Fabry disease Schwann cells release p11 to induce sensory neuron hyperactivity.

Patients with Fabry disease suffer from chronic debilitating pain and peripheral sensory neuropathy with minimal treatment options, but the cellular drivers of this pain are unknown. Here, we propose a mechanism we believe to be novel in which altered signaling between Schwann cells and sensory neurons underlies the peripheral sensory nerve dysfunction we observed in a genetic rat model of Fabry disease. Using in vivo and in vitro electrophysiological recordings, we demonstrated that Fabry rat sensory neurons exhibited pronounced hyperexcitability. Schwann cells probably contributed to this finding because application of mediators released from cultured Fabry Schwann cells induced spontaneous activity and hyperexcitability in naive sensory neurons. We examined putative algogenic mediators using proteomic analysis and found that Fabry Schwann cells released elevated levels of the protein p11 (S100A10), which induced sensory neuron hyperexcitability. Removal of p11 from Fabry Schwann cell media caused hyperpolarization of neuronal resting membrane potentials, indicating that p11 may contribute to the excessive neuronal excitability caused by Fabry Schwann cells. These findings demonstrate that sensory neurons from rats with Fabry disease exhibit hyperactivity caused in part by Schwann cell release of the protein p11.

Incidence and risk factors for development of left ventricular hypertrophy in Fabry disease.

BACKGROUND: Left ventricular hypertrophy (LVH) is the principal cardiac manifestation of Fabry disease (FD). This study aimed to determine the incidence and predictors of LVH development in a contemporary cohort of patients with FD and no LVH at baseline evaluation. METHODS: Consecutively referred adult (aged ≥16 years) patients with FD were enrolled into an observational cohort study. Patients were prospectively followed in a specialist cardiomyopathy centre and the primary endpoint was the first detection of LVH (left ventricular mass index (LVMi) ≥115 g/m2 in men and ≥95 g/m2 in women). RESULTS: From a cohort of 393 patients, 214 (aged 35.8±13.8 years; 61 (29%) males) had no LVH at first evaluation. During a median follow-up of 9.4 years (IQR 4.7-12.7), 55 patients (24.6%) developed LVH. The estimated incidence of LVH was 11.3% (95% CI 6.5% to 16.1%) at 5 years, 29.1% (95% CI 21.5% to 36.7%) at 10 years and 45.0% (95% CI 33.8% to 62.4%) at 15 years of follow-up. On multivariable analysis, independent predictors for LVH development were age (HR 1.04 (95% CI 1.02 to 1.06) per 1-year increase, p<0.001), male sex (HR 2.90 (95% CI 1.66 to 5.09), p<0.001) and an abnormal ECG (HR 3.10 (95% CI 1.72 to 5.57), p<0.001). The annual rate of change in LVMi was +2.77 (IQR 1.45-4.62) g/m2/year in males and +1.38 (IQR 0.09-2.85) g/m2/year in females (p<0.001). CONCLUSIONS: Approximately one-quarter of patients with FD developed LVH during follow-up. Age, male sex and ECG abnormalities were associated with a higher risk of developing LVH in patients with FD.

A Case of a 49-Year-Old Man with Nonclassical Fabry Disease Diagnosed by Renal Biopsy.

Fabry disease (FD) is a rare X-linked lysosomal storage disorder caused by mutations in the galactosidase A (GLA) gene that result in deficiency of α-GLA activity, leading to major organ failure and premature mortality. According to different disease courses, FD can be divided into classical and nonclassical phenotypes. The nonclassical FD phenotype is always absent of characteristic symptoms, which makes identifying it challenging. This article presents a 49-year-old man with a 10-year history of proteinuria and decreased glomerular filtration rate. An electrocardiogram showed a complete right bundle branch block and abnormal Q waves in high lateral, accompanied by dramatically elevated ST segment. Consequently, a renal biopsy was performed. Vacuolation was found in many podocytes in light microscopic examinations. Similarly, a myelin-like structure was detected by electron microscopy. Pathological findings were most consistent with FD. Consequently, genetic analysis, p.R301Q (c.902G>A [p.Arg301Gln]), confirmed the FD diagnosis. Angiotensin receptor blocker and traditional Chinese medicine, but not enzyme replacement therapy, were prescribed due to financial constraints. The patient had stabilization of kidney disease 6 months later. The case showed that renal biopsy should be performed in patients with cardiac and renal symptoms, which could contribute toward the correct diagnosis for nonclassical FD type.

Endothelial Dysfunction in Fabry Disease Is Related to Glycocalyx Degradation.

Fabry disease (FD) is an X-linked multisystemic lysosomal storage disease due to a deficiency of α-galactosidase A (GLA/AGAL). Progressive cellular accumulation of the AGAL substrate globotriaosylceramide (Gb3) leads to endothelial dysfunction. Here, we analyzed endothelial function in vivo and in vitro in an AGAL-deficient genetic background to identify the processes underlying this small vessel disease. Arterial stiffness and endothelial function was prospectively measured in five males carrying GLA variants (control) and 22 FD patients under therapy. AGAL-deficient endothelial cells (EA.hy926) and monocytes (THP1) were used to analyze endothelial glycocalyx structure, function, and underlying inflammatory signals. Glycocalyx thickness and small vessel function improved significantly over time (p<0.05) in patients treated with enzyme replacement therapy (ERT, n=16) and chaperones (n=6). AGAL-deficient endothelial cells showed reduced glycocalyx and increased monocyte adhesion (p<0.05). In addition, increased expression of angiopoietin-2, heparanase and NF-κB was detected (all p<0.05). Incubation of wild-type endothelial cells with pathological globotriaosylsphingosine concentrations resulted in comparable findings. Treatment of AGAL-deficient cells with recombinant AGAL (p<0.01), heparin (p<0.01), anti-inflammatory (p<0.001) and antioxidant drugs (p<0.05), and a specific inhibitor (razuprotafib) of angiopoietin-1 receptor (Tie2) (p<0.05) improved glycocalyx structure and endothelial function in vitro. We conclude that chronic inflammation, including the release of heparanases, appears to be responsible for the degradation of the endothelial glycocalyx and may explain the endothelial dysfunction in FD. This process is partially reversible by FD-specific and anti-inflammatory treatment, such as targeted protective Tie2 treatment.

Mechanisms of Neutralizing Anti-drug Antibody Formation and Clinical Relevance on Therapeutic Efficacy of Enzyme Replacement Therapies in Fabry Disease.

Fabry disease (FD) is a rare X-linked lysosomal storage disorder caused by mutations in the α-galactosidase A (AGAL/GLA) gene. The lysosomal accumulation of the substrates globotriaosylceramide (Gb3) and globotriaosylsphingosine (lyso-Gb3) results in progressive renal failure, cardiomyopathy associated with cardiac arrhythmia, and recurrent strokes, significantly limiting life expectancy in affected patients. Current treatment options for FD include recombinant enzyme-replacement therapies (ERTs) with intravenous agalsidase-α (0.2 mg/kg body weight) or agalsidase-ß (1 mg/kg body weight) every 2 weeks, facilitating cellular Gb3 clearance and an overall improvement of disease burden. However, ERT can lead to infusion-associated reactions, as well as the formation of neutralizing anti-drug antibodies (ADAs) in ERT-treated males, leading to an attenuation of therapy efficacy and thus disease progression. In this narrative review, we provide a brief overview of the clinical picture of FD and diagnostic confirmation. The focus is on the biochemical and clinical significance of neutralizing ADAs as a humoral response to ERT. In addition, we provide an overview of different methods for ADA measurement and characterization, as well as potential therapeutic approaches to prevent or eliminate ADAs in affected patients, which is representative for other ERT-treated lysosomal storage diseases.

Pathogenesis and Molecular Mechanisms of Anderson-Fabry Disease and Possible New Molecular Addressed Therapeutic Strategies.

Anderson-Fabry disease (AFD) is a rare disease with an incidenceof approximately 1:117,000 male births. Lysosomal accumulation of globotriaosylceramide (Gb3) is the element characterizing Fabry disease due to a hereditary deficiency α-galactosidase A (GLA) enzyme. The accumulation of Gb3 causes lysosomal dysfunction that compromises cell signaling pathways. Deposition of sphingolipids occurs in the autonomic nervous system, dorsal root ganglia, kidney epithelial cells, vascular system cells, and myocardial cells, resulting in organ failure. This manuscript will review the molecular pathogenetic pathways involved in Anderson-Fabry disease and in its organ damage. Some studies reported that inhibition of mitochondrial function and energy metabolism plays a significant role in AFD cardiomyopathy and in kidney disease of AFD patients. Furthermore, mitochondrial dysfunction has been reported as linked to the dysregulation of the autophagy-lysosomal pathway which inhibits the mechanistic target of rapamycin kinase (mTOR) mediated control of mitochondrial metabolism in AFD cells. Cerebrovascular complications due to AFD are caused by cerebral micro vessel stenosis. These are caused by wall thickening resulting from the intramural accumulation of glycolipids, luminal occlusion or thrombosis. Other pathogenetic mechanisms involved in organ damage linked to Gb3 accumulation are endocytosis and lysosomal degradation of endothelial calcium-activated intermediate-conductance potassium ion channel 3.1 (KCa3.1) via a clathrin-dependent process. This process represents a crucial event in endothelial dysfunction. Several studies have identified the deacylated form of Gb3, globotriaosylsphingosine (Lyso-Gb3), as the main catabolite that increases in plasma and urine in patients with AFD. The mean concentrations of Gb3 in all organs and plasma of Galactosidase A knockout mice were significantly higher than those of wild-type mice. The distributions of Gb3 isoforms vary from organ to organ. Various Gb3 isoforms were observed mainly in the kidneys, and kidney-specific Gb3 isoforms were hydroxylated. Furthermore, the action of Gb3 on the KCa3.1 channel suggests a possible contribution of this interaction to the Fabry disease process, as this channel is expressed in various cells, including endothelial cells, fibroblasts, smooth muscle cells in proliferation, microglia, and lymphocytes. These molecular pathways could be considered a potential therapeutic target to correct the enzyme in addition to the traditional enzyme replacement therapies (ERT) or drug chaperone therapy.

Prompt Agalsidase Alfa Therapy Initiation is Associated with Improved Renal and Cardiovascular Outcomes in a Fabry Outcome Survey Analysis.

BACKGROUND: The timing of enzyme replacement therapy initiation in patients with Fabry disease is hypothesized to be critical. In this study, we used Fabry Outcome Survey data to assess the impact of prompt versus delayed initiation of treatment with agalsidase alfa on cardiovascular and renal events in patients with Fabry disease. METHODS: Available genetic data at baseline were used to define patients with mutations associated with classical versus late-onset Fabry disease. Time to cardiovascular or renal events, from treatment initiation until 120 months, was compared for patients in prompt versus delayed groups. "Prompt" was defined as treatment initiation <24 months from symptom onset (analysis A) or diagnosis (analysis B), and "delayed" was defined as ≥24 months from symptom onset (analysis A) or diagnosis (analysis B). Kaplan-Meier curves and Log rank tests compared event-free probabilities and time to first event. Multivariate Cox regression estimated hazard ratios (HRs). RESULTS: Analysis by time from symptom onset included 1374 patients (172 prompt, 1202 delayed). In a multivariate Cox regression analysis, prompt versus delayed treatment initiation significantly reduced the probability of cardiovascular (HR=0.62; P<0.001) and renal (HR=0.57; P=0.001) events. History of cardiovascular or renal events was associated with increased risk of respective events. Analysis by time from diagnosis included 2051 patients (1006 prompt, 1045 delayed). In a multivariate Cox regression analysis, prompt treatment initiation significantly reduced the probability of cardiovascular events (HR=0.83; P=0.003) after adjusting for history of cardiovascular events, sex, and age at treatment initiation. Univariate analysis showed that the probability of renal events was significantly lower in the prompt group (P=0.018); this finding was attenuated in the multivariate Cox regression analysis. CONCLUSION: This analysis suggests that prompt treatment initiation with agalsidase alfa provided better renal and cardiovascular outcomes than delayed treatment in patients with Fabry disease.

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.

Elevated Ambulatory Blood Pressure Measurements are Associated with a Progressive Form of Fabry Disease.

 INTRODUCTION: Published data on hypertension incidence and management in Anderson-Fabry disease are scant and the contribution of elevated blood pressure to organ damage is not well recognized. AIM: Therefore, we have assessed blood pressure values and their possible correlations with clinical findings in a well described cohort of Fabry patients. METHODS: Between January 2015 and May 2019, all adult Fabry patients (n = 24 females, n = 8 males) referred to our institute were prospectively enrolled. During the first examination patient's genotype and clinical characteristics were recorded. Blood pressure data were obtained by standard observed office measurements followed, within 6 months, by ambulatory blood pressure monitoring and home self-recordings. Organ involvement, including kidneys, heart and brain, was monitored over time. Consequently, patients were defined as clinically stable or progressive through the Fabry Stabilization Index. RESULTS: The standard office measurements have diagnosed hypertension in three (9.37%) patients, but the ambulatory monitoring showed elevated blood pressure in six (18.75%) patients, revealing three cases of masked hypertension. All the hypertensive patients were females and, compared with normotensive subjects, they presented a lower glomerular filtration rate (p < 0.05) and a more advanced cardiac hypertrophy (p < 0.05). Four (66.7%) of them were diagnosed with a progressive form of the disease through the Fabry Stabilization Index while the majority of the normotensive group (84.6%, n = 19) was stable over time. No correlation was found between the prevalence of hypertension and the type of mutations causing Fabry disease. CONCLUSION: Hypertension can be found in a restricted portion of clinically stable Fabry patients. In contrast, patients presenting with a progressive organ involvement, particularly renal impairment, have a major risk of developing uncontrolled blood pressure, and should be followed carefully. Moreover, the ambulatory blood pressure monitoring proved to be useful to reveal masked hypertension, which can contribute to the progressive worsening of the organ damage. Therefore, a proper diagnosis and therapy of hypertension may improve the outcome of Fabry patients.

Fabry Disease: Molecular Basis, Pathophysiology, Diagnostics and Potential Therapeutic Directions.

Fabry disease (FD) is a lysosomal storage disorder (LSD) characterized by the deficiency of α-galactosidase A (α-GalA) and the consequent accumulation of toxic metabolites such as globotriaosylceramide (Gb3) and globotriaosylsphingosine (lysoGb3). Early diagnosis and appropriate timely treatment of FD patients are crucial to prevent tissue damage and organ failure which no treatment can reverse. LSDs might profit from four main therapeutic strategies, but hitherto there is no cure. Among the therapeutic possibilities are intravenous administered enzyme replacement therapy (ERT), oral pharmacological chaperone therapy (PCT) or enzyme stabilizers, substrate reduction therapy (SRT) and the more recent gene/RNA therapy. Unfortunately, FD patients can only benefit from ERT and, since 2016, PCT, both always combined with supportive adjunctive and preventive therapies to clinically manage FD-related chronic renal, cardiac and neurological complications. Gene therapy for FD is currently studied and further strategies such as substrate reduction therapy (SRT) and novel PCTs are under investigation. In this review, we discuss the molecular basis of FD, the pathophysiology and diagnostic procedures, together with the current treatments and potential therapeutic avenues that FD patients could benefit from in the future.

Influence of sex and phenotype on cardiac outcomes in patients with Fabry disease.

OBJECTIVE: This study describes the influence of sex and disease phenotype on the occurrence of cardiac events in Fabry disease (FD). METHODS: Cardiac events from birth to last visit (median age 50 years) were recorded for 213 patients with FD. Patients were categorised as follows : men with classical FD (n=57), men with non-classical FD (n=26), women with classical FD (n=98) and women with non-classical FD (n=32), based on the presence of classical FD symptoms, family history (men and women), biomarkers and residual enzyme activity (men). Event rates per 1000 patient-years after the age of 15 years and median event-free survival (EVS) age were presented. Influence of disease phenotype, sex and their interaction was studied using Firth's penalised Cox regression. RESULTS: The event rates of major cardiovascular events (combined endpoint cardiovascular death (CVD), heart failure (HF) hospitalisation, sustained ventricular arrhythmias (SVAs) and myocardial infarction) were 11.0 (95% CI 6.6 to 17.3) in men with classical FD (EVS 55 years), 4.4 (95% CI 2.5 to 7.1) in women with classical FD (EVS 70 years) and 5.9 (95% CI 2.6 to 11.6) in men with non-classical FD (EVS 70 years). None of these events occurred in women with non-classical FD. Sex and phenotype significantly influenced the risk of major adverse cardiovascular event. CVD was the leading cause of death (75%) to which HF contributed most (42%). The overall rate of SVA was low (14 events in nine patients (4%)). CONCLUSIONS: Sex and phenotype greatly influence the risk and age of onset of cardiac events in FD. This indicates the need for patient group-specific follow-up and treatment.

Focal reduction in left ventricular 123I-metaiodobenzylguanidine uptake and impairment in systolic function in patients with Anderson-Fabry disease.

BACKGROUND: Abnormalities of cardiac sympathetic innervation have been demonstrated in Anderson-Fabry disease (AFD). We aimed to investigate the relationship between regional left ventricular (LV) denervation and regional function abnormalities. METHODS: Twenty-four AFD patients (43.7 ± 12.8 years) were studied by 123I-metaiodobenzylguanidine (MIBG) cardiac imaging and speckle-tracking echocardiography. Segmental tracer uptake was estimated according to 0 to 4 score, and total defect score (TDS) was calculated for each patient. RESULTS: Segmental longitudinal strain worsened as MIBG uptake score increased (P < 0.001). By ROC analysis, a segmental longitudinal strain > - 16.2% predicted a segmental MIBG uptake score ≥1, with 79.7% sensitivity and 65.3% specificity. Segmental MIBG uptake defects were found in 13 out 24 AFD patients. LV mass index (60.8 ± 10.1 vs. 41.4 ± 9.8 g/h2.7), relative wall thickness (0.51 ± 0.06 vs. 0.40 ± 0.06), systolic pulmonary artery pressure (35.2 ± 6.7 vs. 27.2 ± 4.2 mmHg), and longitudinal strain (- 14.3 ± 2.7 vs. -19.4 ± 1.8%) were significantly higher in patients with segmental defect (all P < 0.01). At multivariate linear regression analysis, global longitudinal strain was independently associated with TDS (B = 3.007, 95% confidence interval 1.384 to 4.630, P = 0.001). CONCLUSIONS: Reduced cardiac MIBG uptake reflects the severity of cardiac involvement in AFD patients. LV longitudinal function impairment seems to be an earlier disease feature than regional myocardial denervation.

Effects of Baseline Left Ventricular Hypertrophy and Decreased Renal Function on Cardiovascular and Renal Outcomes in Patients with Fabry Disease Treated with Agalsidase Alfa: A Fabry Outcome Survey Study.

PURPOSE: The initiation of enzyme-replacement therapy prior to the occurrence of substantial and irreversible organ damage in patients with Fabry disease is of critical importance. The Fabry Outcome Survey is an international disease registry of patients with a confirmed diagnosis of Fabry disease. In this study, data from the Fabry Outcome Survey were used for the assessment of the risks for cardiovascular and renal events in patients who received agalsidase alfa treatment. METHODS: Eligible patients were males and females aged ≥18 years with Fabry disease treated with agalsidase alfa. Cardiovascular events included myocardial infarction, left ventricular hypertrophy (LVH), heart failure, arrhythmia, conduction abnormality, and cardiac surgery. Renal events included dialysis, transplantation, and renal failure. Kaplan-Meier curves and log-rank tests were used for comparing event-free probabilities and time to first cardiovascular or renal event, from agalsidase alfa initiation to a maximum of 120 months, in patients with LVH versus normal left ventricular mass index (LVMI; ≤50 g/m2.7 in males and ≤48 g/m2.7 in females) at treatment initiation (baseline), and in patients with a low estimated glomerular filtration rate (eGFR; <90 mL/min/1.73 m2) versus normal eGFR at baseline. Multivariate Cox regression analysis was used for examining the association between key study variables and the risks for cardiovascular and renal events. FINDINGS: Among the 560 patients (269 males; 291 females) with available LVMI data, 306 (55%) had LVH and 254 (45%) had normal LVMI at baseline. The risk for a cardiovascular event was higher in the subgroup with LVH versus normal LVMI at baseline (hazard ratio [HR] = 1.57; 95% CI, 1.21-2.05; P < 0.001), but the risk for a renal event was similar between the 2 subgroups (HR = 1.90; 95% CI, 0.94-3.85; P = 0.074). Among the 1093 patients (551 males; 542 females) with available eGFR data, 433 (40%) had a low eGFR and 660 (60%) had a normal eGFR at baseline. The subgroup with a low eGFR at baseline had a significantly higher risk for a cardiovascular event (HR = 1.33; 95% CI, 1.04-1.70; P = 0.021) or a renal event (HR = 5.88; 95% CI, 2.73-12.68; P < 0.001) compared with patients with a normal eGFR at baseline. IMPLICATIONS: In the present study, the presence of LVH and/or reduced renal function at agalsidase alfa initiation was associated with a significantly higher risk for a cardiovascular or renal event, indicating that cardiovascular and renal pathologies in Fabry disease may be inter-related. Early initiation of agalsidase alfa treatment prior to the onset of severe organ damage may improve outcomes. ClinicalTrials.gov identifier: NCT03289065.

Therapeutic advances in Fabry disease: The future awaits.

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

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

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

The value of electrocardiography and echocardiography in distinguishing Fabry disease from sarcomeric hypertrophic cardiomyopathy.

BACKGROUND: Screening for Fabry disease is sub-optimal in non-specialised centres. AIM: To assess the diagnostic value of electrocardiographic scores of left ventricular hypertrophy and a combined electrocardiographic and echocardiographic model in Fabry disease. METHODS: We retrospectively reviewed the electrocardiograms and echocardiograms of 61 patients (mean age 55.6±11.5 years; 57% men) with Fabry disease and left ventricular hypertrophy, and compared them with those from 59 patients (mean age 44.8±18.3 years; 66% men) with sarcomeric hypertrophic cardiomyopathy. Six electrocardiography criteria for left ventricular hypertrophy were specifically analysed: Sokolow-Lyon voltage index; Cornell voltage index; Gubner index; Romhilt-Estes score; Sokolow-Lyon product (voltage index×QRS duration); and Cornell product (voltage index×QRS duration). RESULTS: Right bundle branch block was more frequent in patients with Fabry disease (54% vs. 22%; P=0.001). QRS duration, Gubner score and Sokolow-Lyon product were significantly higher in patients with Fabry disease. Maximal wall thickness was higher in patients with sarcomeric hypertrophic cardiomyopathy (21.9±5.1 vs. 15.5±2.9mm; P<0.001). Indexed sinus of Valsalva diameter was larger in patients with Fabry disease. After multivariable analysis, right bundle branch block, Sokolow-Lyon product, maximal wall thickness and aortic diameter were independently associated with Fabry disease. A model including these four variables yielded an area under the receiver operating characteristic curve of 0.918 (95% confidence interval 0.868-0.968) for Fabry disease. CONCLUSION: Our model combining easy-to-assess electrocardiographic and echocardiographic variables may be helpful in improving screening and reducing diagnosis delay in Fabry disease.

When and How to Diagnose Fabry Disease in Clinical Pratice.

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

Clinical evaluation of infiltrative cardiomyopathies resulting in heart failure with preserved ejection fraction.

Heart failure with preserved ejection fraction is a very common clinical problem. Its prevalence is increasing with aging of the population. A diverse group of risk factors and etiologies comprise the HFpEF syndrome. No specific therapies have been shown to improve survival for the vast majority of HFpEF cases. Restrictive cardiomyopathies account for a significant portion of HFpEF patients and are characterized by diastolic dysfunction due to infiltration of the myocardium or ventricular hypertrophy. Many of these restrictive diseases occur in the context of myocardial infiltration by other substances such as amyloid, iron or glycogen or endomyocardial fibrosis. These infiltrative diseases usually have important clues in the clinical picture and on cardiac imaging that may allow differentiation from the usual HFpEF phenotype (that is commonly seen in the older, hypertensive patient). Noninvasive diagnosis has replaced endomyocardial biopsy for most instances in the workup of these conditions. Early recognition is important to institute specific therapies and to improve prognosis. In this review, we describe 4 major infiltrative cardiomyopathies (Cardiac Amyloidosis, Sarcoidosis, Hemochromatosis and Fabry disease), and their key imaging features.