The heart in Fabry's disease. A histochemical and electron microscopic study

Diagnostic value of papillary muscle hypertrophy and mitral valve thickness to discriminate cardiac amyloidosis and Fabry disease

BACKGROUND

Cardiac amyloidosis (CA) and Fabry disease (FD) cause myocardial damage but may also affect the valvular and subvalvular apparatus. We aimed to evaluate the diagnostic accuracy of new echocardiographic indices including mitral valve thickness and papillary muscle (PM) hypertrophy to differentiate CA and FD.

METHODS

In patients with confirmed CA and FD, a detailed assessment of valvular function, mitral valve leaflet thickness and PM area as well as PM left ventricular area ratio (PM/LV-ratio) was performed in offline analyses. Receiver operating characteristic curve analyses were conducted to determine the diagnostic accuracy of mitral valve thickness, PM hypertrophy, and PM/LV-ratio to distinguish CA from FD.

RESULTS

We retrospectively analyzed a cohort of 129 patients (FD n = 49, CA n = 80). CA patients showed significantly more thickened mitral valve leaflets (4.1 ± 1.3 mm vs. 2.9 ± 1.1 mm, p < 0.001) and a higher PM area [4.0 (3.1-4.6) mm2 vs. 2.8 (2.1-4.6) mm2, p = 0.009] with a comparable PM/LV-ratio in both groups. Mitral valve thickness showed the highest diagnostic accuracy to discriminate CA [AUC 0.77 (95% CI 0.67-0.87)]. The prevalence of aortic, tricuspid, and pulmonary valve regurgitation was significantly higher in CA (aortic regurgitation ≥ II° 13% vs. 4%, tricuspid regurgitation≥ II° 19% vs. 8%, p < 0.001).

CONCLUSION

Our results suggest that the assessment of mitral valve thickness may be a new useful echocardiographic parameter to differentiate CA and FD, whereas papillary muscle hypertrophy and PM/LV-ratio showed a limited diagnostic performance to discriminate CA. German clinical trials registry: DRKS00027403.

Right Ventricular Myocardial Involvement in Anderson-Fabry Disease at Diagnosis: Evaluation with Three-Dimensional Strain Imaging

Background: Right ventricular (RV) involvement in Anderson-Fabry disease (AFD) is well known in the advanced stages of the disease RV hypertrophies, but little is known about the early involvement. The aim of our study was to assess RV function in AFD patients at diagnosis. Methods: A total of 23 AFD patients and 15 controls comparable for age and sex were recruited. A complete 2D standard echo with 3D volumetric and strain analysis of RV was performed. Results: Two patient populations, comparable for clinical baseline characteristics were considered. RV free wall thickness was significantly increased in the AFD group. No significant differences in standard RV indices (TAPSE, transverse diameter, tissue Doppler velocities of the lateral tricuspid annulus) were found. A 3D volumetric analysis showed reduced RV ejection fraction and lower values of longitudinal septal, free wall and global longitudinal strain (GLS) in AFD patients. RV free wall thickness significantly correlated with both free wall RV LS and RV GLS. In multiple linear regression analysis, RV free wall thickness was independently associated with RV GLS even after correction for age and heart rate. Conclusions: In AFD patients, 3D echocardiography allows for the identification of early subclinical functional impairment of RV. RV dysfunction is independently associated with RV hypertrophy.

Left atrial strain correlates with severity of cardiac involvement in Anderson-Fabry disease

OBJECTIVES

Cardiac involvement in Anderson-Fabry disease (AFD) results in myocardial lipid depositions. An early diagnosis can maximize therapeutic benefit. Thus, this study aims to investigate the potential of cardiac MRI (CMR) based parameters of left atrial (LA) function and strain to detect early stages of AFD.

METHODS

Patients (n = 58, age 40 (29-51) years, 31 female) with genetically proven AFD had undergone CMR including left ventricular (LV) volumetry, mass index (LVMi), T1, and late gadolinium enhancement, complemented by LA and LV strain measurements and atrial emptying fractions. Patients were stratified into three disease phases and compared to age and sex-matched healthy controls (HC, n = 58, age 41 [26-56] years, 31 female).

RESULTS

A total of 19 early-, 20 intermediate-, and 19 advanced-phase patients were included. LV and LA reservoir strain was significantly impaired in all AFD phases, including early disease (both p < 0.001). In contrast, LA volumetry, T1, and LVMi showed no significant differences between the early phase and HC (p > 0.05). In the intermediate phase, LVMi and T1 demonstrated significant differences. In advanced phase, all parameters except active emptying fractions differed significantly from HC. ROC curve analyses of early disease phases revealed superior diagnostic confidence for the LA reservoir strain (AUC 0.88, sensitivity 89%, specificity 75%) over the LV strain (AUC 0.82).

CONCLUSIONS

LA reservoir strain showed impairment in early AFD and significantly correlated with disease severity. The novel approach performed better in identifying early disease than the established approach using LVMi and T1. Further studies are needed to evaluate whether these results justify earlier initiation of therapy and help minimize cardiac complications.

KEY POINTS

• Parameters of left atrial function and deformation showed impairments in the early stages of Anderson-Fabry disease and correlated significantly with the severity of Anderson-Fabry disease. • Left atrial reservoir strain performed superior to ventricular strain in detecting early myocardial involvement in Anderson-Fabry disease and improved diagnostic accuracies of approaches already using ventricular strain. • Further studies are needed to evaluate whether earlier initiation of enzyme replacement therapy based on these results can help minimize cardiac complications from Anderson-Fabry disease.

Clinical relevance of globotriaosylceramide accumulation in Fabry disease and the effect of agalsidase beta in affected tissues

Fabry disease (FD) is a rare lysosomal storage disorder, characterized by a reduction in α-galactosidase A enzyme activity and the progressive accumulation of globotriaosylceramide (GL3) and its metabolites in the cells of various organs. Agalsidase beta, an enzyme replacement therapy (ERT), is approved for use in patients with FD in Europe, Canada, Australia, South America, and Asia, and is the only ERT approved for use in the United States. In this review, we discuss the clinical relevance of GL3 accumulation, the effect of agalsidase beta on GL3 in target tissues, and the association between treatment-related tissue GL3 clearance and long-term structure, function, or clinical outcomes. Accumulation of GL3 in the kidney, heart, vasculature, neurons, skin, gastrointestinal tract and auditory system correlates to cellular damage and irreversible organ damage, as a result of sclerosis, fibrosis, apoptosis, inflammation, and endothelial dysfunction. Damage leads to renal dysfunction and end-stage renal disease; myocardial hypertrophy with heart failure and arrhythmias; ischemic stroke; neuropathic pain; skin lesions; intestinal ischemia and dysmotility; and hearing loss. Treatment with agalsidase beta is effective in substantially clearing GL3 in a range of cells from the tissues affected by FD. Agalsidase beta has also been shown to slow renal decline and lower the overall risk of clinical progression, demonstrating an indirect link between treatment-related GL3 clearance and stabilization of FD.

Cardiac Imaging in Anderson-Fabry Disease: Past, Present and Future

Anderson-Fabrydisease is an X-linked lysosomal storage disorder caused by a deficiency in the lysosomal enzyme α-galactosidase A. This results in pathological accumulation of glycosphingolipids in several tissues and multi-organ progressive dysfunction. The typical clinical phenotype of Anderson-Fabry cardiomyopathy is progressive hypertrophic cardiomyopathy associated with rhythm and conduction disturbances. Cardiac imaging plays a key role in the evaluation and management of Anderson-Fabry disease patients. The present review highlights the value and perspectives of standard and advanced cardiovascular imaging in Anderson-Fabry disease.

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.

Diverse phenotypic expression associated with the same genetic variant in female heterozygote patients of Anderson–Fabry disease: a case series

Background

Anderson–Fabry disease (AFD) is an X-linked lysosomal storage disorder resulting from a mutation of alpha-galactosidase A gene (GLA), causing deficiency in alpha-galactosidase activity. The enzyme deficit can lead to storage of globotriaosylceramide in various organs including heart. Studies suggest that vasospastic angina (VSA) is associated with AFD.

Case summary

This clinical case series aimed to present two female patients with AFD, including progressive cardiac involvement: a 50-year-old woman (patient number 1) and a 39-year-old woman (patient number 2) who are siblings with a male AFD patient harbouring p. Arg342Glu missense variant in alpha-galactosidase A gene (GLA), who suffered VSA and subsequent ventricular fibrillation. Enzymatic tests and genetic analysis confirmed AFD in both female patients and histological tests revealed globotriaosylceramide deposits in their hearts. In patient number 1, a 12-lead electrocardiography and transthoracic echocardiography revealed cardiac hypertrophy. Coronary angiography revealed no organic coronary artery stenosis and vasospasms was induced by spasm provocation test. In patient number 2, no signs of cardiac hypertrophy were found, and coronary arteries had no organic stenosis with negative spasm provocation test. Both patients received enalapril therapy and enzyme replacement therapy (ERT).

Discussion

Different phenotype of AFD was occurred even with the same genetic variant in female heterozygote patients. The duration of exposing accumulation of Gb3 might affect cardiac hypertrophy and vasospasms. Coronary angiography with acetylcholine provocation test should be considered in female AFD patient, especially in case with cardiac hypertrophy.

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.

Echocardiography in Infiltrative Cardiomyopathy

Left ventricular (LV) wall thickening can occur due to both physiological and pathological processes. Some LV wall thickening is caused by infiltrative cardiac deposition diseases - rare disorders from both inherited and acquired conditions, with varying systemic manifestations. They portend a poor prognosis and are generally not reversible except in rare circumstances when early diagnosis and treatment may alter the outcome (e.g., Fabry disease). Cardiac involvement is variable and depends on the degree of infiltration and type of infiltrate. These changes often lead to the development of abnormalities in both the relaxation and contractile function of the heart ultimately resulting in heart failure. Echocardiography is generally the first investigation of choice as it is easily available and gives valuable information about the thickness of the ventricular walls as well as systolic and diastolic function. It is also able to identify unique, characteristic features of the disease as well as detecting any haemodynamic sequelae. This review looks at the role of echocardiography in the diagnosis and prognosis of infiltrative cardiac deposition diseases.

Unexpectedly High Prevalence of Coronary Spastic Angina in Patients With Anderson-Fabry Disease

BACKGROUND

Although we and others have reported cases of patients with Anderson-Fabry disease (AFD) complicated by coronary spastic angina (CSA), the prevalence of CSA in these patients remains unknown. Methods and Results: We performed the acetylcholine-induced provocation test, according to the Japanese guidelines for the diagnosis and treatment of patients with CSA, in 9 consecutive patients having 5 independent AFD pedigrees. Coronary spasms were provoked in conjunction with symptoms and ECG ischemic changes in 8 of 9 (89%) patients with AFD.

CONCLUSIONS

We found an unexpectedly high prevalence of CSA in patients with AFD.

Relief of Left Ventricular Outflow Obstruction by Cibenzoline in a Patient With Fabry’s Disease

A 46-year-old man was admitted for further evaluation of exertional chest discomfort. One family member had experienced sudden death, and 2 others had died of heart failure, including 1 known to have had Fabry’s disease. The patient was also diagnosed with Fabry’s disease, based on reduced leukocyte a-galactosidase A activity, 2.0 nmol/mg protein/hour, as well as endomyocardial biopsy findings of marked sarcoplasmic vacuolization of cardiac muscle cells by light microscopy and lamellated “zebra bodies” in the cytoplasm shown by electron microscopy. Echocardiography disclosed marked left ventricular hypertrophy and systolic anterior motion of the mitral leaflets. On cardiac catheterization, a left ventricular peak systolic outflow gradient of 50 mm Hg was noted; this decreased to 10 mm Hg following intravenous administration of 100 mg of cibenzoline. It is imperative to recognize the existence of cases with Fabry’s disease associated with left ventricular outflow obstruction.

Onset and progression of the Anderson-Fabry disease related cardiomyopathy

BACKGROUND

Cardiac involvement is responsible for substantial morbidity and mortality in Anderson-Fabry disease (AFD). We sought to document its onset and progression in a population of male and female AFD patients.

METHODS

We performed a cross sectional echocardiographic study of a cohort of 177 male and female AFD patients with subsequent longitudinal follow-up of 76 patients (38 males and 38 females; mean follow-up 4.5 years) who did not receive enzyme replacement therapy.

RESULTS

In this population, aged 3.3 to 70.8 years, a strong correlation between age and left ventricular mass indexed (LVMi, g/m(2.7)) was found in both males and females (P<0.0001 for both). At the initial examination 48.6% of the male patients and 36.4% of the female patients were classified as having left ventricular hypertrophy (LVH). The cumulative prevalence of LVH peaked at age 40 years in males and 60 years in females. In patients with longitudinal follow-up, LVMi increased by 4.07+/-1.03 g/m(2.7) per year in males and by 2.31+/-0.81 g/m(2.7) in females (P<0.01, Wilcoxon rank sum). In patients with LVH at baseline, the median progression rate was 5.52 g/m(2.7) per year in males and by 1.80 g/m(2.7) in females (P=0.12).

CONCLUSION

AFD is associated with high prevalence of LVH in both genders. However, the age of onset is delayed in females and progression rate slower.

Cardiac manifestations of Anderson-Fabry disease in children and adolescents

AIM

Fabry disease (Fabry) is a rare X-linked disorder caused by a deficiency of the lysosomal enzyme alpha-galactosidase A. The progressive accumulation of the major substrate, globotriaosylceramide, leads to renal dysfunction and hypertrophic cardiomyopathy, which are reported to become apparent in the third decade. This study was performed to determine if signs of cardiac manifestations of Fabry are seen in younger Fabry patients.

METHODS

Twenty children and adolescents of <or=18 years of age with confirmed Fabry underwent a standard 12-lead electrocardiogram (ECG), a 2-h Holter ECG, blood pressure measurements and a two-dimensional echocardiogram. Follow-up examinations were conducted for 14 patients after a mean interval of 25.9 months.

RESULTS

At baseline, mean left ventricular mass (LVM) indexed to height (LVM/h(2.7)) was 45.0+/-2.3 and 47.0+/-3.4 g/m(2.7) in boys (n=8) and girls (n=12), respectively, and all patients had LVM/h(2.7) of >75th percentile of that in healthy controls. After a mean 26-month follow-up, 12 out of 14 patients (85.7%) showed a mean increase of 7.5+/-3.2 g/m(2.7) in LVM/h(2.7). Heart rate variability (HRV) analyses revealed that male, but not female, Fabry patients had significantly reduced HRV, reflecting a reduction in parasympathetic stimulation of the heart (p<0.05).

CONCLUSION

Cardiac involvement in children with Fabry is frequent and may progress even at young age.

α-Galactosidase A in Vascular Disease

Deficiency of alpha-galactosidase A (GLA) (Fabry disease) leads to the accumulation of glycosphingolipids in the vasculature leading to multiorgan pathology. In addition to well-described microvascular disease, deficiency of GLA is also characterized by premature macrovascular events such as stroke and possibly myocardial infarction. The mechanisms by which GLA may influence macrovascular disease are unclear. A mouse model of GLA deficiency has facilitated the study of glycosphingolipid metabolism abnormalities on macrovascular end points. This review addresses some of the potential pathways by which GLA deficiency may contribute to vascular complications.

Extracellular matrix turnover and disease severity in Anderson-Fabry disease

BACKGROUND

Anderson-Fabry Disease (AFD) is an inherited metabolic disease associated with premature death secondary to cardiovascular and renal disease. Patients with AFD develop progressive left ventricular (LV) remodelling and heart failure. We hypothesized that altered extracellular matrix (ECM) turnover contributes to the pathophysiology of cardiac disease in AFD.

METHODS AND RESULTS

Twenty-nine consecutive patients (44.1 +/- 11.7 years, 15 male) with AFD and 21 normal controls (39.7 +/- 11.3 years, 10 male) had serum analysed for matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of matrix metalloproteinase-1 and -2 (TIMP-1, TIMP-2). All patients underwent clinical assessment, echocardiography and Mainz Severity Score Index (MSSI) measurement, a validated severity score in AFD. MMP-9 levels were significantly higher in patients than controls (1003.8 +/- 337.8 ng/ml vs 576.7 +/- 276.3 ng/ml respectively, p < 0.001). There were no differences in TIMP levels between patients and controls. There was a positive correlation between MMP-9 levels and MSSI (r = 0.5, p = 0.01). There was a negative correlation between MMP-9 and endocardial fractional shortening (FS) (r = -0.5, p = 0.01) and mid-wall FS (r = -0.6, p = 0.001). There was no correlation between other echocardiographic parameters and MMP-9 levels. These relations were independent of age and sex using stepwise linear regression analysis.

CONCLUSIONS

Patients with AFD have abnormal ECM turnover compared to normal controls. The correlation between MMP-9 levels and systolic function suggests that altered ECM turnover is important in cardiac remodelling. The association between MMP-9 and overall disease severity suggests that circulating levels of MMP-9 may provide a useful marker for assessing the response of patients with AFD to enzyme replacement treatment.

Enzyme-replacement therapy with agalsidase alfa in children with Fabry disease

CONTEXT

Fabry disease is an X-linked multisystem disorder. Enzyme-replacement therapy in adults has limited efficacy in treating major sequelae of advanced Fabry disease, such as kidney failure or stroke. This prompted a study of the safety and efficacy of enzyme replacement at an earlier stage of Fabry disease.

OBJECTIVES

Our purpose with this work was to evaluate safety and to explore efficacy of enzyme treatment with agalsidase alfa in pediatric patients with Fabry disease.

METHODS

We conducted a 6-month open-label study at 3 tertiary care centers with 24 children (19 boys and 5 girls) with a mean age of 11.8 (range: 6.5-18) years, to examine safety parameters, including infusion reactions and antiagalsidase alfa antibodies.

RESULTS

Agalsidase alfa was well tolerated, and all of the patients completed the study. Six boys and 1 girl had mild-to-moderate infusion reactions. One boy developed transient immunoglobulin G antibodies against agalsidase alfa. The boys showed a significant reduction in plasma globotriaosylceramide on treatment. Mean estimated glomerular filtration rate, cardiac structure, and function were normal and did not change over 26 weeks. Heart rate variability, as determined by 2-hour ambulatory monitoring, was decreased in the boys compared with the girls at baseline. All indices of heart rate variability improved significantly in the boys. Three patients with anhidrosis, as determined by quantitative sudomotor axon reflex testing, developed sweating. Six of 11 patients could reduce or cease their use of antineuropathic analgesics.

CONCLUSIONS

Enzyme replacement with agalsidase alfa was safe in this study. The exploratory efficacy analysis documented increased clearance of globotriaosylceramide and improvement of autonomic function. Prospective long-term studies are needed to assess whether enzyme replacement initiated early in patients with Fabry disease is able to prevent major organ failure in adulthood.

Histologic and electron microscopy findings in myocardium of treated Fabry disease

The well-described histologic and electron microscopic findings in Fabry disease cardiomyopathy are hypertrophic vacuolated cells with electron dense concentric lamellar bodies. We present altered findings in an endomyocardial biopsy from a patient with treated Fabry disease. A 51-year-old male with Fabry disease, treated with recombinant alpha-galactosidase enzyme replacement therapy for over 18 months, underwent an endomyocardial biopsy for heart failure. The histologic changes showed widespread hypertrophy and vacuolization with rare eosinophilic bodies. Electron microscopy failed to reveal the characteristic globotriaosylceramide concentric lamellar bodies (myelin figures) in the sarcoplasm. Instead, extensive aggregates and single tubular crystalline structures, giant secondary lysosomes as well as abnormal branched chain glycogen were present. This is the first histologic description of long-standing treated Fabry disease in cardiac myocytes.

Quantitative evaluation of sphingolipids using delayed extraction matrix-assisted laser desorption ionization time-of-flight mass spectrometry with sphingosylphosphorylcholine as an internal standard

Fabry disease is a glycolipid storage disorder caused by a defect of alpha-galactosidase A, and characterized by the systemic deposition of glycosphingolipids with terminal alpha-galactosyl moieties, mainly globotriaosylceramide, in tissues. Using delayed extraction matrix-assisted laser desorption ionization time-of-flight mass spectrometry (DE MALDI-TOF-MS), we analyzed the sphingolipids in the cardiac valves from a 49-year-old male patient with Fabry disease who suffered from congestive cardiac failure. Crude lipids were extracted from the cardiac valves with chloroform and methanol. After mild alkaline treatment of the crude lipids, a sphingolipid fraction was prepared and analyzed by DE MALDI-TOF-MS. The results were as follows: (a) ion peaks with m/z values corresponding to different ceramide trihexoside (CTH) species were detected; (b) with sphingosylphosphorylcholine (SPC) as the internal standard for semi-quantification of CTH, the relative peak height of CTH was calculated and plotted versus its amount loaded on the sample plate for MALDI-TOF-MS. The relative peak height of CTH with fatty acid C16:0 showed linearity between 0 and 50 ng CTH (regression coefficient, r>0.95); (c) semi-quantitative analysis revealed striking accumulation of CTH in the cardiac valves from the patient with Fabry disease. It was indicated that the accumulation of CTH in cardiac valves from Fabry disease patients can be detected with the DE MALDI-TOF-MS method. SPC is commercially available, and this semi-quantitative method involving MALDI-TOF-MS was found to be convenient, reliable and useful for CTH. It is expected to be applied to the quantification of CTH in small amounts of body fluids or other tissues and to clinical examination. It is also expected to be applicable to the quantification of other glycosphingolipids.

Long-term therapy with agalsidase alfa for Fabry disease: safety and effects on renal function in a home infusion setting

BACKGROUND

Fabry disease is an X-linked disorder of glycosphingolipid catabolism that is the result of an intracellular deficiency in the lysosomal enzyme alpha-galactosidase A (alpha-Gal A). This enzymatic defect results in the accumulation of globotriaosylceramide (Gb(3)) within cells and causes progressive neurological, cardiovascular and renal dysfunction. Our objective is to describe the safety and renal effects of long-term enzyme replacement therapy.

METHODS

This was a single centre, prospective open-label treatment trial in 25 adult male Fabry patients who had completed a 6-month randomized placebo-controlled study and subsequently enrolled in an open-label extension study. Patients were treated every other week with agalsidase alfa (0.2 mg/kg) infused intravenously over 40 min. The main outcome measures were safety, antibody response and renal glomerular filtration rate (GFR).

RESULTS

During the 4-4.5 years of enzyme replacement therapy, all eligible subjects were able to transition to home therapy. Eight patients developed persistent IgG antibodies to agalsidase alfa, but IgE antibodies were not detected in any patient. The development of IgG antibodies appeared not to affect any clinical end points. Estimated GFR remained stable in subgroups of patients with Stage I (GFR >90 ml/min) or Stage II (GFR 60-89 ml/min) chronic kidney disease at baseline. In contrast, in the subgroup of patients with Stage III chronic kidney disease (GFR 30-59 ml/min), the slope of the decline in GFR was reduced compared with comparable historical controls, suggesting that enzyme replacement therapy was slowing the decline of renal function in this susceptible population.

CONCLUSIONS

Long-term enzyme replacement therapy with agalsidase alfa is safe and may slow the progressive decline in renal function that was commonly observed in adult males with Fabry disease.

Prevalence and clinical significance of cardiac arrhythmia in Anderson-Fabry disease

Anderson-Fabry disease (AFD) is an X-linked lysosomal storage disorder caused by a deficiency in the enzyme alpha-galactosidase A. More than 60% of patients with AFD have evidence for cardiac involvement; the prevalence and clinical significance of arrhythmia in AFD are unknown. Seventy-eight consecutive patients (mean age 43.5 +/- 15.0 years, range 13.0 to 83.0; 43 men) with AFD were studied for 1.9 years (range 0.25 to 10). All patients underwent clinical evaluation, 12-lead electrocardiography, and echocardiography. Sixty patients (76.9%) underwent 24-hour ambulatory electrocardiographic monitoring. Persistent atrial fibrillation (AF) was present in 3 of 78 patients (3.9%); 8 (13.3%) had paroxysmal AF, and 5 (8.3%) had nonsustained ventricular tachycardia (VT). Patients with nonsustained VT were all men, with a maximal left ventricular (LV) wall thickness >20 mm. Age (p <0.001), left atrial diameter (p = 0.001), maximal LV wall thickness (p = 0.003), LV mass index (p = 0.009), and angina (p = 0.02) were univariate predictors of AF or paroxysmal AF. Using these predictors in a stepwise logistic regression analysis model, age was the only independent predictor of AF or paroxysmal AF (odds ratio 1.2, 95% confidence interval 1.1 to 1.3, p = 0.001). During follow-up, there was 1 sudden cardiac death, 4 patients received pacemakers for bradyarrhythmia, and 1 received a biventricular pacemaker and an internal cardioverter defibrillator. In conclusion, arrhythmias are common in older patients with AFD. The high incidence of pacemaker implantation and sudden cardiac death suggests that arrhythmia has a significant impact on the natural history of AFD.

Fabry disease and the heart: an overview of the natural history and the effect of enzyme replacement therapy

Fabry disease is a genetic disorder caused by the deficiency of alpha-galactosidase A, resulting in the lysosomal accumulation of glycosphingolipids. Fabry disease may result in cardiac, cerebral and renal complications. Cardiac abnormalities in patients with Fabry disease were first described in the 1960s. In the 1990s a form of Fabry disease confined to the heart was reported; however, this variant is extremely rare and a more appropriate concept is of cardiac predominance of the disease in some patients. Up to 60% of males with classic Fabry disease have cardiac abnormalities, including left ventricular hypertrophy, valvular dysfunction and conduction abnormalities. Recent data suggest that left ventricular mass and systolic function in patients with Fabry disease improve after 12 months of enzyme replacement therapy (ERT); however, many of the patients studied are relatively young and have mild cardiac abnormalities, suggesting that more research into the efficacy of ERT in older patients is necessary.

CONCLUSION

Cardiac manifestations are common in patients with Fabry disease and are not confined to a 'cardiac variant' of the disease.

α-Galactosidase A Deficiency Accelerates Atherosclerosis in Mice With Apolipoprotein E Deficiency

BACKGROUND

Alpha-galactosidase A (Gla) deficiency leads to widespread tissue accumulation of neutral glycosphingolipids and is associated with premature vascular complications such as myocardial infarction and stroke. Glycosphingolipids have been shown to accumulate in human atherosclerotic lesions, although their role in atherogenesis is unclear.

METHODS AND RESULTS

To determine whether Gla affects the progression of atherosclerosis, mice were generated with combined deficiencies of apolipoprotein E and Gla. At 45 weeks of age, Gla-deficient mice had developed more atherosclerosis than mice with normal Gla expression (25.1+/-14.0 versus 12.3+/-9.3 mm2 of total lesion area, P<0.02). This increase in atherosclerosis was associated with the presence of increased Gb3, enhanced inducible nitric oxide synthase expression, and increased nitrotyrosine staining.

CONCLUSIONS

These findings suggest that deficiency of Gla leads to increased inducible nitric oxide synthase expression and accelerated atherosclerosis.

Fabry disease: recognition and management of cutaneous manifestations

Fabry disease (angiokeratoma corporis diffusum universale) is a rare, X chromosome-linked lysosomal storage disease. The deficient enzyme, alpha-galactosidase A (alpha-gal A), is responsible for the accumulation of neutral glycosphingolipids within vascular endothelial lysosomes of various organs, including skin, kidneys, heart, and brain. The disease manifests primarily in affected hemizygous men and to some extent in heterozygous women ('carriers'). The diagnosis of Fabry disease is made in hemizygous males after the detection of the presence of angiokeratomas, irregularities in sweating, edema, scant body hair, painful sensations, and of cardiovascular, gastrointestinal, renal, ophthalmologic, phlebologic, and respiratory involvement. A deficiency of alpha-gal A in serum, leukocytes, tears, tissue specimens, or cultured skin fibroblasts further supports the diagnosis in male patients. Since heterozygous women show angiokeratomas in only about 30% of cases and may have alpha-gal A levels within normal range, genetic analysis is recommended. Current treatment of angiokeratomas of Fabry disease is based mainly on the use of laser systems, including variable pulse width 532nm Neodymium:Yttrium-Aluminum-Garnet (Nd:YAG) laser, 578nm copper vapor laser, and flashlamp-pumped dye laser. When cutaneous and mucous glands are affected, restrictions may be required with regard to the time spent in a warm climate and the amount time spent working or on sporting activities, and may necessitate the use of topical and systemic antiperspirant agents, and topical application of artificial lacrimal fluid and saliva, respectively. For the future, new treatment modalities, including enzyme replacement therapy, substrate deprivation strategies, and gene therapy offer extraordinary options for the cutaneous and visceral lesions in patients with Fabry disease.

Cardiac manifestations of Anderson-Fabry disease in heterozygous females

OBJECTIVES

We sought to define the prevalence of cardiac involvement in female patients with Anderson-Fabry disease (AFD).

BACKGROUND

Anderson-Fabry disease is a rare inborn X-linked lysosomal storage disorder. Globotriaosylceramide (Gb(3)), the major substrate of the deficient alpha-galactosidase A enzyme, accumulates progressively in vulnerable cells, including the cardiovascular system. It has been believed that heterozygous females have less cardiac involvement than hemizygous males with AFD.

METHODS

We performed two-dimensional echocardiographic examinations of female patients heterozygous for AFD.

RESULTS

Since 1997, a total of 55 female patients (mean age, 39.6 years; range, 6.1 to 70.8 years) with proven AFD have been investigated prospectively at our hospital. Of these, 13 (23.6%) had normal left ventricular (LV) geometry and LV mass (LVM). Seven patients (12.7%) had concentric remodeling, 29 patients (52.7%) concentric LV hypertrophy (LVH), and 6 patients (10.9%) eccentric LVH (2 with subaortic pressure gradients). There was a strong correlation between age and the severity of LVH (r(2) = 0.905; p < 0.0001), and all patients older than 45 years had LVH. With increasing LVM, there was a significant age-independent decrease in systolic and diastolic LV function. Mild thickening of the aortic valve leaflets was present in 25.5% of patients, with the same percentage demonstrating mild thickening of the mitral valve leaflets. Mild mitral valve prolapse was documented in 10.9% of patients.

CONCLUSIONS

Cardiac involvement, with LVH and structural valve abnormalities, is very common and worsens with age in females who are heterozygous for AFD, and they should therefore be considered candidates for enzyme replacement therapy.

Chloroquine cardiotoxicity: clinicopathologic features in three patients and comparison with three patients with Fabry disease

BACKGROUND

Microscopic features of chloroquine cardiotoxicity are similar to those of Fabry disease. The purpose of the study was to compare clinicopathologic findings in both disorders.

METHODS

Patients with a diagnosis of chloroquine cardiotoxicity or Fabry disease were identified who had undergone endomyocardial biopsy or autopsy at Mayo Clinic Rochester (1976-2000). Clinical information was collected from medical records and letters from referring physicians. Light and electron microscopy were performed in all cases.

RESULTS

Three patients (two women, one man) with chloroquine cardiotoxicity ranged in age from 53 to 73 years. Chloroquine was given for rheumatoid arthritis in two and systemic lupus erythematosus in one. Three patients (two men, one woman) with Fabry disease ranged in age from 58 to 76 years. Two had angiokeratomas, but only one had a previous diagnosis of Fabry disease. All six patients presented with dyspnea. Light microscopy from all six revealed myocyte enlargement due to perinuclear vacuolization. By transmission electron microscopy, all six showed abundant myelinoid figures within involved myocytes. Curvilinear bodies were observed in two patients with chloroquine cardiotoxicity and in none with Fabry disease.

CONCLUSIONS

Patients with cardiac dysfunction due to chloroquine cardiotoxicity or Fabry disease have similar ages, presenting clinical symptoms, cardiac light microscopy and sarcoplasmic myelinoid bodies ultrastructurally. Patients with Fabry disease may not have a personal or family history of the disease. Similarly, a history of chloroquine usage may not be known to the pathologist. In these settings, the presence of curvilinear bodies ultrastructurally is useful for the diagnosis of chloroquine cardiotoxicity.

Identification of four novel mutations in five unrelated Korean families with Fabry disease

Fabry disease is a X-linked recessively inherited metabolic disorder, which results from the deficient activity of the lysosomal hydrolase alpha-galactosidase A leading to the systemic deposition of glycosphingolipids with terminal alpha-galactosyl moieties. Single-strand conformation polymorphism (SSCP) analysis was performed, followed by DNA sequencing of PCR amplified exons of the human alpha-galactosidase A gene in 5 unrelated Korean patients with classic Fabry disease. Five different mutations were identified; two nonsense mutations (Y86X and R342X), one missense mutation (D266N), and two small deletions (296del2 and 802del4). Except for R342X mutation, four were novel mutations (Y86X, D266N, 296del2, 802del4). A T to G transversion at nucleotide position 5157 in exon 2 caused a tyrosine-to-stop substitution at codon 86. A G to A transition at position 10287 in exon 5 substituted an asparagine for an aspartate at codon 266. Mutation 296del2 in exon 2 resulted in a frame shift with a stop signal at the 22th codon downstream from the mutation, whereas mutation 802del4 resulted in a stop codon at the site of 4 bp deletion. In addition, the 802del4 was found to be a de novo mutation. This is the first report on mutation analysis of the human alpha-galactosidase A gene in Korean patients with Fabry disease.

Biopsy-proven cardiomyopathy in heterozygous Fabry's disease

A 23-year-old woman with heterozygous Fabry's disease who had acroparesthesia was admitted to hospital for precise examination of the disease before childbearing. She had no cardiac-related symptoms and no abnormality on physical examination. The alpha-galactosidase A activity in her leukocytes was present, but lower than normal. However, the endomyocardial biopsy showed specific changes for Fabry's disease. As Fabry's disease is a rare X-linked recessive inborn error of glycosphingolipid metabolism, heterozygous females are usually asymptomatic, but rarely can be affected as severely as hemizygous males. This is an isolated case of heterozygous Fabry's disease in a female in whom cardiac involvement was detected by endomyocardial biopsy, although she had no cardiac abnormality on physiological examinations. In conclusion, endomyocardial biopsy is useful for evaluation of the cardiac involvement of Fabry's disease even in an asymptomatic case.

Vasospastic angina in a patient with Fabry's disease who showed normal coronary angiographic findings

It has been reported that coronary diseases in patients with Fabry's disease are induced by deposits in endothelial cells and coronary smooth muscle cells. Most of those are ischemia due to stenosis. This report describes a case of patient with Fabry's disease who showed severe vasospasms without coronary artery stenosis during acetylcholine loaded coronary angiography. In this case, a myocardial biopsy revealed that the deposits in the endothelial cells of the myocardial capillaries were lamellated appearance. Recently, it is reported that endothelial cell damage could be an important cause of coronary vasospasm. This case suggests that the some sort of functional disorder was induced by glyco-sphingolipid deposits in the coronary endothelial cells, and that this might have led to coronary artery spasms without the organic stenosis of coronary arteries.

An atypical variant of Fabry's disease in men with left ventricular hypertrophy

BACKGROUND

Fabry's disease is considered very rare. Left ventricular hypertrophy is one of the common manifestations in adults with classic hemizygous disease. Recently, several cases of an atypical variant of hemizygous Fabry's disease, with manifestations limited to the heart, have been reported. Therefore, we assessed the incidence of hemizygosity for Fabry's disease among male patients with left ventricular hypertrophy.

METHODS

We measured plasma alpha-galactosidase activity in 230 consecutive male patients with left ventricular hypertrophy. Clinical manifestations were assessed, endomyocardial biopsies were performed, and the patients were screened for mutations in the alpha-galactosidase gene.

RESULTS

Seven of the 230 patients with left ventricular hypertrophy (3 percent) had low plasma alpha-galactosidase activity (0.4 to 1.2 nmol per hour per milliliter; 4 to 14 percent of the mean value in normal controls). These seven unrelated patients, ranging in age from 55 to 72 years, did not have angiokeratoma, acroparesthesias, hypohidrosis, or corneal opacities, which are typical manifestations of Fabry's disease. Endomyocardial biopsy was performed in five patients and revealed marked sarcoplasmic vacuolization in all five. Samples from four patients were examined by electron microscopy and revealed typical lysosomal inclusions with a concentric lamellar configuration in all four. Two patients had novel missense mutations in exon 1 (Ala20Pro) and exon 6 (Met296lle). The remaining five had no mutations in the coding region of the alpha-galactosidase gene, but the amounts of the alpha-galactosidase messenger RNA were markedly lower than normal.

CONCLUSIONS

Seven unrelated patients with atypical variants of hemizygous Fabry's disease were found among 230 men with left ventricular hypertrophy (3 percent). Fabry's disease should be considered as a cause of unexplained left ventricular hypertrophy.

Restricted accumulation of globotriaosylceramide in the hearts of atypical cases of Fabry's disease

Immunohistochemical and biochemical analyses of several tissues were performed in two unusual cases of Fabry's disease which showed accumulation of globotriaosylceramide (Gal alpha 1-4Gal beta 1-4 Glc-Cer, Gb3Cer) only in the hearts, but no clinical signs of the disease. Immunohistochemical study revealed that the hearts from our cases (cases no. 1 and 2) contained large amounts of anti-Gb3Cer antibody-positive granules in cytoplasms as in typical Fabry's disease. The contents of accumulated Gb3Cer in the hearts from case no. 1, case no. 2, and a typical Fabry's disease case were approximately 100, 340, and 100 times higher than those from normal controls, respectively. While typical Fabry's diseased kidney and liver contained approximately 40 and 50 times higher amounts of Gb3Cer than did controls, no accumulation of Gb3Cer was observed in kidney and liver of our cases. The only exception was a slight increase of Gb3Cer in kidney of case no. 2 (about two times higher than controls), in which epithelial cells of the glomeruli but not of other types of cells were positively stained by anti-Gb3Cer antibody. Case no. 1 kidney and liver were not stained by the antibody. The glomerular endothelium and epithelium, tubular epithelium, smooth muscle of renal arteries, and several hepatocytes were Gb3Cer-positive in the typical Fabry's disease case. The involvements of our cases differed distinctly from the typical Fabry's disease case.

Accumulation of glycosphingolipids in spinal and sympathetic ganglia of a symptomatic heterozygote of Fabry's disease

Fabry's disease is an X-linked disorder of glycolipid catabolism. We have found a symptomatic heterozygous female with cardiomyopathy and severe pain in the extremities. We studied histochemically and biochemically the accumulated glycolipids in spinal and sympathetic ganglia of the patient. Histochemical examination demonstrated the marked glycolipid deposits that have been observed in heterozygous males in these ganglia. Gas-liquid chromatography (GLC) revealed that these accumulated glycolipids were characterized as globotriaosylceramide (Gb3cer) and galabiosylceramide (Ga2cer). In the heterozygous female, the accumulations of Gb3cer in spinal and sympathetic ganglia were, respectively, 34 and 48 times the amount in normal controls. This is the first report on quantitative and qualitative analyses of the accumulated glycolipids in spinal and sympathetic ganglia of a heterozygous carrier female.

Echocardiographic abnormalities and disease severity in Fabry's disease

Fabry's disease is an X-linked recessive genetic deficiency of the enzyme alpha-galactosidase A, which leads to the pathologic deposition of neutral glycosphingolipids in lysosomes of the vascular endothelium of the heart, brain and kidney. The disease is progressive in hemizygous male patients, with increasing involvement of the major organs leading to death. Because cardiac involvement is a constant feature, echocardiograms were performed on 35 patients with Fabry's disease, 23 hemizygotes (aged 28.6 +/- 14 years) and 12 heterozygotes (aged 31.6 +/- 6 years), to determine whether cardiac involvement could be detected noninvasively. The results demonstrated that hemizygous male patients had a greater aortic root diameter, thicker interventricular septum and greater ventricular mass than did heterozygous female patients. Left ventricular mass per square meter of body surface area correlated well with clinical disease severity (r = 0.68, p less than 0.05), suggesting progressive glycosphingolipid deposition. Older heterozygotes (greater than 25 years old) had more severe evidence of cardiac disease than did younger male patients. Although mitral valve prolapse was identified in 12 (54%) of 23 male hemizygotes and in 7 (58%) of 12 female heterozygotes its presence did not correlate with clinical disease severity or other echocardiographic variables. Therefore, echocardiographic evidence of Fabry's disease appears to correlate with age-related disease severity and may be a useful noninvasive marker to follow disease progression and possible regression when appropriate therapy becomes available.

Two dimensional echocardiographic similarity of Fabry's disease to cardiac amyloidosis: a function of ultrastructural analogy?

A 53-year-old man with Fabry's disease was studied by echocardiography. Both M-mode and two dimensional echocardiographic examinations produced findings indistinguishable from those previously described as virtually diagnostic of cardiac amyloidosis. Possible causes for the "granular sparkling" appearance and clinical implications of the similarities were discussed.

Testicular and epididymal involvement in Fabry's disease

Autopsy specimens of the testes and epididymis of a 32-year-old male with Fabry's disease were studied by light and electron microscopy. The characteristic ceramide deposits (lamellar inclusions, myeloid-bodies, zebra-bodies) were found in the Leydig cells as well as in the epithelial lining of both the ductuli efferentes and the ductus of the epididymis. Similar myeloid-bodies were observed in the blood vessels, connective tissue cells and muscle cells of the testicular interstitium, tunica albuginea and epididymis. In contrast, myeloid-bodies were absent or scarce in both the seminiferous epithelium and the mediastinum testis. However, the seminiferous tubules were severely affected showing reduced diameter, thickening of the tunica propria, and a few degenerated spermatogonia and primary spermatocytes. The different degrees of involvement of the testicular structures might be related to their different functions, the absorptive and permeable structures being the most severely affected. The development of testicular alterations seems to have been slow, since the patient fathered three children.

Peripheral hemodynamics in patients with Fabry's disease

Altered vasomotor activity has been reported as a clinically prominent feature of Fabry's disease (angiokeratoma corporis diffusum universale). While symptomatic cardiovascular involvement occurs eventually in most patients with this disorder, little is known concerning the effect of Fabry's disease on peripheral hemodynamics. Peripheral hemodynamics in the extremities and digits were studied in eight patients with Fabry's disease by means of segmental and venous occlusion pneumoplethysmography and thermal probes, and the results obtained were compared with those of 10 normal subjects. Forearm vascular resistance in Fabry's disease patients was significantly higher (p less than 0.01) than that in normal subjects. Forearm venous capacitance in Fabry's disease was significantly lower (p less than 0.01). Segmental pulse volume amplitudes showed no significant difference in any segments (upper arm, wrist, thigh, above and below knee, and the calf) between the two groups. Finger and toe blood flow, finger and toe pulse volume, and temperature in the resting state were all significantly less (p less than 0.01, p less than 0.05: p less than 0.01, p less than 0.01: p less than 0.05, p less than 0.05, respectively) than those in normal subjects. Finger and toe blood flow and pulse volume after vasodilation procedures were significantly less (p less than 0.05, p less than 0.01: p less than 0.05, p less than 0.01, respectively) than those in normal subjects despite equal elevation of digital temperature obtained after vasodilation in both groups. These findings indicate the presence of vasoconstrictive process in both resistance vessels and capacitances vessels in cutaneous and skeletal muscular beds. A limited response in the cutaneous circulation to vasodilation procedures also was seen. These data suggest the possibility that latent enhanced sympathoadrenal discharge as well as the accumulation of glycolipid in the autonomic nervous system and vessel walls plays an important role in the disturbed pathophysiology of this disorder.

Cholesteryl ester crystals in a porcine aortic valvular bioprosthesis implanted for eight years

Masses of crystals, which were largely composed of cholesteryl esters, were found in a porcine aortic valvular bioprosthesis removed eight years after implantation in the mitral position in a patient with rheumatic mitral valvular stenosis. Histologic sections of grossly raised and nonraised yellow lesions in the three cusps of this bioprosthesis revealed large clefts, which on frozen section contained lipid-positive, birefringent crystals. These crystals gave a positive reaction with the Schultz test for cholesterol. Biochemical analyses of isolated nodules revealed a cholesterol content of 40 nmole/mg of wet tissue. Of this cholesterol, 88 percent was esterified, and the remaining 12 percent was free cholesterol. These cholesterol deposits are most likely derived from blood lipids; however, they were not related to hyperlipidemia, since the patient had normal blood levels of cholesterol and triglycerides.