Neurological complications in Fabry disease

Background. Prior to the introduction of enzyme replacement therapy (ERT), management of Fabry disease (FD) consisted of symptomatic and palliative measures. ERT has been available for several years using recombinant human agalsidase alfa, an analogue of alpha-galactosidase A (GALA). However, the limitations of ERT in improving kidney function have not been established. This study evaluates the safety and therapeutic effect of agalsidase alfa replacement in terms of kidney function and reduction in 24-hour proteinuria. Methods. During the period between January 1, 2002, and August 1, 2005, nine Fabry patients (7 male, 2 female) were treated according to protocol, receiving 0.2 mg/kg agalsidase alfa IV every two weeks. Kidney function was evaluated by measuring the glomerular filtration rate (GFR) using chromium ethylene diamine tetra-acetate clearance (51Cr-EDTA mL/min/ 1.73 m2) at baseline, 12, 24, and 36 months. 24-hour proteinuria was measured at baseline, 3, 6, 12, 18, 24, and 36 months of ERT. Kidney disease was classified according to National Kidney Foundation Disease Outcome Quality Initiative (NKF/DOQI) Advisory Board criteria, which define stage I chronic kidney disease (CKD) as GFR ≥ 90mL/min/1.73 m2, stage II as 60–89 mL/min/1.73m2, stage III as 30–59 mL/min/1.73 m2, stage IV as 15–29 mL/min/1.73m2, and stage V as < 15 mL/min/1.73m2. Results. Six patients completed 36 months of therapy, 2 patients completed 18 months, and 1 patient completed 12 months. Mean patient age at baseline was 34.6 ± 11.3 years. During the study period, kidney function remained stable in patients with stages I, II, or III CKD. One patient, who entered the study with stage IV CKD, progressed to end-stage chronic kidney disease, beginning hemodialysis after 7 months and receiving a kidney transplant after 12 months of ERT. Proteinuria also remained stable in the group of patients with pathologic proteinuria. The use of agalsidase alfa was well tolerated in 99.5% of the infusions administered. Conclusion. Over the course of 36 months of ERT, there was no change in kidney function and 24-hour proteinuria. This suggests that agalsidase alfa may slow or halt the progression of kidney disease when used before extensive kidney damage occurs. No significant side effects were observed with ERT during the course of the study.

Fabry disease (McKusick 301500) is an X-linked lysosomal storage disorder secondary to deficient alpha-galactosidase A activity which leads to the widespread accumulation of globotriaosylceramide (Gb(3)) and related glycosphingolipids, especially in vascular smooth-muscle and endothelial cells. We have recently shown that the myocardial perfusion reserve of Fabry patients is significantly decreased. Thus, in the present study we investigated, whether it can be improved with enzyme replacement therapy (ERT). Ten patients (7 male, 3 female; mean age 34, range 19-49 years) with confirmed Fabry disease were approved for this uncontrolled, open-label study. Myocardial perfusion was measured at rest and during dipyridamole-induced hyperaemia by positron emission tomography and radiowater. Myocardial perfusion reserve was calculated as the ratio between maximal and resting perfusion. Perfusion measurements were performed before and after 6 and 12 months of ERT by recombinant human alpha-galactosidase A (Fabrazyme, Genzyme). Plasma Gb(3) concentration decreased significantly and the patients reported that they felt better and suffered less pain after the ERT. However, neither resting or dipyridamole-stimulated myocardial perfusion nor myocardial perfusion reserve changed during the ERT. Pretreatment relative wall thickness correlated negatively with posttreatment changes in flow reserve (r = -0.76, p = 0.05) and positively with posttreatment changes in minimal coronary resistance (r = 0.80, p = 0.03). This study shows that 12 months of ERT does not improve myocardial perfusion reserve, although the plasma Gb(3) concentration decreases. However, individual variation in the response to therapy was large and the results suggest that the success of the therapy may depend on the degree of cardiac hypertrophy.

Fabry disease is a rare X-linked disease characterized by deficient expression and activity of alpha-galactosidase A with consequent lysosomal accumulation of glycosphingolipids, particularly globotriaosylceramide in various organs. Currently, enzyme replacement therapy with recombinant human α-galactosidase is the cornerstone of the treatment of Fabry patients, although in the long term enzyme replacement therapy fails to halt disease progression, in particular in case of late diagnosis. This suggests that the adverse outcomes cannot be justified by the lysosomal accumulation of glycosphingolipids alone, and that additional therapies targeted at further pathophysiologic mechanisms might contribute to halting the progression of cardiac, cerebrovascular and kidney disease in Fabry patients. Recent evidence points toward the involvement of oxidative stress, oxidative stress signaling and inflammation in the pathophysiology of cardio cerebrovascular and kidney damage in Fabry patients. This review reports the current knowledge of the involvement of oxidative stress in Fabry disease, which clearly points toward the involvement of oxidative stress in the pathophysiology of the medium to long-term cardio-cerebrovascular-kidney damage of Fabry patients and summarizes the antioxidant therapeutic approaches currently available in the literature. This important role played by oxidative stress suggests potential novel additional therapeutic interventions by either pharmacologic or nutritional measures, on top of enzyme replacement therapy, aimed at improving/halting the progression of cardio-cerebrovascular disease and nephropathy that occur in Fabry patients.

The human lysosomal enzymes alpha-galactosidase (alpha-GAL, EC 3.2.1.22) and alpha-N-acetylgalactosaminidase (alpha-NAGAL, EC 3.2.1.49) share 46% amino acid sequence identity and have similar folds. The active sites of the two enzymes share 11 of 13 amino acids, differing only where they interact with the 2-position of the substrates. Using a rational protein engineering approach, we interconverted the enzymatic specificity of alpha- GAL and alpha-NAGAL. The engineered alpha-GAL (which we call alpha-GAL(SA)) retains the antigenicity of alpha-GAL but has acquired the enzymatic specificity of alpha-NAGAL. Conversely, the engineered alpha-NAGAL (which we call alpha-NAGAL(EL)) retains the antigenicity of alpha-NAGAL but has acquired the enzymatic specificity of the alpha-GAL enzyme. Comparison of the crystal structures of the designed enzyme alpha-GAL(SA) to the wild-type enzymes shows that active sites of alpha-GAL(SA) and alpha-NAGAL superimpose well, indicating success of the rational design. The designed enzymes might be useful as non-immunogenic alternatives in enzyme replacement therapy for treatment of lysosomal storage disorders such as Fabry disease.

BackgroundFabry disease is caused by a deficiency of the lysosomal enzyme α-galactosidase, resulting in progressive accumulation of globotriaosylceramide (GL-3). The disease can manifest early during childhood and adolescence. Enzyme replacement therapy (ERT) with recombinant human α-galactosidase is the first specific treatment for Fabry disease and has been available in Europe since 2001. This paper presents the findings of a systematic literature review of clinical outcomes with ERT in paediatric patients with Fabry disease. MethodsA comprehensive systematic review of published literature on ERT in Fabry disease was conducted in January 2017. The literature analysis included all original articles reporting outcomes of ERT in paediatric patients. ResultsTreatment-related outcomes in the paediatric population were reported in six publications derived from open-label clinical trials and in 10 publications derived from observational or registry-based studies. ERT was shown to significantly reduce plasma and urine GL-3 levels in paediatric patients with Fabry disease. The effect of ERT on GL-3 clearance from renal podocytes appeared to be agalsidase dose-dependent. ERT relieved pain and improved gastrointestinal symptoms and quality of life. ConclusionsBased on the published literature, the use of ERT in paediatric patients can significantly clear GL-3 accumulation, ameliorate the early symptoms of Fabry disease, and improve quality of life. Treatment with ERT in paediatric patients with Fabry disease may be important to prevent further disease progression and overt organ damage.

Objective: To measure coronary flow reserve (CFR), an index of microvascular function, in Anderson-Fabry disease (AFD) at baseline and after enzyme replacement therapy (ERT). Methods and results: Mean (SD) myocardial...

Anderson-Fabry disease (referred to as Fabry disease) is an X-linked disorder characterized by a deficiency of the lysosomal enzyme alpha-galactosidase A and the subsequent accumulation in various tissues of globotriaosylceramide (Gb(3)), the main substrate of the defective enzyme. Enzyme replacement therapy (ERT) offers a specific treatment for patients with Fabry disease, though monitoring of treatment is hampered by a lack of surrogate markers of response. In this study, the efficacy of long-term ERT in six Fabry hemizygotes and two symptomatic heterozygotes has been evaluated. Patients were administered recombinant alpha-galactosidase A every 2 weeks for up to a year. The efficacy of ERT was assessed by monitoring symptomatology and renal function. Urinary glycolipid concentration was estimated by a novel tandem mass spectrometric method. Urine glycolipid (Gb(3)) was elevated at baseline and fell impressively on ERT where patients were hemizygotes and in the absence of renal transplantation. In heterozygotes and in a recipient of a renal allograft, elevations and changes in urine glycolipids were less pronounced. In one patient, after several months of ERT, there was a transient increase in Gb(3) concentrations to baseline (pre-ERT) levels, associated with the presence of antibodies to the recombinant alpha-galactosidase A. The marked decline in urine Gb(3) on ERT, and its subsequent increase in association with an inhibitory antibody response, suggest that this analyte deserves further investigation as a potential marker of disease severity and response to treatment.

Optimizing treatment to reach therapeutic goals in fabry disease

In this issue, Banikazemi and colleagues' landmark trial on Fabry disease provides a crucial path toward lowering the morbidity of this disease. Among other findings, they determined that hemizygou...

Enzyme replacement therapy (ERT) has been shown to enhance microvascular endothelial globotriaosylceramide clearance in the hearts of patients with Fabry disease. Whether these results can be translated into an improvement of myocardial function has yet to be demonstrated. Sixteen patients with Fabry disease who were treated in an open-label study with 1.0 mg/kg body weight of recombinant alpha-Gal A (agalsidase beta, Fabrazyme) were followed up for 12 months. Myocardial function was quantified by ultrasonic strain rate imaging to assess radial and longitudinal myocardial deformation. End-diastolic thickness of the left ventricular posterior wall and myocardial mass (assessed by magnetic resonance imaging, n=10) was measured at baseline and after 12 months of ERT. Data were compared with 16 age-matched healthy controls. At baseline, both peak systolic strain rate and systolic strain were significantly reduced in the radial and longitudinal direction in patients compared with controls. Peak systolic strain rate increased significantly in the posterior wall (radial function) after one year of treatment (baseline, 2.8+/-0.2 s(-1); 12 months, 3.7+/-0.3 s(-1); P<0.05). In addition, end-systolic strain of the posterior wall increased significantly (baseline, 34+/-3%; 12 months, 45+/-4%; P<0.05). This enhancement in radial function was accompanied by an improvement in longitudinal function. End-diastolic thickness of the posterior wall decreased significantly after 12 months of treatment (baseline, 13.8+/-0.6 mm; 12 months, 11.8+/-0.6 mm; P<0.05). In parallel, myocardial mass decreased significantly from 201+/-18 to 180+/-21 g (P<0.05). These results suggest that ERT can decrease left ventricular hypertrophy and improve regional myocardial function.

Fabry disease has diverse neurological manifestations, many of which influence morbidity and quality of life. The aim of the study was to document the clinical and subclinical neurological manifestations in a cohort of Australian patients with Fabry disease, using multiple clinical tools and a multidisciplinary approach. Participants completed focused questionnaires and underwent clinical neurological examination, Neurocognitive testing using Mini Mental State Examination and Neuropsychiatry Unit Cognitive Screen, Quantitative Sensory Testing (QST), autonomic assessment using RR interval variation, intracranial magnetic resonance imaging (MRI) and audiology. In subsets of patients who had previously undergone QST and/or prospective serial quality-of-life assessments over the previous 5 years, results before and after enzyme replacement therapy were compared. Twenty hemizygotes and two heterozygotes were recruited. The age (mean +/- standard deviation (SD)) of male participants was 40.4 +/- 11.9 years (range 20-62 years); the women were aged between 20 and 56 years. Increasing age was strongly associated with increasing neurological disability. Clinical peripheral neuropathy predominantly affected thermal sensation in all patients, with variable involvement of pinprick and light touch. QST confirmed these findings. Clinical cerebellar tests were commonly abnormal: this has not been previously reported in the absence of symptomatic cerebrovascular disease. There was hearing loss was in 90% of patients and no patient older than 44 years had normal hearing. MRI lesion prevalence increased with age. Despite neurological complications being common, formal cognitive testing was basically normal. QST thresholds for pain showed a significant change after enzyme replacement therapy. Neurological complications in Fabry disease are common, complex and may be devastating. All patients studied had neurological involvement, with protean and diverse manifestations.

Enzyme replacement therapy for Fabry disease: Morphologic and histochemical changes in the urinary sediments

Background Fabry cardiomyopathy is associated with an increased risk for major cardiovascular events (MACE) and premature mortality. While enzyme replacement therapy (ERT) remains the cornerstone of treatment, pragmatic tools to monitor treatment response are lacking. Purpose We aim to investigate the association between the response of left ventricular (LV) global longitudinal strain (GLS) after starting ERT and its impact on MACE in patients with Fabry disease. Methods We conducted a retrospective cohort study using a single-center registry of adult patients with Fabry disease. LV GLS was measured by speckle-tracking echocardiography and reported as absolute values. The change in LV GLS was calculated as the percent change of GLS between baseline and one year after ERT. The primary outcome was a composite of MACE at five years, including all-cause mortality, heart failure hospitalization, sustained ventricular tachycardia, acute ischemic stroke, and permanent pacemaker implantation. Results This study included 162 patients with Fabry disease (age 53.4 ± 14.5 years, 52.5% men), 86.4% of whom carried the IVS4+919G&amp;gt;A mutation. Among them, 88 patients received ERT. After one year, patients receiving ERT exhibited a trend of slower decline in LV GLS compared to those not receiving ERT (-1.8% vs. -15.1%; P= 0.08) (Figure 1). Over a median follow-up of 60 months, nine patients (10.2%) experienced MACE. Kaplan-Meier analysis showed that patients on ERT with an LV GLS decline of less than 10% had a significantly lower risk for MACE compared to those with a greater decline in LV GLS (log-rank P= 0.001) (Figure 2). In multivariable Cox regression analysis, a reduction in LV GLS of more than 10% was independently associated with an increased risk of MACE over five years (adjusted hazard ratio: 8.66, 95% confidence interval: 1.53-49.18; P= 0.01) after adjusting for age, sex, LV ejection fraction, LV filling pressure, baseline LV mass index, and baseline LV GLS. Conclusion Patients with Fabry disease exhibit diverse clinical presentations and face varying risks for MACE despite treatment. Our study highlights the response of LV mechanical function as a practical tool for monitoring the efficacy of ERT and identifying high-risk patients who may benefit from intensive management.Figure 1.Trend of LV GLS in subgroups Figure 2.Kaplan-Meier curves

A Case Report of Kidney After Heart Transplant in Patient With Fabry Disease

Fabry Disease (FD) is an X-linked lysosomal storage disorder (prevalence about 1 : 100 000) caused by a genetic defect associated with a lack of alpha-galactosidase A (alpha-GAL) enzyme activity. As a consequence, neutral glycosphingolipides can not be cleaved and metabolized, and accumulate in lysosomes of several tissues, particularly in vascular endothelium and smooth muscle cells. The most prominent symptoms comprise pain attacks and acroparesthesia, angiokeratoma, corneal opacity, renal and cardiac dysfunction, hypo- and anhidrosis, gastrointestinal symptoms, and cerebrovascular dysfunction with vertigo, headache, and cerebral ischemia. Characteristic symptoms of FD can occur in male and female patients with the same prevalence, while females with FD seem to be less severely affected. The course of untreated illness is progressive with considerable interindividual variability. Since 2001 two enzyme replacement therapies are approved which can possibly stop the disease progress and alleviate symptoms. The very few reports and clinical observations have shown that a very high proportion of FD patients develop neuropsychiatric symptoms. However, accurate data are lacking. Although the pathophysiologic mechanisms are quite unknown, it is surmised that sphingolipid deposits in the endothelium of small cerebral vessels lead to regional cerebral ischemia accompanied by neuropsychiatric symptoms and deficits. Furthermore, patients with FD are chronically distressed by pain attacks and additional somatic and psychological impairment. Frequently, pain attacks are triggered by psychosocial stress. The high interindividual variability can, thus, also be interpreted on the basis of existing stress and coping models. The present paper will review the presently available psychiatric and neuropsychological findings in FD and will discuss difficulties associated with classification and differential diagnosis of psychiatric disorders occurring in patients with FD.