit into the filtration barrier, might influence the protein loss in Fabry nephropathy.

Analysis of the alpha galactosidase gene: mutation profile and description of two novel mutations with extensive literature review in Turkish population

Objectives Fabry disease (FD, OMIM #301500) is a rare and progressive X-linked lysosomal storage disorder. FD is caused by mutations in the GLA gene on chromosome Xq22. Methods In this article, we aimed to present the largest sample of GLA mutation spectrum including common and novel variants in Turkish population. GLA gene sequence analysis was performed on the subjects who applied to the department of medical genetics with the preliminary diagnosis of FD between 2013 and 2018. Results We detected 22 different mutations as two novel [(p.F69S(c.206T>C), p.P205A (c.613C>G)] and 20 previously reported GLA mutations in 47 individuals from 22 unrelated families. These mutations included 14 missense mutations, four nonsense mutations, two small deletions, one small deletion/insertion and one small insertion. Major clinical findings of the female case with p.F69S(c.206T>C) mutation were cornea verticillata, acroparesthesia, angiokeratoma, psychiatric and gastrointestinal symptoms. Other novel mutation (p.P205A [c.613C>G]) was carried by a male case presenting gastrointestinal symptoms. Conclusions We described clinical findings of two cases that had novel mutations to provide more insight in genotype-phenotype correlation. We presented the largest mutation spectrum in Turkish population and reviewed previous mutations in this article.

Predicting the Development of Anti-Drug Antibodies against Recombinant alpha-Galactosidase A in Male Patients with Classical Fabry Disease

Fabry Disease (FD) is a rare, X-linked, lysosomal storage disease that mainly causes renal, cardiac and cerebral complications. Enzyme replacement therapy (ERT) with recombinant alpha-galactosidase A is available, but approximately 50% of male patients with classical FD develop inhibiting anti-drug antibodies (iADAs) that lead to reduced biochemical responses and an accelerated loss of renal function. Once immunization has occurred, iADAs tend to persist and tolerization is hard to achieve. Here we developed a pre-treatment prediction model for iADA development in FD using existing data from 120 classical male FD patients from three European centers, treated with ERT. We found that nonsense and frameshift mutations in the α-galactosidase A gene (p = 0.05), higher plasma lysoGb3 at baseline (p < 0.001) and agalsidase beta as first treatment (p = 0.006) were significantly associated with iADA development. Prediction performance of a Random Forest model, using multiple variables (AUC-ROC: 0.77) was compared to a logistic regression (LR) model using the three significantly associated variables (AUC-ROC: 0.77). The LR model can be used to determine iADA risk in individual FD patients prior to treatment initiation. This helps to determine in which patients adjusted treatment and/or immunomodulatory regimes may be considered to minimize iADA development risk.

[Diffuse hyperkeratotic papules of the lower abdomen and genital region in a 38-year old male patient]

A patient with diffuse angiokeratomas of the lower abdomen and genital region was diagnosed with Fabry disease on the basis of genetic testing. Fabry disease is an X-linked lysosomal storage disease that can affect several organ systems including the heart or kidneys, resulting in reduced median survival. Pathogenetically, Fabry disease leads to a deficiency of the lysosomal enzyme α‑galactosidase A (α-GAL A). Treatment options include lifelong enzyme replacement therapy or chaperone therapy.

Clinical course and pathological findings of two late-onset Fabry hemizygous patients including mulberry cell counts after enzyme replacement therapy

Fabry disease is an X-linked inherited lysosomal storage disorder caused by a deficiency of α-galactosidase A activity, resulting in the intracellular accumulation of globotriaosylceramide and related glycosphingolipids. The phenotypes of Fabry disease in both males and females are grouped into two categories: the classical type and the late-onset type. The classical type shows general symptoms including angiokeratoma(s), acroparesthesia, hypohidrosis, corneal opacity, and gastrointestinal symptoms from an early age. The late-onset type shows cardiac or renal (or both) symptoms from a late age. We present herein the clinical course and pathological findings of two late-onset hemizygous Fabry patients after the initiation of enzyme replacement therapy (ERT), along with their mulberry cell counts during treatment. One patient's case was a renal-variant type without general symptoms; he showed stable renal function and mild proteinuria but little histological improvement with no change in the mulberry cell count during ERT. The other patient had a cardiac-variant type with renal pathological abnormality. He achieved a mild improvement of renal pathological findings, and his mulberry cell count gradually decreased during the treatment. These findings indicate that monitoring the mulberry cell count might help assess the efficacy of ERT, as a renal pathology tool.

Oxidative stress biomarkers in Fabry disease: is there a room for them?

BACKGROUND

Fabry disease (FD) is an X-linked lysosomal storage disorder, caused by deficient activity of the alpha-galactosidase A enzyme leading to progressive and multisystemic accumulation of globotriaosylceramide. Recent data point toward oxidative stress signalling which could play an important role in both pathophysiology and disease progression.

METHODS

We have examined oxidative stress biomarkers [Advanced Oxidation Protein Products (AOPP), Ferric Reducing Antioxidant Power (FRAP), thiolic groups] in blood samples from 60 patients and 77 healthy controls.

RESULTS

AOPP levels were higher in patients than in controls (p < 0.00001) and patients presented decreased levels of antioxidant defences (FRAP and thiols) with respect to controls (p < 0.00001). In a small group of eight treatment-naïve subjects with FD-related mutations, we found altered levels of oxidative stress parameters and incipient signs of organ damage despite normal lyso-Gb3 levels.

CONCLUSIONS

Oxidative stress occurs in FD in both treated and naïve patients, highlighting the need of further research in oxidative stress-targeted therapies. Furthermore, we found that oxidative stress biomarkers may represent early markers of disease in treatment-naïve patients with a potential role in helping interpretation of FD-related mutations and time to treatment decision.

Rare Etiology of Renal Failure in a 25-Year-Old Caucasian Man: Fabry Disease With a Novel Mutation of GLA Gene

Fabry disease (FD) is an X-linked recessive lysosomal storage disease caused by a mutation of the galactosidase alpha (GLA) gene, leading to deficiency of α-galactosidase A (alpha-Gal A). This deficiency results in a progressive, multiorgan accumulation of glycolipids, most notably globotriaosylceramide (Gb3), leading to multiorgan failure and subsequently premature death. Gb3 accumulation in the podocytes, epithelial, and mesangial cells of the glomeruli results in progressive renal disease and eventually renal failure and hemodialysis (HD). There are two types of FD: early-onset classical type 1 and late-onset type 2. Although nearly a thousand mutations of the GLA gene have been identified, the majority of them are of unknown significance. Herein we report the case of a 25-year-old Caucasian male with no significant medical history who presented with peripheral neuropathy and end-stage renal failure, requiring HD. He was diagnosed with FD based on the electron microscopy findings of renal biopsy and severely reduced alpha-Gal A activity (<0.4 nmol/mL/hour). A novel mutation of c.281G>T; p.Cys94Phe was identified. On discharge from our facility, he was referred to a renal transplant center and genetic counseling.

When and How to Diagnose Fabry Disease in Clinical Pratice

Fabry disease is a frequent lysosomal storage disorder secondary to the deficiency of alpha-galactosidase A enzyme. This X-linked genetic disease realizes progressive and systemic manifestations that affect both male and female. Fabry disease may present as "classical", as "late-onset" or "non-classical" forms. Symptoms and organ involvements of classical Fabry disease are acral pain crisis, cornea verticillata, hypertrophic cardiomyopathy, stroke and chronic kidney disease with proteinuria. Other common symptoms are often poorly recognized, such as gastrointestinal or ear involvements. In classical Fabry disease, symptoms first appear during childhood or during teenage years in males, but later in females. Patients with non-classical or late-onset Fabry disease have delayed manifestations or a single-organ involvement. Diagnosis is therefore difficult when classical organ involvements are missing, in paucisymptomatic patients or in late-onset forms. Recognition of Fabry disease is important because effective treatments are available. They have to be prescribed early. In male, diagnosis is made with alpha-galactosidase A enzyme activity dosage in leukocyte, that is very low or null in classical forms and under 30 percent in late-onset forms. Diagnosis is more challenging in females who may express normal residual enzyme activity. Other plasmatic biomarkers, such as lyso-globotriaosylceramide are interesting, especially in females. In this review, we aimed to summarize main clinical manifestations of Fabry disease to know when to evoke Fabry disease and propose a practical diagnosis algorithm to know how to diagnose.

Genetic Management Algorithm in High-Risk Fabry Disease Cases; Especially in Female Indexes with Mutations

BACKGROUND

Fabry Disease (FD, OMIM#301500) is a progressive, life-threatening, multisystemic, rare lysosomal storage disease. Today, approximately 1000 mutations are recorded in the Human Gene Mutation Database (www.hgmd.org) for GLA. Among the identified mutations, genetic variants of unknown significance (GVUS) and novel mutations cause problems in terms of diagnosis and treatment approach.

METHODS

In our study, 510 high-risk patients were enrolled. 229 out of 510 were Male (45%) (Mean age was 40.8 ±15.0) and 281 of were Female (55%) (Mean age was 39, 7±15.5). The definite diagnosis of the FD was confirmed by GLA gene sequence analysis. GLA mutation was found in 15 cases (3.4%). Family members of the relevant indexes were included in the screening programs according to the X-linked inheritance pattern. And then we conducted family screening on 74 family members of 15 index cases. Of those 74 cases, 39 had mutations (53%). In males, α-GalA activity and in both gender Lyso-Gb3 levels were measured and multisystem evaluation was performed in all cases with the mutation.

RESULTS

We found six different familial mutation types; two of them pathogenic; p.D170N (1), p.P205S (13), one of them GVUS; p.Q330R (1), three of them likely benign; p.D313Y (12), p.S126G (25), c.-30G>A (2) mutations were detected.

CONCLUSION

The purpose of this retrospective study is to approach Fabry disease on a genetic basis and to improve its management and to draw attention to the importance of early diagnosis. We also aimed to evaluate the appropriate algorithms to determine whether the mutation is the FD-causing mutation or not.

Cornea Verticillata in classical Fabry disease, first from Sri Lanka: a case report

BACKGROUND

Fabry disease is a rare inborn error of metabolism with profound clinical consequences if untreated. It is caused by the deficiency of α galactosidase A enzyme and is the only lysosomal storage disorder with an X linked inheritance. Confirmation requires genetic analysis of Galactosidase Alpha (GLA) Gene, which is often a challenge in resource-poor settings. Despite these technological limitations, specific clinical features in this condition can establish the diagnosis.

CASE PRESENTATION

We report on a 13-year old male who presented with an afebrile convulsion with a background history of chronic burning sensation of hands and feet and anhidrosis for 2 years duration with a similar history of episodic acroparesthesia in the other male sibling. The early clinical diagnosis was based on the history and detection of Cornea Verticillata on eye examination. Biochemical confirmation was established with detection of low α galactosidase A enzyme levels and a missense mutation of the Galactosidase Alpha (GLA) Gene (c.136C > T) established the genetic confirmation.

CONCLUSION

This is the first case of Fabry disease reported in Sri Lanka. Awareness of specific clinical features aided clinical diagnosis long before access to genetic confirmation was available.

Determinants of cerebral radiological progression in Fabry disease

BACKGROUND AND AIM

It is unclear which patients with Fabry disease (FD) are at risk for progression of white matter lesions (WMLs) and brain infarctions and whether enzyme replacement therapy (ERT) changes this risk. The aim of this study was to determine the effect of ERT and clinical characteristics on progression of WMLs and infarctions on MRI in patients with FD.

METHODS

MRIs were assessed for WMLs (Fazekas scale), infarctions and basilar artery diameter (BAD). The effect of clinical characteristics (renal and cardiac involvement, cardiovascular risk factors, cardiac complications, BAD) and ERT on WML and infarction progression was evaluated using mixed models.

RESULTS

One hundred forty-nine patients were included (median age: 39 years, 38% men, 79% classical phenotype). Median follow-up time was 7 years (range: 0-13 years) with a median number of MRIs per patient of 5 (range: 1-14), resulting in a total of 852 scans. Variables independently associated with WML and infarction progression were age, male sex and a classical phenotype. Progression of WMLs and infarctions was not affected by adding ERT to the model, neither for the whole group, nor for early treated patients. Progression was highly variable among patients which could not be explained by other known variables such as hypertension, cholesterol, atrial fibrillation and changes in kidney function, left ventricular mass or BAD.

CONCLUSION

Progression of WMLs and cerebral infarctions in FD is mainly related to age, sex and phenotype. Additional effects of established cardiovascular risk factors, organ involvement and treatment with ERT are probably small to negligible.

Fabry disease due to G171S GLA mutation: An atypical small nerve fiber sparing variant?

INTRODUCTION

To describe the ocular manifestations and in vivo confocal microscopic findings in a patient carrying the recently described hemizygous G171S GLA gene mutation.

CASE DESCRIPTION

A 63-year-old Albanian male patient was evaluated for cataract surgery. Anamnesis showed pacemaker implantation in left ventricular hypertrophy, chronic kidney disease, family history for kidney transplantation, and late onset of sporadic acroparesthesias. Bilateral cornea verticillata, and increased tortuosity in conjunctival and retinal vessels were present. In vivo confocal microscopy revealed clusters of hyper-reflective corneal epithelial cells centripetally extending from the limbus. Interestingly, the nerve fiber number, density, and length in the corneal sub-basal nerve plexus were preserved. Alpha-galactosidase A activity was almost absent and hemizygous c.511G>A mutation (G171S - p.Gly171Ser) of the GLA gene was identified. The patient was referred for initiation of enzyme replacement therapy, and genetic counseling was recommended for at-risk family members.

CONCLUSION

This is the third reported case of Fabry disease due to GLA G171S mutation. All patients are of Albanian descent. Cornea verticillata and vascular anomalies remain common ocular manifestations, as well as cardiac and renal involvement. Confirming its pathogenicity, this mutation results in a "classic" Fabry disease phenotype, but it seems to be associated with a relative small nerve fiber sparing that may delay a correct diagnosis. The diagnosis of Fabry disease still remains challenging due to its clinical heterogeneity, but a thorough ophthalmological examination can promote early detection and, consequently, early initiation of enzyme replacement therapy.

Kidney Transplant in Fabry Disease: A Revision of the Literature

Fabry disease is classified as a rare X-linked disease caused by a complete or partial defect of enzyme alpha-galactosidase, due to GLA gene mutations. This disorder leads to intracellular globotriaosylceramide (Gb3) deposition associated with increased Gb3 plasma levels. Most of the symptoms of the disease, involving kidneys, heart and nervous system, result from this progressive Gb3 deposition. The incidence is estimated in 1/50,000 to 1/117,000 in males. Fabry nephropathy begins with microalbuminuria and/or proteinuria, which, in the classic form, appear from childhood. Thus, a progressive decline of renal function can start at a young age, and evolve to kidney failure, requiring dialysis or renal transplantation. Enzyme replacement therapy (ERT), available since 2001 for Fabry disease, has been increasingly introduced into the clinical practice, with overall positive short-term and long-term effects in terms of ventricular hypertrophy and renal function. Kidney transplantation represents a relevant therapeutic option for Fabry nephropathy management, for patients reaching end-stage renal disease, but little is known about long-term outcomes, overall patient survival or the possible role of ERT after transplant. The purpose of this review is to analyze the literature on every aspect related to kidney transplantation in patients with Fabry nephropathy: from the analysis of transplant outcomes, to the likelihood of disease recurrence, up to the effects of ERT and its possible interference with immunosuppression.

Analysis of Renal and Cardiac Outcomes in Male Participants in the Fabry Outcome Survey Starting Agalsidase Alfa Enzyme Replacement Therapy Before and After 18 Years of Age

Purpose

To determine the impact of initiating enzyme replacement therapy (ERT) with agalsidase alfa early in the course of Fabry disease, we evaluated renal and cardiac outcomes for ≤10 years after ERT initiation in males from the Fabry Outcome Survey (FOS).

Patients and Methods

Male patients from FOS were stratified into three cohorts by age at ERT initiation: ≤18 years (cohort 1), >18 and ≤30 years (cohort 2), and >30 years (cohort 3). Analysis included age at symptom onset, diagnosis, and ERT initiation; ERT duration; FOS-Mainz Severity Score Index (FOS-MSSI); estimated glomerular filtration rate (eGFR); proteinuria level; and left ventricular mass indexed to height (LVMI). Mixed-effect models estimated renal and cardiac outcomes during follow-up between and within cohorts.

Findings

The analysis included 560 male patients: 151 (27.0%) in cohort 1, 155 (27.7%) in cohort 2, and 254 (45.4%) in cohort 3. Mean±SD duration of ERT for cohorts 1, 2, and 3 was 6.3±4.3, 8.6±4.9, and 7.9±4.9 years, respectively. Mean±SD baseline FOS-MSSI scores increased with age from 9.8±7.2 in cohort 1 to 24.7±11.4 in cohort 3. Cohort 3 showed the lowest baseline mean±SD value for eGFR (87.1±29.0 mL/min/1.73m²) and highest baseline mean±SD values for proteinuria (801.9±952.6 mg/day) and LVMI (56.7±16.0 g/m^2.7) among the three cohorts. Evaluation of mean annual rates of change in eGFR, proteinuria, and LVMI revealed no significant differences in any parameter for cohort 1. For cohort 2, proteinuria and LVMI remained stable, whereas eGFR significantly deteriorated annually (–1.12 mL/min/1.73m²; P<0.001). Cohort 3 demonstrated significant annual deteriorations in eGFR (–2.60 mL/min/1.73m²; P<0.001), proteinuria (+34.10 mg/day; P<0.001), and LVMI (+0.59 g/m^2.7; P=0.001).

Implications

Renal and/or cardiac disease progression appears attenuated in patients starting ERT in childhood or early adulthood versus patients starting ERT in later adulthood. These findings support early ERT initiation in Fabry disease. ClinicalTrials.gov identifier: NCT03289065.

Cornea verticillata and acroparesthesia efficiently discriminate clusters of severity in Fabry disease

BACKGROUD

Fabry disease (OMIM #301 500), the most prevalent lysosomal storage disease, is caused by enzymatic defects in alpha-galactosidase A (GLA gene; Xq22.1). Fabry disease has historically been characterized by progressive renal failure, early stroke and hypertrophic cardiomyopathy, with a diminished life expectancy. A nonclassical phenotype has been described with an almost exclusive cardiac involvement. Specific therapies with enzyme substitution or chaperone molecules are now available depending on the mutation carried. Numerous clinical and fundamental studies have been conducted without stratifying patients by phenotype or severity, despite different prognoses and possible different pathophysiologies. We aimed to identify a simple and clinically relevant way to classify and stratify patients according to their disease severity.

METHODS

Based on data from the French Fabry Biobank and Registry (FFABRY; n = 104; 54 males), we applied unsupervised multivariate statistics to determine clusters of patients and identify clinical criteria that would allow an effective classification of adult patients. Thanks to these criteria and empirical clinical considerations we secondly elaborate a new score that allow the severity stratification of patients.

RESULTS

We observed that the absence of acroparesthesia or cornea verticillata is sufficient to classify males as having the nonclassical phenotype. We did not identify criteria that significantly cluster female patients. The classical phenotype was associated with a higher risk of severe renal (HR = 35.1; p <10-3) and cardiac events (HR = 4.8; p = 0.008) and a trend toward a higher risk of severe neurological events (HR = 7.7; p = 0.08) compared to nonclassical males. Our simple, rapid and clinically-relevant FFABRY score gave concordant results with the validated MSSI.

CONCLUSION

Acroparesthesia and cornea verticillata are simple clinical criteria that efficiently stratify Fabry patients, defining 3 different groups: females and males with nonclassical and classical phenotypes of significantly different severity. The FFABRY score allows severity stratification of Fabry patients.

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.

A Proteomics-Based Analysis Reveals Predictive Biological Patterns in Fabry Disease

Background: Fabry disease (FD) is an X-linked progressive lysosomal disease (LD) due to glycosphingolipid metabolism impairment. Currently, plasmatic globotriaosylsphingosine (LysoGb3) is used for disease diagnosis and monitoring. However, this biomarker is inconstantly increased in mild forms and in some female patients. Materials and Methods: We applied a targeted proteomic approach to explore disease-related biological patterns that might explain the disease pathophysiology. Forty proteins, involved mainly in inflammatory and angiogenesis processes, were assessed in 69 plasma samples retrieved from the French Fabry cohort (FFABRY) and from 83 healthy subjects. For predictive performance assessment, we also included other LD samples (Gaucher, Pompe and Niemann Pick C). Results: The study yielded four discriminant proteins that include three angiogenesis proteins (fibroblast growth factor 2 (FGF2), vascular endothelial growth factor A (VEGFA), vascular endothelial growth factor C (VEGFC)) and one cytokine interleukin 7 (IL-7). A clear elevation of FGF2 and IL-7 concentrations was observed in FD compared to other LD samples. No correlation was observed between these proteins and globotriaosylsphingosine (LysoGb3). A significant correlation exists between IL-7 and residual enzyme activity in a non-classical phenotype. This highlights the orthogonal biological information yielded by these proteins that might help in stratifying Fabry patients. Conclusion: This work highlights the potential of using proteomics approaches in exploring FD and enhancing FD diagnosis and therapeutic monitoring performances.

New drugs for the treatment of Anderson-Fabry disease

Enzyme replacement therapy (ERT) of the Anderson-Fabry disease (AFD) has changed the outcome of patients. However, ERT has some limitations: a restricted volume of distribution, requirement for intravenous access, and stimulation of the production of anti-drug antibodies. Studies of new drugs aiming to improve the clinical effectiveness and convenience of therapy have been reported. Migalastat, a pharmacological chaperone, increases available enzymate activity in patients with mutations amenable to the therapy, is now available for clinical practice. It is orally administered, and while clinical trial results are promising, long term real world follow up is awaited. PEGylated enzyme has a longer half-life and potentially reduced antigenicity, compared with standard preparations; investigation of whether a longer dosing interval is viable is under way. Moss-derived enzyme has a higher affinity for mannose receptors, and appears to have access to renal tissue. Substrate reduction therapy is based on reducing the catabolism processes of the glycosphingolipids, and is currently under investigation as monotherapy. Gene therapy has now been initiated in clinical trail of in vivo and ex vivo technologies with early results are emerging. ERT represents a certain milestone of therapy for AFD with Migalastat now a newly available option. Other agents in clinical trial prevent further potential opportunities to improve outcomes in AFD.

Use of a rare disease registry for establishing phenotypic classification of previously unassigned GLA variants: a consensus classification system by a multispecialty Fabry disease genotype-phenotype workgroup

BACKGROUND

Fabry disease (α-galactosidase deficiency) is an X-linked genetic disease caused by a variety of pathogenic GLA variants. The phenotypic heterogeneity is considerable, with two major forms, classic and later-onset disease, but adjudication of clinical phenotype is currently lacking for many variants. We aimed to determine consensus phenotypic classification for previously unclassified GLA variants from the GLA-specific fabry-database.org database.

METHODS

A Fabry disease genotype-phenotype workgroup developed a five-stage iterative system based on expert clinical assessment, published literature and clinical evidence of pathogenicity using a 2-point scoring system based on clinical hallmarks of classic disease. Kaplan-Meier (KM) analysis of severe clinical event-free survival was used as final validation. Results were compared with those from web-based disease databases and in silico pathogenicity prediction programmes.

RESULTS

Final consensus on classifications of 'pathogenic' was achieved for 32 of 33 GLA variants (26 'classic' phenotype, 171 males; 6 'later-onset' phenotype, 57 males). One variant remained of uncertain significance. KM curves were similar for the known fabry-database.org database phenotypes and when workgroup consensus classifications were added, and the curves retained the same separation between 'classic' and 'later-onset' phenotypes.

CONCLUSION

The iterative system implemented by a Fabry disease genotype-phenotype workgroup achieved phenotypic classifications for variants that were previously unclassified. Clinical pathogenicity associated with a particular GLA variant defined in affected males appears to have predictive value and also generally correlates with risk for affected females. The newly established classifications can be of benefit to the clinical care of Fabry patients harbouring these variants.

Natural history of the late-onset phenotype of Fabry disease due to the p.F113L mutation

BACKGROUND

The common GLA gene mutation p.F113L causes late-onset phenotype of Fabry disease (FD) with predominant cardiac manifestations. A founder effect of FD due to this mutation was found in the Portuguese region of Guimarães. Our study aims to deepen the knowledge on the natural history of this late-onset variant.

METHODS

203 consecutive adult Fabry patients with p.F113L mutation (79 males; mean age 46 ± 18 years), from this region, were submitted at baseline to a predefined diagnostic protocol. The occurrence of FD manifestations was analyzed in each decade of age in both genders.

RESULTS

In males, left ventricular hypertrophy (40.2%) and late gadolinium enhancement (21.4%) arose over 30 years; heart failure (HF) (21.9%), ventricular tachycardia (8.9%) and conduction disorders over 40 years; and bifascicular (13.1%) and complete atrioventricular blocks (5.9%) beyond 50 years of age. Cardiac manifestations occurred more commonly and 1-2 decades earlier in males; their frequency increased with age. Septum and posterior wall thickness, LV mass, QRS interval duration and pro-BNP levels increased with age in both genders. Mean survival free from HF (64 ± 1 vs. 76 ± 2 years) and pacemaker (71 ± 2 vs. 86 ± 1 years) was higher in females (p < .001). Albuminuria A2/A3 (33.7%), brain white matter lesions (50.3%) and sensorineural deafness (44.7%) arose before 30 years of age in both genders, increasing with age. Renal failure and stroke were rare. Lysosomal inclusions were demonstrated in podocytes of patients with proteinuria.

CONCLUSION

This study improves the knowledge on natural history of late-onset variants of FD, carrying major impact on clinical decisions and guidelines.

Cardiomyopathy and kidney function in agalsidase beta-treated female Fabry patients: a pre-treatment vs. post-treatment analysis

AIMS

Long-term treatment effect studies in large female Fabry patient groups are challenging to design because of phenotype heterogeneity and lack of appropriate comparison groups, and have not been reported. We compared long-term cardiomyopathy and kidney function outcomes after agalsidase beta treatment with preceding treatment-naive outcomes.

METHODS AND RESULTS

Self-controlled pretreatment and post-treatment comparison (piecewise mixed linear modelling) included Fabry female patients ≥18 years at treatment initiation who received agalsidase beta (0.9-1.1 mg/kg every other week) for ≥2 years, with ≥2 pretreatment and ≥2 post-treatment outcome measurements during 10-year follow-up. Left ventricular posterior wall thickness (LVPWT)/interventricular septal thickness (IVST) and estimated glomerular filtration rate (eGFR, Chronic Kidney Disease Epidemiology Collaboration creatinine equation) analyses included 42 and 86 patients, respectively, aged 50.0 and 46.3 years at treatment initiation, respectively. LVPWT and IVST increased pretreatment (follow-up 3.5 years) but stabilized during 3.6 years of treatment (LVPWT: n = 38, slope difference [95% confidence interval (CI)] = -0.41 [-0.68, -0.15] mm/year, P_{pre-post difference}  <0.01; IVST: n = 38, slope difference = -0.32 [-0.67, 0.02] mm/year, P_{pre-post difference}  = 0.07). These findings were not modified by renal involvement or antiproteinuric agent use. Compared with the treatment-naive period (follow-up 3.6 years), eGFR decline remained modest and stabilized within normal ranges during 4.1 years of treatment (slope difference, 95% CI: -0.13 [-1.15, 0.89] mL/min/1.73m² /year, P_{pre-post difference}  = 0.80).

CONCLUSIONS

Cardiac hypertrophy, progressing during pretreatment follow-up, appeared to stabilize during sustained agalsidase beta treatment. eGFR decline remained within normal ranges. This suggests that treatment may prevent further Fabry-related progression of cardiomyopathy in female patients and maintain normal kidney function.

Pathogenesis of Fabry nephropathy: The pathways leading to fibrosis

BACKGROUND

Kidney is one of the main target organs in Fabry disease, a lysosomal X-linked genetic disorder. Renal involvement is characterized by proteinuria and progressive chronic kidney disease leading to end-stage renal disease. Pathogenic mechanisms in the progression of renal damage in Fabry disease are not thoroughly known yet. The lysosomal Gb3 deposition is the first step of complex pathological pathways resulting in renal sclerosis/fibrosis. Our hypothesis is that Fabry disease associated cellular alterations in tubular cells induce the production of TGF-β1, which mediate transdifferentiation of renal cells into myofibroblasts resulting in fibrosis of renal tissue.

OBJECTIVES

The aim of this work is to study the mechanisms leading to fibrosis in kidney from human Fabry patients.

METHODS

Fifteen renal biopsies from naïve Fabry patients were included. Histological and immunohistochemical analysis was carried out.

RESULTS

Positive staining for TGF-β1 was found in tubular epithelial cells in biopsies from Fabry patients. Apoptosis was determined by active caspase 3 staining in tubular and mesangial glomerular cells. Due to TGF-β1 is the main profibrotic cytokine and induces accumulation of myofibroblasts, we performed a study for its marker α-smooth muscle actin (α-SMA). This study revealed expression of α-SMA on pericytes surrounding peritubular capillaries, smooth muscle cells of blood vessels, mesangial cells and periglomerular zone. TGF-β1 is produced mainly by tubular cells in Fabry kidney biopsies probably inducing cellular trans-differentiation of renal cells into myofibroblasts. A positive staining for a marker of myofibroblasts was present, affirming the presence of those profibrotic cells.

CONCLUSIONS

These results show for the first time that TGF-β1 is expressed in human renal tissue from Fabry patients, and that this profibrotic cytokine is mainly produced by proximal tubular cells. In addition both, peritubular interstitium and glomeruli, presented cells positive for myofibroblasts markers.

Depressive symptoms in Fabry disease: the importance of coping, subjective health perception and pain

Background

Despite the high prevalence of depressive symptoms in Fabry disease (FD), it is unclear which patient characteristics are important in relation to these symptoms. Additionally, the impact of coping styles in relation to depressive symptoms in FD has been unexplored. Determining the impact of different factors relating to depressive symptoms in FD can guide both prevention and treatment of these symptoms.

Methods

Depressive symptoms (Center for Epidemiologic Studies Depression scale (CESD)) and coping styles (Utrecht Coping List) were assessed in a Dutch FD cohort. Other potentially important variables were identified from FD literature and assessed in this cohort. Relations were evaluated using multiple linear models.

Results

Potentially important variables in FD literature were: pain, unemployment, health perception, being single, comorbidities and stroke. Employed coping styles were “avoidance and brooding”, “positivity and problem solving” and “seeking social support”. Thirty-one of the 81 FD patients (38%) had depressive symptoms. CESD-scores were lower in patients with better health perception and more “positivity and problem solving” and higher in patients with more pain and “avoidance and brooding”. The best model explained 70% (95%CI: 54–76%) of observed variance of the CESD.

Conclusions

Depressive symptoms in FD are related to pain, negative health perception and use of specific coping styles. Psychological interventions could be employed to alter coping behavior and alleviate depressive symptoms.

Migalastat: A Review in Fabry Disease

Fabry disease is a rare lysosomal disorder characterized by deficient or absent α-galactosidase A activity resulting from mutations in the GLA gene. Migalastat (Galafold™), a pharmacological chaperone, stabilizes and facilitates trafficking of amenable mutant forms of α-galactosidase A enzyme from the endoplasmic reticulum to lysosomes and increases its lysosomal activity. Oral migalastat is the first pharmacological chaperone approved for treating patients [aged ≥ 18 years (USA and Canada) or ≥ 16 years in other countries] with Fabry disease who have a migalastat-amenable GLA mutation. In the FACETS trial in enzyme replacement therapy (ERT)-naive patients with GLA mutations amenable or non-amenable to migalastat, there was no significant difference between the migalastat and placebo groups for the proportion of patients achieving a ≥ 50% reduction in the number of globotriaosylceramide (GL-3) inclusions/kidney interstitial capillary (KIC) at 6 months [primary endpoint; intent-to-treat (ITT) population]. In the modified ITT population (i.e. patients with migalastat-amenable GLA mutations), relative to placebo, migalastat treatment significantly reduced the mean number of GL-3 inclusions/KIC and plasma lyso-globotriaosylsphingosine levels at 6 months. Among evaluable patients, migalastat maintained renal function and reduced cardiac mass after ≤ 24 months’ therapy. In the ATTRACT trial in ERT-experienced patients, renal function was maintained during 18 months of migalastat or ERT; however, migalastat significantly reduced cardiac mass compared with ERT. Migalastat was generally well tolerated in both of these trials. Given its convenient oral regimen and the limited therapeutic options available, migalastat is an important treatment option for Fabry disease in patients with migalastat-amenable GLA mutations.

Globotriaosylceramide-induced reduction of KCa1.1 channel activity and activation of the Notch1 signaling pathway in skin fibroblasts of male Fabry patients with pain

BACKGROUND

Fabry disease (FD) is an X-linked lysosomal storage disorder that leads to cellular globotriaosylceramide (Gb3) accumulation due to mutations in the gene encoding α-galactosidase A. Trigger-induced acral burning pain is an early FD symptom of unknown pathophysiology. We aimed at investigating the potential role of skin fibroblasts in nociceptor sensitization.

PATIENTS AND METHODS

We enrolled 40 adult FD patients and ten healthy controls, who underwent a 6-mm skin punch biopsy at the lower leg. Dermal fibroblasts were cultivated and analyzed for Gb3 load. Fibroblast electrical activity was assessed using patch-clamp analysis at baseline and upon incubation with agalsidase-α for 24 h. We investigated gene expression of CC motif chemokine ligand 2 (CCL2), Ca²⁺activated K⁺-channel 1.1 (K_Ca1.1), interferone-γ (IFN-γ), transforming growth factor-β1 (TGF-β1), and transmembrane receptor notch homolog 1 (Notch1) using quantitative real-time-PCR, and protein levels of K_Ca1.1 by ELISA. Gene expression was determined at baseline and after fibroblast stimulation with tumor necrosis factor-α (TNF), modeling inflammation as a common pain trigger in FD.

RESULTS

Total Gb3 load was higher in FD fibroblasts than in control fibroblasts (p < .01). Upon increase of intracellular Ca²⁺ concentrations, we detected differential electrical activity of K_Ca1.1 in fibroblasts obtained from patients with FD. Gene expression (p < .05) and protein levels of K_Ca1.1 (p < .05) were higher in fibroblasts from FD patients compared to control fibroblasts, whereas electric channel activity was lower in FD fibroblasts. After incubation with agalsidase-α, we observed an over-proportionate increase of K_Ca1.1 activity in FD fibroblasts reaching 7-fold the currents of control cells (p < .01). Gene expression studies revealed higher mRNA levels of CCL2, INF-γ, and Notch1 in FD fibroblasts compared to controls at baseline and after TNF incubation (p < .05 each), while TGF-β1 was higher in FD fibroblasts only after incubation with TNF (p < .05).

CONCLUSIONS

Gb3 deposition in skin fibroblasts may impair K_Ca1.1 activity and activate the Notch1 signaling pathway. The resulting increase in pro-inflammatory mediator expression may contribute to cutaneous nociceptor sensitization as a potential mechanism of FD-associated pain.

Symptoms and Quality of Life in Patients with Fabry Disease: Results from an International Patient Survey

INTRODUCTION

Fabry disease is an X-linked lysosomal storage disorder caused by a deficiency of α-galactosidase A. Symptoms include neuropathic pain and gastrointestinal problems, such as diarrhoea. To inform and support the design of a Phase III clinical trial for a new oral treatment for Fabry disease, this study evaluated patients' experiences of Fabry disease symptoms, the impact of symptoms on their quality of life, and their views on participating in clinical trials.

METHODS

An online survey questionnaire was distributed to patients with Fabry disease, through relevant patient organisations. The questionnaire consisted mainly of quantitative, closed questions with pre-defined response options. Fabry-specific pain intensity and its impact on quality of life were rated on a scale from 0 to 10.

RESULTS

In total, 367 patients completed the survey, of whom half reported frequent pain, moderate to severe pain, and pain in their hands and feet. Pain frequency, intensity and location were similar for males and females. There was no clear association between Fabry-specific pain and the use of enzyme replacement therapy (ERT), with moderate to severe pain reported by 80.4% of participants receiving ERT and by 75.0% of participants not receiving ERT. Of participants who were receiving ERT, 35.7% said they were willing to discontinue it to take part in a clinical trial testing a new oral drug for treating Fabry disease. Gastrointestinal symptoms were more heterogeneous in nature and frequency than Fabry-specific pain, but still affected a significant proportion of participants.

CONCLUSIONS

Both male and female patients with Fabry disease experience significant Fabry-specific pain, which affects their quality of life. Furthermore, frequent diarrhoea affects many patients. The symptoms occur independently of the use of ERT. This suggests the healthcare needs of patients with Fabry disease are not being fully met, and additional treatments are required to improve symptoms and quality of life.

FUNDING

This study was sponsored by Actelion Pharmaceuticals Ltd. Study sponsorship was transferred to Idorsia Pharmaceuticals Ltd in July 2018.

Renal globotriaosylceramide deposits for Fabry disease linked to uncertain pathogenicity gene variant c.352C>T/p.Arg118Cys: A family study

Background

Fabry disease (FD) has an extensive phenotypic expression associated with GLA gene variants. The GLA gene variant c.352C>T/p.Arg118Cys was considered with uncertain pathogenicity because of the finding of high residual alpha‐galactosidase A (α‐Gal A) enzyme activity, the absence of Mendelian segregation with an FD phenotype with many individuals remaining asymptomatic at old ages and the lack of globotriaosylceramide (Gb3) deposits in tissues. Gb3 deposits are found in kidneys before the progression to overt microalbuminuria and decreased glomerular filtration.

Methods

We describe a family with c.352C>T/p.Arg118Cys variant and pathognomonic signs of FD renal damage in masculine children.

Results

The proband died of end‐stage renal failure and we analyzed GLA gene in his offspring and found the variant in all daughters and five of seven grandchildren. In patients who we measure plasma and urinary Gb3, α‐Gal A enzyme activity, and plasma globotriaosylsphingosine (Lyso‐Gb3), these were normal or almost normal. A kidney biopsy was performed in two boys and one girl with normal renal function and characteristic signs of FD as enlarged and vacuolated epithelial cells, myelin figures, myelin‐like figures, lamellated structures in podocytes and endothelial cells, were found in boys. These boys received agalsidase beta 1 mg/kg IV infusion every other week to prevent further renal damage.

Conclusion

This is the first report that shows a link between FD renal Gb3 deposits and c.352C>T/p.Arg118Cys variant, supporting pathogenicity of a variant considered until now with uncertain pathogenicity.

Rapid, proteomic urine assay for monitoring progressive organ disease in Fabry disease

BACKGROUND

Fabry disease is a progressive multisystemic disease, which affects the kidney and cardiovascular systems. Various treatments exist but decisions on how and when to treat are contentious. The current marker for monitoring treatment is plasma globotriaosylsphingosine (lyso-Gb3), but it is not informative about the underlying and developing disease pathology.

METHODS

We have created a urine proteomic assay containing a panel of biomarkers designed to measure disease-related pathology which include the inflammatory system, lysosome, heart, kidney, endothelium and cardiovascular system. Using a targeted proteomic-based approach, a series of 40 proteins for organ systems affected in Fabry disease were multiplexed into a single 10 min multiple reaction monitoring Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS) assay and using only 1 mL of urine.

RESULTS

Six urinary proteins were elevated in the early-stage/asymptomatic Fabry group compared with controls including albumin, uromodulin, α1-antitrypsin, glycogen phosphorylase brain form, endothelial protein receptor C and intracellular adhesion molecule 1. Albumin demonstrated an increase in urine and could indicate presymptomatic disease. The only protein elevated in the early-stage/asymptomatic patients that continued to increase with progressive multiorgan involvement was glycogen phosphorylase brain form. Podocalyxin, fibroblast growth factor 23, cubulin and Alpha-1-Microglobulin/Bikunin Precursor (AMBP) were elevated only in disease groups involving kidney disease. Nephrin, a podocyte-specific protein, was elevated in all symptomatic groups. Prosaposin was increased in all symptomatic groups and showed greater specificity (p<0.025-0.0002) according to disease severity.

CONCLUSION

This work indicates that protein biomarkers could be helpful and used in conjunction with plasma lyso-Gb3 for monitoring of therapy or disease progression in patients with Fabry disease.

Genetic Factors of Cerebral Small Vessel Disease and Their Potential Clinical Outcome

Cerebral small vessel diseases (SVD) have been causally correlated with ischemic strokes, leading to cognitive decline and vascular dementia. Neuroimaging and molecular genetic tests could improve diagnostic accuracy in patients with potential SVD. Several types of monogenic, hereditary cerebral SVD have been identified: cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL), cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), cathepsin A-related arteriopathy with strokes and leukoencephalopathy (CARASAL), hereditary diffuse leukoencephalopathy with spheroids (HDLS), COL4A1/2-related disorders, and Fabry disease. These disorders can be distinguished based on their genetics, pathological and imaging findings, clinical manifestation, and diagnosis. Genetic studies of sporadic cerebral SVD have demonstrated a high degree of heritability, particularly among patients with young-onset stroke. Common genetic variants in monogenic disease may contribute to pathological progress in several cerebral SVD subtypes, revealing distinct genetic mechanisms in different subtype of SVD. Hence, genetic molecular analysis should be used as the final gold standard of diagnosis. The purpose of this review was to summarize the recent discoveries made surrounding the genetics of cerebral SVD and their clinical significance, to provide new insights into the pathogenesis of cerebral SVD, and to highlight the possible convergence of disease mechanisms in monogenic and sporadic cerebral SVD.

The clinical profiles of female patients with Fabry disease in Latin America: A Fabry Registry analysis of natural history data from 169 patients based on enzyme replacement therapy status

BACKGROUND

Fabry disease is an X-linked lysosomal storage disorder with heterogeneous clinical expression in female patients ranging from asymptomatic to severe clinical presentations as in classic males. We assessed clinical profiles and compared natural history data of female patients eventually initiated on enzyme replacement therapy ("ERT-recipients") with those remaining untreated ("ERT-naïve").

METHODS

We analyzed Fabry Registry data from 93 ERT-recipients, collected prior to ERT initiation, and 76 ERT-naïve females with classic or unclassified phenotypes from four Latin American countries and evaluated Fabry symptoms, interventricular septum thickness, left ventricular posterior wall thickness, estimated glomerular filtration rate, and severe clinical events.

RESULTS

For 169 patients with available data, median age of first Fabry symptom manifestation was 12.7 years with peripheral pain as predominant first symptom, and diagnostic delay of 10.3 years from the first reported symptom. Female patients had high symptomatic burden during natural history follow-up, with 83% reporting peripheral pain, 69%-79% cold/heat intolerance or abnormal sweating, and 32% gastrointestinal symptoms. ERT-recipients reported similar age at first symptom as ERT-naïve patients but they were older at diagnosis (median 39.2 vs 24.4 years, P < .01) and last follow-up (median 43.4 vs 28.2 years, P < .01). Reported Fabry symptom frequencies and abnormal echocardiography findings were higher in ERT-recipients. Functional renal assessments were normal and similar.

CONCLUSIONS

Female patients from Latin America have notable diagnostic delays and high symptomatic burden. ERT was prescribed late in females with advanced age at diagnosis and advanced disease. There remained many female patients who had been diagnosed at younger age, had substantial Fabry manifestations, but did not receive disease-specific treatment.

Natural course of Fabry disease with the p. Arg227Ter (p.R227*) mutation in Finland: Fast study

Background

Fabry disease is caused by a deficient or an absent alfa‐galactosidase A activity and is an X‐linked disorder that results in organ damage and a shortened life span, especially in males. The severity of the disease depends on the type of mutation, gender, skewed X‐chromosome inactivation, and other still unknown factors.

Methods

In this article, we describe the natural course of a common classic Fabry disease mutation, p.Arg227Ter or p.R227*, in Finland.

Results

Four males and ten females belonged to two extended families. The mean age was 46 years (SD 18.4). Six patients (43%) had cardiac hypertrophy, three patients (21%) had ischemic stroke, and none had severe kidney dysfunction. Three patients had atrial fibrillation; two patients who had atrial fibrillation also had pacemakers. All males over 30 years of age had at least one of the following manifestations: cardiac hypertrophy, stroke, or proteinuria. In females, the severity of Fabry disease varied from classic multiorgan disease to a condition that mimicked the attenuated cardiac variant. No one was totally asymptomatic without any signs of Fabry disease. Cardiac magnetic resonance imaging was performed on nine of 14 patients was the most sensitive for detecting early cardiac manifestations. Five patients (55%) had late gadolinium enhancement‐positive segments.

Conclusion

Cardiac involvement should be effectively detected in females before considering them asymptomatic mutation carriers.

MALDI imaging in Fabry nephropathy: a multicenter study

BACKGROUND

The current study evaluates the application of histology and in situ proteomics (MALDI-MSI) in Fabry nephropathy (FN), showing investigative and classification role for this coupled approach.

METHODS

A retrospective series of 14 formalin fixed paraffin embedded (FFPE) renal biopsies with diagnosis of FN and 1 biopsy from a patient bearing a galactosidase-α (GLA) genetic variant of unknown significance (GVUS, c.376A>G) have been classified for clinical characteristics. Groups were compared for histological differences (following the ISGFN scoring system). Moreover, renal biopsies from these cases have been analyzed with MALDI-MSI as previously described to find proteomic signatures among different mutations and phenotypes.

RESULTS

Comparison of clinical features revealed lower mean 24 h proteinuria in females (225 mg/24 h) than in males (1477.5 mg/24 h, p = 0.006). As for clinical characteristics, females significantly differed from males only for lower arterial sclerosis, with a mean value of 0.82 vs. 1.05 (p = 0.001). Proteomic analysis demonstrated specific signatures in different subgroups of FN patients. Moreover, MALDI correctly classified cases with undetermined mutation or GVUS.

CONCLUSIONS

The present study demonstrated the feasible application of MALDI-MSI in the analysis of FN FFPE renal biopsies, allowing the detection of putative signatures for phenotypic distinction and demonstrating genetic classification capabilities.

The Mini Mental State Examination does not accurately screen for objective cognitive impairment in Fabry Disease

Fabry disease (FD) patients may suffer from objective cognitive impairment (OCI). This study assessed the accuracy of the Mini Mental State Examination (MMSE) to screen for OCI in FD patients. Presence or absence of OCI was established using a neuropsychological test battery. For different MMSE cutoffs sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and clinical utility index (CUI) to identify OCI were calculated. Eighty-one patients were included (mean age 44.5 ± 14.3, 35% men, 74% classical phenotype) of which 13 patients (16%) had OCI. The median MMSE score was 29 (range: 25-30). MMSE cutoffs ≤28 and ≤29 had the highest sensitivity and specificity, with higher specificity reached at cutoff ≤28 (sensitivity: .46, specificity: .73) and higher sensitivity at cutoff ≤29 (sensitivity: .92, specificity: .40). PPV was low for both cutoffs (PPV ≤28: .25, PPV ≤29: .23) resulting in a low positive CUI (case finding ability). The results of our study indicate that the MMSE does not accurately screen for OCI in FD, with poor sensitivity-specificity trade-off at all cutoffs. The low PPV shows that the majority of FD patients that score below the cutoffs do not suffer from OCI. Administering the MMSE as a screening test will lead to unnecessary referrals for neuropsychological testing, which is time consuming and burdensome. Screening tools designed to accurately detect mild (executive) impairment might prove more appropriate to screen for OCI in FD.

Low-dose agalsidase beta treatment in male pediatric patients with Fabry disease: A 5-year randomized controlled trial

BACKGROUND

Fabry disease is a rare, X-linked, lifelong progressive lysosomal storage disorder. Severely deficient α-galactosidase A activity in males is associated with the classic phenotype with early-onset, multisystem manifestations evolving to vital organ complications during adulthood. We assessed the ability of 2 low-dose agalsidase beta regimens to lower skin, plasma, and urine globotriaosylceramide (GL-3) levels, and influence clinical manifestations in male pediatric Fabry patients.

METHODS

In this multicenter, open-label, parallel-group, phase 3b study, male patients aged 5-18 years were randomized to receive agalsidase beta at 0.5 mg/kg 2-weekly (n = 16) or 1.0 mg/kg 4-weekly (n = 15) for 5 years. All had plasma/urine GL-3 accumulation but no clinically evident organ involvement. The primary outcome was GL-3 accumulation in superficial skin capillary endothelium (SSCE).

RESULTS

The mean age was 11.6 (range: 5-18) years and all but one of the 31 patients had classic GLA mutations. In the overall cohort, shifts from non-0 to 0-scores for SSCE GL-3 were significant at years 1, 3, and 5, but results were variable. Plasma GL-3 normalized and urine GL-3 reduced substantially. Higher anti-agalsidase beta antibody titers were associated with less robust SSCE GL-3 clearance and higher urine GL-3 levels. Renal function remained stable and normal. Most Fabry signs and symptoms tended to stabilize; abdominal pain was significantly reduced (-26.3%; P = .0215). No new clinical major organ complications were observed. GL-3 accumulation and cellular and vascular injury were present in baseline kidney biopsies (n = 7). Treatment effects on podocyte GL-3 content and foot process width were highly variable. Fabry arteriopathy overall increased in severity. Two patients withdrew and 2 had their agalsidase beta dose increased.

CONCLUSIONS

Our findings increase the limited amount of available data on long-term effects of enzyme replacement therapy in pediatric, classic Fabry patients. The low-dose regimens studied here over a period of 5 years did not demonstrate a consistent benefit among the patients in terms of controlling symptomatology, urine GL-3 levels, and pathological histology. The current available evidence supports treatment of pediatric, classic male Fabry patients at the approved agalsidase beta dose of 1.0 mg/kg 2-weekly if these patients are considered for enzyme replacement therapy with agalsidase beta.

Tandem mass spectrometry analysis of urinary podocalyxin and podocin in the investigation of podocyturia in women with preeclampsia and Fabry disease patients

BACKGROUND

Podocytes are highly differentiated visceral cells, and several related specific proteins, such as podocalyxin and podocin are potential tools for the evaluation of podocyturia. However, precise quantitation of podocyturia-related proteins is complex and often unreliable.

METHOD

A reversed-phase ultra-performance liquid chromatography coupled to tandem mass spectrometry method was developed and validated to quantify podocalyxin and podocin levels in urine supernatant by using specific cleavable peptides and standards. Urine samples from women with normotensive or hypertensive pregnancies, gestational diabetes and preeclampsia, as well as treated and untreated Fabry patients, and gender-matched controls were investigated.

RESULTS

The multiplex analysis shows that podocalyxin levels were higher than podocin levels in patients, the former being particularly higher in pregnant women. Women with preeclampsia had abnormal urine levels of both proteins with a higher sensitivity for podocalyxin. Slightly increased levels of podocin were also observed in Fabry males, while both proteins were increased in untreated Fabry females. Correlations were established between podocalyxin and podocin levels and clinical parameters associated with Fabry disease and preeclampsia.

CONCLUSIONS

This methodology makes possible the precise, simultaneous and reliable analysis of podocalyxin and podocin levels, and offers a valuable tool for the evaluation of podocyturia.

Multiple phenotypic domains of Fabry disease and their relevance for establishing genotype- phenotype correlations

Fabry disease (FD) is a rare X-linked glycosphingolipidosis resulting from deficient α-galactosidase A (AGAL) activity, caused by pathogenic mutations in the GLA gene. In males, the multisystemic involvement and the severity of tissue injury are critically dependent on the level of AGAL residual enzyme activity (REA) and on the metabolic load of the disease, but organ susceptibility to damage varies widely, with heart appearing as the most vulnerable to storage pathology, even with relatively high REA. The expression of FD can be conceived as a multidomain phenotype, where each of the component domains is the laboratory or clinical expression of the causative GLA mutation along a complex pathophysiologic cascade pathway. The AGAL enzyme activity is the most clinically useful marker of the protein phenotype. The metabolic phenotype and the pathologic phenotype are diverse expressions of the storage pathology, respectively, assessed by biochemical and histological/ultrastructural methods. The storage phenotypes are the direct consequences of enzyme deficiency and hence, together with the enzymatic phenotype, constitute the more specific diagnostic markers of FD. In the pathophysiology cascade, the clinical phenotypes are most distantly linked to the underlying genetic causation, being critically influenced by the patients’ gender and age, and modulated by the effects of variation in other genetic loci, of polygenic inheritance and of environmental risk factors. A major challenge in the clinical phenotyping of patients with FD is the differential diagnosis between its nonspecific, later-onset complications, particularly the cerebrovascular, cardiac and renal, and similar chronic illnesses that are common in the general population. Comprehensive phenotyping, whenever possible performed in hemizygous males, is therefore crucial for grading the severity of pathogenic GLA variants, to clarify the phenotypic correlations of hypomorphic alleles, to define benign polymorphisms, as well as to establish the pathogenicity of variants of uncertain significance.

Efficacy of the pharmacologic chaperone migalastat in a subset of male patients with the classic phenotype of Fabry disease and migalastat-amenable variants: data from the phase 3 randomized, multicenter, double-blind clinical trial and extension study

PURPOSE

Outcomes in patients with Fabry disease receiving migalastat during the phase 3 FACETS trial (NCT00925301) were evaluated by phenotype.

METHODS

Data were evaluated in two subgroups of patients with migalastat-amenable GLA variants: "classic phenotype" (n = 14; males with residual peripheral blood mononuclear cell α-galactosidase A <3% normal and multiorgan system involvement) and "other patients" (n = 36; males not meeting classic phenotype criteria and all females). Endpoints included estimated glomerular filtration rate (eGFR), left ventricular mass index (LVMi), Gastrointestinal Symptoms Rating Scale diarrhea subscale (GSRS-D), renal peritubular capillary (PTC) globotriaosylceramide (GL-3) inclusions, and plasma globotriaosylsphingosine (lyso-Gb₃).

RESULTS

Baseline measures in the classic phenotype patients suggested a more severe phenotype. At month 24, mean (SD) annualized change in eGFR_CKD-EPI with migalastat was -0.3 (3.76) mL/min/1.73 m² in the classic phenotype subgroup; changes in LVMi, GSRS-D, and lyso-Gb₃ were -16.7 (18.64) g/m², -0.9 (1.66), and -36.8 (35.78) nmol/L, respectively. At month 6, mean PTC GL-3 inclusions decreased with migalastat (-0.8) and increased with placebo (0.3); switching from placebo to migalastat, PTC inclusions decreased by -0.7. Numerically smaller changes in these endpoints were observed in the other patients.

CONCLUSION

Migalastat provided clinical benefit to patients with Fabry disease and amenable variants, regardless of disease severity.