Cardiac manifestations of Anderson-Fabry disease in children and adolescents

Ventricular arrhythmias and primary prevention of sudden cardiac death in Anderson-Fabry disease

The Anderson-Fabry disease (AFD) is a X-linked lysosomal storage disorder due to the deficiency in the α-galactosidase A enzyme. Cardiovascular mortality is a major cause of death in patients with AFD and sudden cardiac death (SCD) is one of the main causes of death. The storage of glycosphingolipid along with ionic channel impairment, inflammation and fibrosis are involved in the arrhythmogenesis. Some risk factors have been associated with ventricular tachycardia (VT)/ventricular fibrillation (VF) and SCD. Left ventricular hypertrophy (LVH), cardiac fibrosis, non-sustained VTs seem to be the most important. Older age and male gender might be associated with higher risk of ventricular arrhythmias and SCD. Currently, the implantable cardioverter-defibrillator (ICD) is recommended in patients with AFD who have survived a cardiac arrest secondary to VT/VF or who experienced sustained VT causing syncope or hemodynamic compromise, and have a life expectancy >1 year. ICD implantation is also recommended in patients considered to be at high risk (e.g., patients with severe LVH or fibrosis). The present review sought to summarize the risk of ventricular arrythmias in AFD, the indications for ICD, focusing on pathophysiology and analyzing the role of possible predictors of arrhythmias in preventing SCD, especially as primary prevention.

Unique Aspects of Hypertrophic Cardiomyopathy in Children

Hypertrophic cardiomyopathy (HCM) is a primary heart muscle disease characterized by left ventricular hypertrophy that can be asymptomatic or with presentations that vary from left ventricular outflow tract obstruction, heart failure from diastolic dysfunction, arrhythmias, and/or sudden cardiac death. Children younger than 1 year of age tend to have worse outcomes and often have HCM secondary to inborn errors of metabolism or syndromes such as RASopathies. For children who survive or are diagnosed after 1 year of age, HCM outcomes are often favourable and similar to those seen in adults. This is because of sudden cardiac death risk stratification and medical and surgical innovations. Genetic testing and timely cardiac screening are paving the way for disease-modifying treatment as gene-specific therapies are being developed.

Anderson-Fabry Disease: Red Flags for Early Diagnosis of Cardiac Involvement

Anderson-Fabry disease (AFD) is a lysosome storage disorder resulting from an X-linked inheritance of a mutation in the galactosidase A (GLA) gene encoding for the enzyme alpha-galactosidase A (α-GAL A). This mutation results in a deficiency or absence of α-GAL A activity, with a progressive intracellular deposition of glycosphingolipids leading to organ dysfunction and failure. Cardiac damage starts early in life, often occurring sub-clinically before overt cardiac symptoms. Left ventricular hypertrophy represents a common cardiac manifestation, albeit conduction system impairment, arrhythmias, and valvular abnormalities may also characterize AFD. Even in consideration of pleiotropic manifestation, diagnosis is often challenging. Thus, knowledge of cardiac and extracardiac diagnostic "red flags" is needed to guide a timely diagnosis. Indeed, considering its systemic involvement, a multidisciplinary approach may be helpful in discerning AFD-related cardiac disease. Beyond clinical pearls, a practical approach to assist clinicians in diagnosing AFD includes optimal management of biochemical tests, genetic tests, and cardiac biopsy. We extensively reviewed the current literature on AFD cardiomyopathy, focusing on cardiac "red flags" that may represent key diagnostic tools to establish a timely diagnosis. Furthermore, clinical findings to identify patients at higher risk of sudden death are also highlighted.

Impact of enzyme replacement therapy and migalastat on left atrial strain and cardiomyopathy in patients with Fabry disease

Aims

Cardiomyopathy in Fabry disease (FD) is a major determinant of morbidity and mortality. This study investigates the effects of FD-specific treatment using enzyme replacement therapy (ERT) and chaperone therapy on left atrial (LA) function using two-dimensional speckle tracking echocardiography (2DSTE).

Methods and results

In this prospective observational single-center study, 20 FD patients [10 (50%) females] treated with migalastat, 48 FD patients [24 (50%) females] treated with ERT (agalsidase-alfa and agalsidase-beta), and 30 untreated FD patients (all females) as controls were analyzed. The mean follow-up time ranged from 26 to 81 months. 2DSTE was performed for left ventricle strain, right ventricle strain, and LA strain (LAS). FD-specific treated patients presented with increased left ventricular mass index (LVMi) and higher frequency of left ventricular hypertrophy at baseline, whereas untreated control patients showed normal baseline values. FD-specific treated (including migalastat and ERT) patients showed stabilization of LAS over time (p > 0.05). LVMi was also stable in treated FD patients during observation (p > 0.05).

Conclusion

In patients with FD, treated with either ERT or chaperone therapy, LAS values measured by echocardiographic speckle tracking were stable over time, pointing toward disease stabilization.

Treatment of Fabry Disease: Established and Emerging Therapies

Fabry disease (FD) is a rare, X-linked inherited disorder of glycosphingolipid metabolism. It leads to the progressive accumulation of globotriaosylceramide within lysosomes due to a deficiency of α-galactosidase A enzyme. It involves multiple organs, predominantly the renal, cardiac, and cerebrovascular systems. Early diagnosis and treatment are critical to prevent progression to irreversible tissue damage and organ failure, and to halt life-threatening complications that can significantly reduce life expectancy. This review will focus on the established and emerging treatment options for FD.

Palm-Plant Pain, Sign of a Severe Systemic Disease? Case Report and Review of Literature

Fabry disease is an X-linked lysosomal storage disease, second in prevalence after Gaucher disease. The onset of symptoms occurs in childhood or adolescence with palmo-plantar burning pains, hypo hidrosis, angiokeratomas, and corneal deposits. In the absence of diagnosis and treatment, the disease will progress to the late phase, characterized by progressive cardiac, cerebral and renal damage, and possible death. We present the case of an 11-year-old male boy who was transferred to the Pediatric Nephrology Department for palmo-plantar burning pain and end stage renal disease. Following the evaluations for the etiology of end stage renal disease we excluded the vasculitis, the neurologic diseases, extrapulmonary tuberculosis. Because of suggestive aspect at CT scan and lack of etiologic diagnosis of renal insufficiency we performed lymph node and kidney biopsy, with a surprising result for storage disease. The specific investigation confirmed the diagnosis.

Cardiac MRI in Fabry disease

Fabry disease is a rare, progressive X-linked inherited disorder of glycosphingolipid metabolism due to a deficiency of α-galactosidase A enzyme. It leads to the accumulation of globotriaosylceramide within lysosomes of multiple organs, predominantly the vascular, renal, cardiac, and nervous systems. Fabry cardiomyopathy is characterized by increased left ventricular wall thickness/mass, functional abnormalities, valvular heart disease, arrhythmias, and heart failure. Early diagnosis and treatment are critical to avoid cardiac or renal complications that can significantly reduce life expectancy in untreated FD. This review will focus on the role of cardiovascular magnetic resonance imaging in the diagnosis, clinical decision-making, and monitoring of treatment efficacy.

Clinical outcomes among young patients with Fabry disease who initiated agalsidase beta treatment before 30 years of age: An analysis from the Fabry Registry

BACKGROUND

Clinical manifestations of classic Fabry disease (α-galactosidase A deficiency) usually occur in childhood, while complications involving major organs typically develop in adulthood. Outcomes of Fabry-specific treatment among young patients have not been extensively reported. Our aim was to analyze clinical outcomes among patients aged 5-30 years at initiation of treatment with agalsidase beta using data from the Fabry Registry (NCT00196742, sponsor: Sanofi).

METHODS

Reported GLA variants were predicted to be associated with the classic phenotype or not classified in fabry-database.org. Linear mixed models were conducted to assess changes over ≥2-year follow-up in the estimated glomerular filtration rate (eGFR) stratified by low (LRI) and high (HRI) renal involvement (defined by proteinuria/albuminuria levels), and changes in interventricular septal thickness (IVST) and left ventricular posterior wall thickness (LVPWT) Z-scores stratified by median age at first treatment. Self-reports ('yes'/'no') of abdominal pain, diarrhea, chronic peripheral pain (denoting neuropathic pain), and acute pain crises at baseline were compared with reports after ≥0.5-year and ≥2.5-year follow-up using McNemar's test.

RESULTS

Male (n = 117) and female patients (n = 59) with LRI initiated treatment at a median age of 19.9 and 23.6 years, respectively, and were followed for a median of 6.3 and 5.0 years, respectively. The eGFR slopes were -1.18 (P_{from 0} <0.001) and -0.92 mL/min/1.73 m²/year (P_{from 0} = 0.040), respectively. Males with HRI (n = 23, median UPCR 1.0 g/g), who started treatment at a median age of 26.7 years, had an eGFR slope of -2.39 mL/min/1.73 m²/year (P_{from 0} <0.001; P_difference = 0.055, as compared with the slope of -1.18 mL/min/1.73 m²/year for LRI males) during a median follow-up of 5.6 years. Echocardiographic variables were stable among males, regardless of age, and among young females (median follow-up >5.5 years and ≥4.5 years, respectively). Older females (treatment initiation at median age 27.5 years) had a slope of LVPWT Z-scores of 0.18/year (n = 12, P_{from 0} = 0.028), whereas IVST Z-scores remained stable (n = 13, 0.10/year, P_{from 0} = 0.304) during a median follow-up of ≥3.7 years. These slopes did not significantly differ from slopes of younger females. Reports of chronic peripheral pain and acute pain crises by males, and of diarrhea and acute pain crises by females, significantly reduced after a median follow-up of ≥4.0 years. After a median follow-up of ≥5.4 years, reports of all four symptoms significantly decreased among males, whereas among females only reports of abdominal pain significantly decreased.

CONCLUSIONS

During sustained treatment with agalsidase beta in young Fabry patients with a predicted classic phenotype or with unclassified GLA variants with similar characteristics, the decline in eGFR was modest among male and female patients with LRI. The greater decline in eGFR among older, proteinuric (i.e., HRI) males may suggest a benefit of earlier treatment. Overall, echocardiographic variables remained stable, particularly among males and younger females. Significant reductions in symptom reports occurred primarily among males after longer follow-up and were less noticeable among females. These observed trends are suggestive of an overall improvement after treatment in young patients, but warrant larger longitudinal studies.

Clinical features and enzyme replacement therapy in 10 children with Fabry disease

OBJECTIVE

To summarize the clinical features, diagnosis and enzyme replacement therapy(ERT) of Fabry disease (FD) in children.

METHODS

The clinical data, laboratory tests, genetic variations and treatment of 10 FD children diagnosed in Shandong Provincial Hospital from September 2020 to June 2022 were retrospectively analyzed.

RESULTS

Among the 10 cases from 6 families, 7 patients were boys of 4 to 13 years of age, and 3 were girls of 12 to 15 years of age. There were 7 symptomatic patients, including 6 boys and 1 girl. All 7 patients presented with acral neuralgia. Five patients had little or no sweating. Five patients presented with cutaneous angiokeratoma. Two patients had abdominal pain. One patient developed joint symptoms. Four patients had corneal opacity. One patient had hearing loss; one patient had short stature. One patient had mild proteinuria and 1 patient had dysplasia of the right kidney with decreased eGFR (55.28 ml/min.1.73 m²). The left ventricular mass index was slightly elevated in 1 patient. Three patients had mild obstructive ventilatory dysfunction; a small amount of effusion in the intestinal space of the lower abdomen or mild fatty liver was found in 2 patients. Partial empty sella turcica in 1 patient. A total of 6 GLA gene variants were detected in 10 children, among which C.1059_1061delGAT (p.met353del) was a newly discovered mutation. Five children received ERT, of which 4 were treated with agalsidase beta and 1 was treated with agalsidase alpha. Only 1 patient had anaphylaxis. Lyso-GL-3 levels decreased significantly in the first 3 months of ERT initiation and remained relatively stable thereafter in 3 patients. The Lyso-GL-3 level was decreased, but renal impairment continued to progress in 1 patient treated with agalsidase alpha.

CONCLUSION

The clinical manifestations of FD in childhood are diverse, and it is necessary to make a definite diagnosis by combining family history, enzyme activity, biomarkers, gene testing and other indicators. Pedigree screening and high-risk population screening are helpful for early identification, early diagnosis and early treatment. No serious adverse reactions were found during the short-term treatment with agalsidase alpha and beta.

Fabry Disease, a Rare Disorder with Cardiac Manifestations. The Problem of Diagnosis and Treatment: a Literature Review

Fabry disease (FD) is an X-linked lysosomal storage disease caused by a mutation in the gene encoding α-galactosidase A and leads to reduced activity or complete absence of this enzyme, which causes the accumulation of globotriaosylceramide (Gb3) and its deacylated form (lyso-Gb3) in cells of the whole body. FD can occur both with multisystem manifestations, including damage to the nervous system, kidneys, and skin, and can affect only the heart. Cardiac involvement is a major cause of poor quality of life and death in patients with FD and an underrecognized cause of heart failure with preserved ejection fraction and ventricular arrhythmias in men over 30 years of age and women over 40 years of age. Cardiac damage begins at an early age, progresses subclinically until the appearance of significant symptoms, and usually manifests as leftventricular hypertrophy, mimicking hypertrophic cardiomyopathy. After the introduction of enzyme replacement therapy, early recognition of FD and differential diagnosis with other causes of leftventricular hypertrophy have become crucial to limit the progression of the disease. Recent advances in the understanding of cardiac pathophysiology and imaging have improved diagnostic and therapeutic approaches to the cardiac manifestations of this pathology. Modern achievements in the study of cardiac manifestations of FD have made it possible to significantly improve diagnostic and therapeutic approaches, in particular, in relation to the identification of pathogenetic mechanisms of organ damage and early disruption of their function. A better understanding of secondary pathogenic pathways, such as myocardial inflammation, may influence future therapeutic strategies and timely diagnosis of FD. Delay in diagnosis and untimely initiation of treatment remain critical problems for many patients with FD, especially for patients with late-onset cardiovascular manifestations, in whom treatment effects may be more limited and ineffective. Cooperation between specialists in genetic diseases and cardiologists remains important to identify patients before the appearance of cardiac symptoms in order to obtain maximum therapeutic effects.

Expert opinion on the recognition, diagnosis and management of children and adults with Fabry disease: a multidisciplinary Turkey perspective

This consensus statement by a panel of Fabry experts aimed to identify areas of consensus on conceptual, clinical and therapeutic aspects of Fabry disease (FD) and to provide guidance to healthcare providers on best practice in the management of pediatric and adult patients with FD. This consensus statement indicated the clinical heterogeneity of FD as well as a large number of pathogenic variants in the GLA gene, emphasizing a need for an individualized approach to patient care. The experts reached consensus on the critical role of a high index of suspicion in symptomatic patients and screening of certain at-risk groups to reveal timely and accurate diagnosis of FD along with an increased awareness of the treating physician about the different kinds of pathogenic variants and their clinical implications. The experts emphasized the crucial role of timely recognition of FD with minimal delay from symptom onset to definite diagnosis in better management of FD patients, given the likelihood of changing the disease's natural history, improving the patients' quality of life and the prognosis after enzyme replacement therapy (ERT) administered through a coordinated, multidisciplinary care approach. In this regard, this consensus document is expected to increase awareness among physicians about unique characteristics of FD to assist clinicians in recognizing FD with a well-established clinical suspicion consistent with pathogenic variants and gender-based heterogeneous clinical manifestations of FD and in translating this information into their clinical practice for best practice in the management of patients with FD.

Fabry Disease and the Heart: A Comprehensive Review

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

Altered pupillary light responses are associated with the severity of autonomic symptoms in patients with Fabry disease

Symptoms of autonomic dysfunction are common in Fabry disease. In this study we aimed to evaluate alterations in the pupillary response to white light stimulation in patients with Fabry disease and their association with the severity of autonomic symptoms. Fourteen consecutive patients with Fabry disease and 14 healthy control participants were enrolled in this cross-sectional study. The Mainz Severity Score Index (MSSI) was used to measure the severity of Fabry disease and the Composite Autonomic Symptom Scale 31 (COMPASS 31) questionnaire was used to evaluate the severity of autonomic symptoms. The pupil light responses were assessed with an infrared dynamic pupillometry unit. There were significant reductions in the amplitude (P = 0.048) and duration (P = 0.048) of pupil contraction, and the latency of pupil dilation (P = 0.048) in patients with Fabry disease compared to control subjects. The total weighted COMPASS 31 score correlated with MSSI (r = 0.592; P = 0.026) and the duration of pupil dilation (ρ = 0.561; P = 0.037). The pupillomotor weighted sub-score of the COMPASS 31 correlated inversely with the duration of pupil contraction (r = − 0.600; P = 0.023) and latency of pupil dilation (ρ = − 0.541; P = 0.046), and directly with the duration of pupil dilation (ρ = 0.877; P < 0.001) and MSSI (r = 0.533; P = 0.049). In conclusion, abnormal pupillary function is demonstrated in patients with Fabry disease, which is associated with the severity of autonomic symptoms.

An expert consensus document on the management of cardiovascular manifestations of Fabry disease

Fabry disease (FD) is an X-linked lysosomal storage disorder caused by pathogenic variants in the α-galactosidase A (GLA) gene that leads to reduced or undetectable α-galactosidase A enzyme activity and progressive accumulation of globotriaosylceramide and its deacylated form globotriaosylsphingosine in cells throughout the body. FD can be multisystemic with neurological, renal, cutaneous and cardiac involvement or be limited to the heart. Cardiac involvement is characterized by progressive cardiac hypertrophy, fibrosis, arrhythmias, heart failure and sudden cardiac death. The cardiac management of FD requires specific measures including enzyme replacement therapy or small pharmacological chaperones in patients carrying amenable pathogenic GLA gene variants and more general management of cardiac symptoms and complications. In this paper, we summarize current knowledge of FD-related heart disease and expert consensus recommendations for its management.

Cardiomyopathy in Children: Classification and Diagnosis: A Scientific Statement From the American Heart Association

In this scientific statement from the American Heart Association, experts in the field of cardiomyopathy (heart muscle disease) in children address 2 issues: the most current understanding of the causes of cardiomyopathy in children and the optimal approaches to diagnosis cardiomyopathy in children. Cardiomyopathies result in some of the worst pediatric cardiology outcomes; nearly 40% of children who present with symptomatic cardiomyopathy undergo a heart transplantation or die within the first 2 years after diagnosis. The percentage of children with cardiomyopathy who underwent a heart transplantation has not declined over the past 10 years, and cardiomyopathy remains the leading cause of transplantation for children >1 year of age. Studies from the National Heart, Lung, and Blood Institute-funded Pediatric Cardiomyopathy Registry have shown that causes are established in very few children with cardiomyopathy, yet genetic causes are likely to be present in most. The incidence of pediatric cardiomyopathy is ≈1 per 100 000 children. This is comparable to the incidence of such childhood cancers as lymphoma, Wilms tumor, and neuroblastoma. However, the published research and scientific conferences focused on pediatric cardiomyopathy are sparcer than for those cancers. The aim of the statement is to focus on the diagnosis and classification of cardiomyopathy. We anticipate that this report will help shape the future research priorities in this set of diseases to achieve earlier diagnosis, improved clinical outcomes, and better quality of life for these children and their families.

A Case of a 50-Year-Old Woman with Typical Fabry Disease Who Showed Serial Electrocardiographic and Echocardiographic Changes over a 17-Year Period

Fabry disease (FD) is a progressive, X-linked lysosomal storage disorder caused by a deficiency of α-galactosidase A activity. Affected individuals accumulate globotriaosylceramide and glycosphingolipids in the lysosomes and cytoplasm of cells throughout the body, leading to major organ failure and premature death. Cardiac involvement includes left ventricular hypertrophy, arrhythmia, endothelial dysfunction at vascular wall, and cardiomyopathy. The diagnosis of FD can be difficult and there is often a long lag time between symptoms and diagnosis. Here, we present a case of a 50-year-old woman with typical Fabry disease who showed serial electrocardiographic and echocardiographic changes over 17 years prior to diagnosis with Fabry disease.

Comparison of Native T1, Strain, and Traditional Measures of Cardiovascular Structure and Function by Cardiac Magnetic Resonance Imaging in Patients With Anderson-Fabry Disease

Cardiovascular magnetic resonance imaging (CMR) has emerged as a powerful tool to illuminate cardiovascular pathology in Anderson-Fabry disease (AFD); however, further study is required to develop clinically useful monitoring paradigms. The objective of this study was to retrospectively evaluate strain, native septal T1 values, and standard CMR measurements in a cohort of AFD patients to characterize useful measures of cardiovascular dysfunction that may be derived from a CMR platform. Eighteen patients were identified (n = 8 males) and divided according to presence or absence of left ventricular hypertrophy (LVH). Biometric data were gathered and native T1 and strain values were measured for all patients. Patients with LVH were older and had significantly lower native T1 measured at the apical septal (893 ± 78 vs 1044 ± 217 ms, p = 0.035), midventricular septal (864 ± 76 vs 988 ± 67 ms, p = 0.016), and basal septal (867 ± 58 vs 1027 ± 84 ms, p = 0.006) regions. Circumferential strain was more positive in patients with LVH (-13.5% ± 5.0% vs -18.7% ± 2.7%, p = 0.042), but longitudinal strain was not significantly different between groups. Patients with LVH had higher stroke volumes (114.5 ± 9.7 vs 96.7 ± 17.8 ml, p = 0.050), but other standard CMR measures were not significantly different. In conclusion, AFD patients with LVH have reduced native T1 and more positive circumferential strain compared to those without. The basal septum may be an appropriate region for standard measure of native T1 in this population.

α-Galactosidase A-deficient rats accumulate glycosphingolipids and develop cardiorenal phenotypes of Fabry disease

Fabry disease is an X-linked lysosomal storage disease caused by α-galactosidase A (α-Gal A) deficiency. Kidney and heart failure are frequent complications in adulthood and greatly contribute to patient morbidity and mortality. Because α-Gal A-deficient mouse models do not recapitulate cardiorenal findings observed in patients, a nonmouse model may be beneficial to our understanding of disease pathogenesis. In this study, we evaluated disease processes in a recently generated Fabry rat model. We found that male Fabry rats weighed significantly less than wild-type (WT) males, whereas female Fabry rats weighed significantly more than WT females. Whereas no difference in female survival was detected, we observed that male Fabry rats had a decreased lifespan. Skin histology revealed that inflammation and lipoatrophy may be chief disease mediators in patients. With respect to the kidney and heart, we found that both organs accumulate α-Gal A substrates, including the established biomarkers, globotriaosylceramide and globotriaosylsphingosine. Longitudinal serum and urine chemistry panels demonstrated pronounced renal tubule dysfunction, which was confirmed histologically. Mitral valve thickening was observed in Fabry rats using echocardiography. We conclude that Fabry rats recapitulate important kidney and heart phenotypes experienced by patients and can be further used to study disease mechanisms and test therapies.-Miller, J. J., Aoki, K., Mascari, C. A., Beltrame, A. K., Sokumbi, O., North, P. E., Tiemeyer, M., Kriegel, A. J., Dahms, N. M., α-Galactosidase A-deficient rats accumulate glycosphingolipids and develop cardiorenal phenotypes of Fabry disease.

Genetic Infiltrative Cardiomyopathies

Infiltrative cardiomyopathies are characterized by abnormal accumulation or deposition of substances in cardiac tissue leading to cardiac dysfunction. These can be inherited, resulting from mutations in specific genes, which engender a diverse array of extracardiac features but overlapping cardiac phenotypes. This article provides an overview of each inherited infiltrative cardiomyopathy, describing the causative genes, the pathologic mechanisms involved, the resulting cardiac manifestations, and the therapies currently offered or being developed.

Arrhythmia and Clinical Cardiac Findings in Children With Anderson-Fabry Disease

Anderson-Fabry Disease (AFD) is a lysosomal storage disorder that results in progressive cardiovascular hypertrophy, scarring, and arrhythmia burden; yet, the early cardiac phenotype of AFD is still poorly defined. To further characterize early cardiac features in AFD, we evaluated electrocardiographic and clinical findings contained in a local cohort of pediatric AFD patients and arrhythmia data in children enrolled in the Fabry Registry. Twenty-six local patients aged <18 years were identified (average age 9.7 ± 3.8 years, n = 12 males). Sinus bradycardia was the most frequent rhythm abnormality (23%), followed by ectopic atrial rhythm (12%) and premature atrial contractions (8%). No PR, QRS, or QTc intervals were prolonged. First-degree atrioventricular block developed in 1 female during follow-up. Chest pain (35%) and palpitations (23%) were highly prevalent complaints in clinical follow-up and did not differ significantly between genders. Structural findings included aortic root dilation in 3 patients and concurrent aortic insufficiency in 1. Among 593 patients aged < 18 years with electrocardiographic data identified in the Fabry Registry, sinus bradycardia, defined as heart rate <60 beats per minute per registry guidelines, was the most common arrhythmia (12.3%). In conclusion, clinical findings and subtle abnormalities of conduction, rhythm, and structure point toward a heterogeneous inception of Fabry cardiomyopathy. Bradycardia, common in adults, is frequent even among children with AFD. Given the potential for early initiation of enzyme replacement therapy to reduce cardiovascular morbidity, continued work to develop paradigms of therapy and longitudinal cardiovascular surveillance is warranted.

Fabry's disease: an example of cardiorenal syndrome type 5

Cardiorenal syndrome type 5 (CRS-5) includes conditions where there is a simultaneous involvement of the heart and kidney from a systemic disorder. This is a bilateral organ cross talk. Fabry's disease (FD) is a devastating progressive inborn error of metabolism with lysosomal glycosphingolipid deposition in variety of cell types, capillary endothelial cells, renal, cardiac and nerve cells. Basic effect is absent or deficient activity of lysosomal exoglycohydrolase a-galactosidase A. Renal involvement consists of proteinuria, isosthenuria, altered tubular function, presenting in second or third decade leading to azotemia and end-stage renal disease in third to fifth decade mainly due to irreversible changes to glomerular, tubular and vascular structures, especially highlighted by podocytes foot process effacement. Cardiac involvement consists of left ventricular hypertrophy, right ventricular hypertrophy, arrhythmias (sinus node and conduction system impairment), diastolic dysfunction, myocardial ischemia, infarction, transmural replacement fibrosis, congestive heart failure and cardiac death. Management of FD is based on enzymatic replacement therapy and control of renal (with anti-proteinuric agents such as angiotensin-converting enzyme inhibitors-and/or angiotensin II receptor blockers), brain (coated aspirin, clopidogrel and statin to prevent strokes) and heart complications (calcium channel blockers for ischemic cardiomyopathy, warfarin and amiodarone or cardioverter device for arrhythmias).

An open-label clinical trial of agalsidase alfa enzyme replacement therapy in children with Fabry disease who are naïve to enzyme replacement therapy

Background

Following a drug manufacturing process change, safety/efficacy of agalsidase alfa were evaluated in enzyme replacement therapy (ERT)-naïve children with Fabry disease.

Methods

In an open-label, multicenter, Phase II study (HGT-REP-084; Shire), 14 children aged ≥7 years received 0.2 mg/kg agalsidase alfa every other week for 55 weeks. Primary endpoints: safety, changes in autonomic function (2-hour Holter monitoring). Secondary endpoints: estimated glomerular filtration rate, left ventricular mass index (LVMI), midwall fractional shortening, pharmacodynamic parameters, and patient-reported quality-of-life.

Results

Among five boys (median 10.2 [range 6.7, 14.4] years) and nine girls (14.8 [10.1, 15.9] years), eight patients experienced infusion-related adverse events (vomiting, n=4; nausea, n=3; dyspnea, n=3; chest discomfort, n=2; chills, n=2; dizziness, n=2; headache, n=2). One of these had several hypersensitivity episodes. However, no patient discontinued for safety reasons and no serious adverse events occurred. One boy developed immunoglobulin G (IgG) and neutralizing antidrug antibodies. Overall, no deterioration in cardiac function was observed in seven patients with low/abnormal SDNN (standard deviation of all filtered RR intervals; <100 ms) and no left ventricular hypertrophy: mean (SD) baseline SDNN, 81.6 (20.9) ms; mean (95% confidence interval [CI]) change from baseline to week 55, 17.4 (2.9, 31.9) ms. Changes in SDNN correlated with changes in LVMI (r=−0.975). No change occurred in secondary efficacy endpoints: mean (95% CI) change from baseline at week 55 in LVMI, 0.16 (−3.3, 3.7) g/m^2.7; midwall fractional shortening, −0.62% (−2.7%, 1.5%); estimated glomerular filtration rate, 0.15 (−11.4, 11.7) mL/min/1.73 m²; urine protein, −1.8 (−6.0, 2.4) mg/dL; urine microalbumin, 0.6 (−0.5, 1.7) mg/dL; plasma globotriaosylceramide (Gb₃), −5.71 (−10.8, −0.6) nmol/mL; urinary Gb₃, −1,403.3 (−3,714.0, 907.4) nmol/g creatinine, or clinical quality-of-life outcomes.

Conclusion

Fifty-five weeks’ agalsidase alfa ERT at 0.2 mg/kg every other week was well tolerated. Disease progression may be slowed when ERT is started prior to major organ dysfunction.

Trial registration

https://ClinicalTrials.gov identifier NCT01363492.

Paediatric Fabry disease

Fabry disease is a rare, progressive X-linked inborn error of the glycosphingolipid metabolic pathway. Mutations of the GLA gene result in deficiency of the lysosomal enzyme, α-galactosidase A (α-Gal A) with accumulation of glycosphingolipids, particularly globotriaosylceramide (GL3) in the vascular endothelium of various tissues. Accumulation of GL3 eventually leads to life threatening renal, cardiac and cerebrovascular complications typically in the third to fifth decades of life. The first signs and symptoms of classic Fabry disease however appear in childhood but diagnosis is often delayed. The symptoms most commonly experienced in childhood include neuropathic pain, gastrointestinal dysfunction, hyperhidrosis and heat intolerance. Timely diagnosis is important as early treatment with enzyme replacement therapy reduces GL3 accumulation, can stabilize disease progression and potentially prevent irreversible organ damage. Physicians should be familiar with the signs and symptoms of Fabry disease in childhood and be particularly vigilant for unusual or non-specific but recurrent or episodic symptoms.

Anderson-Fabry cardiomyopathy: prevalence, pathophysiology, diagnosis and treatment

Anderson-Fabry disease (AFD) is a lysosomal storage disease caused by the inappropriate accumulation of globotriaosylceramide in tissues due to a deficiency in the enzyme α-galactosidase A (α-Gal A). Anderson-Fabry cardiomyopathy is characterized by structural, valvular, vascular and conduction abnormalities, and is now the most common cause of mortality in patients with AFD. Large-scale metabolic and genetic screening studies have revealed AFD to be prevalent in populations of diverse ethnic origins, and the variant form of AFD represents an unrecognized health burden. Anderson-Fabry disease is an X-linked disorder, and genetic testing is critical for the diagnosis of AFD in women. Echocardiography with strain imaging and cardiac magnetic resonance imaging using late enhancement and T1 mapping are important imaging tools. The current therapy for AFD is enzyme replacement therapy (ERT), which can reverse or prevent AFD progression, while gene therapy and the use of molecular chaperones represent promising novel therapies for AFD. Anderson-Fabry cardiomyopathy is an important and potentially reversible cause of heart failure that involves LVH, increased susceptibility to arrhythmias and valvular regurgitation. Genetic testing and cardiac MRI are important diagnostic tools, and AFD cardiomyopathy is treatable if ERT is introduced early.

Effectiveness of agalsidase alfa enzyme replacement in Fabry disease: cardiac outcomes after 10 years' treatment

BACKGROUND

To explore long-term effects of agalsidase alfa on Fabry disease cardiomyopathy in adults.

METHODS

Retrospective analysis of prospectively collected data at a single center in Mainz, Germany, revealed that 45 adult patients (21 men, 24 women) had received agalsidase alfa for approximately 10 years. Data were extracted for cardiac and heart failure status, echocardiographic evaluations of cardiac structure and function, and renal function at treatment start and during agalsidase alfa treatment.

RESULTS

After 10 years of agalsidase alfa treatment, heart failure classification had improved by at least 1 class in 22/42 patients, and angina scores were stable or improved in 41/42 patients. During treatment, no patients without left ventricular hypertrophy (LVH) at treatment initiation developed LVH, and no patients with LVH at treatment initiation showed a decline in left ventricular mass.

CONCLUSIONS

Approximately 10 years of agalsidase alfa treatment appeared to have beneficial effects for controlling progression and improving some symptoms of Fabry-associated cardiomyopathy.

Agalsidase alfa in pediatric patients with Fabry disease: a 6.5-year open-label follow-up study

Background

Signs and symptoms of the X-linked disorder, Fabry disease (FD), can occur early during childhood with heterogeneous clinical manifestations including potential cardiac and renal dysfunction. Several studies support the efficacy of the enzyme replacement therapy (ERT) agalsidase alfa, in adults with FD, though published data on the long-term safety and efficacy of agalsidase alfa in children are limited. As early treatment with ERT has the potential to reduce complications arising from disease progression, children in particular could benefit. The objective of this study was to evaluate the safety and efficacy of long-term agalsidase alfa ERT in children with FD.

Methods

TKT029 was a 6.5-year open-label, multicenter, extension study of children who completed TKT023 (26-week, open-label, every-other-week, intravenous 0.2 mg/kg agalsidase alfa). TKT029 was divided into two phases (before and after an agalsidase alfa manufacturing process change); only patients who participated in both phases were included in the analysis. Primary endpoints included safety, tolerability, and heart rate variability (HRV). Additional efficacy parameters included left ventricular mass index (LVMI), estimated glomerular filtration rate (eGFR), and plasma/urine globotriaosylceramide (Gb₃).

Results

Eleven patients participated (phase 1 baseline median [range] age: 10.8 [8.6–17.3] years; 10 [90.9%] males). During TKT029 (6.5 years), all patients experienced ≥1 treatment-emergent adverse event (AE); eight patients had ≥1 possibly/probably drug-related AE. Six patients experienced infusion-related AEs, but none discontinued due to AEs. Eight serious AEs arose (two patients); none were deemed drug-related. No deaths occurred. Three patients developed anti-agalsidase alfa antibodies, with IgG antibodies in one patient that were agalsidase alfa neutralizing, but without apparent clinical impact. Renal (eGFR) endpoints remained generally in normal range. Cardiac endpoints remained stable within normal range for LVMI and a trend towards improved HRV, although some patients experienced a reduction in heart rate. Plasma and urinary Gb₃ reductions were maintained.

Conclusions

TKT029 represents the longest assessment of ERT in children with FD in a clinical trial setting. Overall, agalsidase alfa was well tolerated and demonstrated a stabilizing clinical effect. Agalsidase alfa may be a useful clinical therapeutic option for long-term treatment initiated during childhood in patients with FD.

Trial registration

http://ClinicalTrials.gov identifier NCT00084084.

Electronic supplementary material

The online version of this article (doi:10.1186/s13023-014-0169-6) contains supplementary material, which is available to authorized users.

Delphi consensus on the current clinical and therapeutic knowledge on Anderson-Fabry disease

BACKGROUND

Management of Anderson-Fabry disease (AFD) is contentious, particularly regarding enzyme replacement therapy (ERT). We report results of a Delphi consensus panel on AFD management.

METHODS

A survey to gauge consensus among AFD experts was distributed online and responses were analysed. Statements on: 1) diagnosis; 2) when starting ERT; 3) management of ERT infusion and adverse reactions; and 4) follow-up/monitoring response to therapy and progression of disease were included. Responses without consensus were discussed with an enlarged panel and modified to reach consensus.

RESULTS

15 experts responded to the survey. After plenary discussion among the enlarged panel, consensus was reached on most statements. Key points were the use of a target organ biopsy to show Gb3 deposits in symptomatic women with negative molecular analysis, the need for ERT in symptomatic women and in all patients with persistent signs and symptoms ± organ damage. It was agreed to assess vital signs before ERT administration and use a 0.2 μL filter on infusion to reduce the risk of adverse reactions, that serum should be drawn prior to the first infusion for anti-agalsidase antibody analysis to have a baseline value if a subsequent adverse reaction appears, and that pre-medication is required in those with prior infusion reactions. Holter ECG monitoring, cardiac and brain MRI, renal parameters, and abdominal ultrasound were considered important for the assessment of disease progression and response at ERT.

CONCLUSIONS

This consensus supplies guidance to healthcare providers on best practice in the management of patients with AFD and indicates a need for more guidance.

Fabry disease in infancy and early childhood: a systematic literature review

PURPOSE

Fabry disease is a pan-ethnic, progressive, X-linked genetic disorder that commonly presents in childhood and is caused by deficient activity of the lysosomal enzyme alpha-galactosidaseA (α-gal A). Symptoms of Fabry disease in the pediatric population are well described for patients over five years of age; however, data are limited for infancy and early childhood. The purpose of this article is to delineate the age of detection for specific Fabry symptoms in early childhood.

METHODS

A systematic retrospective analysis of PubMed indexed, peer-reviewed publications and case reports in the pediatric Fabry population was performed to review symptoms in patients reported before 5 years of age.

RESULTS

The most frequently reported symptom in all age groups under 5 years was acroparesthesias/neuropathic pain, reported in 9 children, ranging in age from 2.0-4.0 years. Also notable is the frequency of gastrointestinal issues reported in 6 children aged 1.0-4.1 years of age.

CONCLUSION

This article finds clear evidence that symptoms can occur in early childhood, before age 5 years. Given early presenting symptoms and the ability to monitor these disease hallmarks, a timely referral to a medical geneticist or other specialty clinician experienced in managing children with Fabry disease is strongly indicated.

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

OBJECTIVE

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

DESIGN

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

DATA EXTRACTION

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

RESULTS

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

CONCLUSION

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

Renal complications of Fabry disease in children

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

Early cardiac changes in children with anderson-fabry disease

OBJECTIVE

Limited evidence is available about the early cardiac manifestation of Fabry disease (FD) in children. We aimed to evaluate cardiac involvement in children with FD by analysing serial structural and electrocardiographic changes.

METHODS

The data were acquired from 22 children with FD [11 males; median age 9.8 (ranging 2.5-16) years]. Seven patients (5 males) were on enzyme replacement therapy (ERT) with Agalasidase alpha. Echocardiography, ECG and 24-h ECG monitoring recordings were acquired during routine annual clinical controls. ECG data were compared to a group of age-and gender-matched controls.

RESULTS

At baseline, ECG and ECHO parameters of left ventricular mass were similar in both males and females. Three boys (all were on ERT) developed left ventricular hypertrophy (LVH) during two-year follow-up. The progression to LVH was accompanied by the appearance of frequent ventricular premature beats in two cases and supraventricular premature beats (SPBs) with T wave inversion in one case. T wave inversion and SPBs were detected in two younger relatives of a patient with LVH, in the absence of detectable LVH. Seven out of 22 patients had T wave abnormalities. Five of them were males (p = 0.03) all carrying the N215S mutation (p = 0.03). At baseline, median PR intervals were prolonged in FD subjects compared to controls [143 (122-177) vs. 122 (82-165) ms; p < 0.0001].

CONCLUSIONS

Cardiac complications of FD become apparent in childhood as subtle changes with slow but detectable progression over time, with males more frequently affected than females. Progression of LVH was apparent in three children despite ERT.

Genetics and metabolic cardiomyopathies

Metabolic disorders encompass a heterogeneous group of conditions that commonly affect the heart and contribute adversely to cardiovascular outcomes. As the heart is a metabolically active organ, inborn errors in metabolism (IEMs) often present with cardiac manifestations such as cardiomyopathy, arrhythmia, and valvular dysfunction. More than 40 IEMs are reported to cause cardiomyopathy, including fatty acid oxidation defects, glycogen, lysosomal and perioxisome storage diseases, mitochondrial cardiomyopathies, organic acidaemias, aminoacidopathies and congenital disorders of glycosylation. Studies suggest that IEM account for only 5% of cardiomyopathies; however, their diagnosis is imperative to enable the effective institution of disease-specific management strategies. This review describes the more common genetic defects that affect metabolic pathways and give rise to heart muscle disease.

Cardiac disease in children and young adults with various lysosomal storage diseases: Comparison of echocardiographic and ECG changes among clinical groups

BACKGROUND

Lysosomal storage disease (LSD) is a rare inherited disease group. Consecutively there are few data on cardiac changes in mucopolysaccharidosis (MPS), Anderson Fabry disease (AFD), and other LSD (oLSD) including Pompe disease (PD) and Danon disease (DD), I-cell disease ICD and mucolipidosis III (ML III).

METHODS

Between 1994 and 2011, we identified 39 patients with LSD: 25 with MPS, 8 with AFD, and 6 with oLSD including PD (1), ML III (2), DD (1), and ICD (2) at our institution fulfilling the inclusion criteria of at least one echocardiogram and ECG.

RESULTS

Median age was 11.4 years (range: 2-27), 22 were females (56%). Normal echocardiograms were present in 12 patients (31%): 4 with MPS (16%), 7 AFD (88%), and 1 oLSD (17%). Valvular heart disease was present in 23 patients (59%) occurring more often in MPS (76%) and oLSD (67%) than in AFD (0%) (p < 0.001). The most common ECG abnormality was a short PR interval in 10 of 35 patients (29%) occurring in all LSD groups. Median follow-up was 5.8 (0.2-22.2) years showing diminished 5-year survival compared to an age-matched group. However, no patient died due to a cardiac cause and no cardiovascular intervention was necessary.

CONCLUSION

Echocardiographically detectable cardiovascular involvement in children with LSD is mostly confined to MPS and oLSD. Valve thickening in echo and a short PR interval in the ECG are the most frequent abnormalities. Routine repeat assessment is recommended in LSD. However, significant cardiac disease necessitating cardiac intervention is rare during a short follow-up.

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

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

Small fiber neuropathy in Fabry disease

Previous studies have explicitly shown that small nerve fibers are affected in Fabry disease which is assumed to cause the severe neuropathic pain that patients may have from childhood on. Neuropathic pain and small fiber neuropathy characteristics have therefore been considered as appropriate study endpoints in studies on the efficacy of enzyme replacement therapy. However, the relationship between small fiber neuropathy characteristics and pain, as well as the course of small fiber neuropathy in Fabry disease is still uncertain. In this article a comprehensive overview of the existing literature on small nerve fiber function and structure and the relationship with pain, age and disease severity is presented supplemented with data from the Dutch Fabry cohort, with the aim to identify consensus as well as controversies and to propose a hypothesis on the evolution of neuropathy in Fabry disease.

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

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

Update on role of agalsidase alfa in management of Fabry disease

Fabry disease (FD) is an X-linked lysosomal storage disorder that affects both men and women. The manifestations of this heterogeneous disease are multisystemic and progressive. Prior to the development of enzyme replacement therapy, the management and treatment for Fabry disease was largely nonspecific and supportive. Because enzyme replacement therapy became commercially available in 2001, a variety of clinical benefits in Fabry patients have been consistently reported, including improved renal pathology and cardiac function, and reduced severity of neuropathic pain and improved pain-related quality of life. This update focuses on published data on the efficacy and tolerability of enzyme replacement therapy with agalsidase alfa, and gives a brief overview on some of the outstanding management issues in the treatment of this complex disease.

Enzyme replacement therapy for Fabry disease: some answers but more questions

Fabry disease (FD) is a multisystem, X-linked disorder of glycosphingolipid metabolism caused by enzyme deficiency of α-galactosidase A. Affected patients have symptoms including acroparesthesias, angiokeratomas, and hypohidrosis. More serious manifestations include debilitating pain and gastrointestinal symptoms, proteinuria and gradual deterioration of renal function leading to end-stage renal disease, hypertrophic cardiomyopathy, and stroke. Heterozygous females may have symptoms as severe as males with the classic phenotype. Before 2001, treatment of patients with FD was supportive. The successful development of enzyme replacement therapy (ERT) has been a great advancement in the treatment of patients with FD and can stabilize renal function and cardiac size, as well as improve pain and quality of life of patients with FD. In this review, we have provided a critical appraisal of the literature on the effects of ERT for FD. This analysis shows that data available on the treatment of FD are often derived from studies which are not controlled, rely on surrogate markers, and are of insufficient power to detect differences on hard clinical endpoints. Further studies of higher quality are needed to answer the questions that remain concerning the efficacy of ERT for FD.

Effects of enzyme replacement therapy in Fabry disease--a comprehensive review of the medical literature

Enzyme replacement therapy with α-galactosidase A has been used to treat Fabry disease since 2001. This article reviews the published evidence for clinical efficacy of the two available enzyme preparations. We focused on heart, kidney, and nervous system manifestations, which impact both quality of life and overall prognosis. A literature search was undertaken to identify prospective open or randomized controlled trials of enzyme replacement therapy in patients with Fabry disease published since 2001. To date, no definitive conclusion can be drawn from studies that have directly compared therapeutic responses between the two commercially available enzyme preparations. Significant clinical benefits of enzyme replacement therapy have been demonstrated, mainly in patients at an early phase of the disease, with beneficial effects on heart, kidneys, pain, and quality of life in treated patients. Incidence of antibodies against agalsidase alfa and agalsidase beta observed during major clinical studies suggests a greater antigenic response to agalsidase beta. Further studies are required to confirm the long-term clinical benefits of enzyme replacement therapy. More studies with female patients are needed as are investigations of early initiation of enzyme replacement therapy to determine the optimal time to start treatment to prevent irreversible organ damage. The value of adjunctive and supportive therapies should also be rigorously analyzed.