Head-to-head trial of pegunigalsidase alfa versus agalsidase beta in patients with Fabry disease and deteriorating renal function: results from the 2-year randomised phase III BALANCE study

BACKGROUND

Pegunigalsidase alfa is a PEGylated α-galactosidase A enzyme replacement therapy. BALANCE (NCT02795676) assessed non-inferiority of pegunigalsidase alfa versus agalsidase beta in adults with Fabry disease with an annualised estimated glomerular filtration rate (eGFR) slope more negative than -2 mL/min/1.73 m2/year who had received agalsidase beta for ≥1 year.

METHODS

Patients were randomly assigned 2:1 to receive 1 mg/kg pegunigalsidase alfa or agalsidase beta every 2 weeks for 2 years. The primary efficacy analysis assessed non-inferiority based on median annualised eGFR slope differences between treatment arms.

RESULTS

Seventy-seven patients received either pegunigalsidase alfa (n=52) or agalsidase beta (n=25). At baseline, mean (range) age was 44 (18-60) years, 47 (61%) patients were male, median eGFR was 74.5 mL/min/1.73 m2 and median (range) eGFR slope was -7.3 (-30.5, 6.3) mL/min/1.73 m2/year. At 2 years, the difference between median eGFR slopes was -0.36 mL/min/1.73 m2/year, meeting the prespecified non-inferiority margin. Minimal changes were observed in lyso-Gb3 concentrations in both treatment arms at 2 years. Proportions of patients experiencing treatment-related adverse events and mild or moderate infusion-related reactions were similar in both groups, yet exposure-adjusted rates were 3.6-fold and 7.8-fold higher, respectively, with agalsidase beta than pegunigalsidase alfa. At the end of the study, neutralising antibodies were detected in 7 out of 47 (15%) pegunigalsidase alfa-treated patients and 6 out of 23 (26%) agalsidase beta-treated patients. There were no deaths.

CONCLUSIONS

Based on rate of eGFR decline over 2 years, pegunigalsidase alfa was non-inferior to agalsidase beta. Pegunigalsidase alfa had lower rates of treatment-emergent adverse events and mild or moderate infusion-related reactions.

TRIAL REGISTRATION NUMBER

NCT02795676.

In vivo demonstration of globotriaosylceramide brain accumulation in Fabry Disease using MR Relaxometry

PURPOSE

How to measure brain globotriaosylceramide (Gb3) accumulation in Fabry Disease (FD) patients in-vivo is still an open challenge. The objective of this study is to provide a quantitative, non-invasive demonstration of this phenomenon using quantitative MRI (qMRI).

METHODS

In this retrospective, monocentric cross-sectional study conducted from November 2015 to July 2018, FD patients and healthy controls (HC) underwent an MRI scan with a relaxometry protocol to compute longitudinal relaxation rate (R1) maps to evaluate gray (GM) and white matter (WM) lipid accumulation. In a subgroup of 22 FD patients, clinical (FAbry STabilization indEX -FASTEX- score) and biochemical (residual α-galactosidase activity) variables were correlated with MRI data. Quantitative maps were analyzed at both global ("bulk" analysis) and regional ("voxel-wise" analysis) levels.

RESULTS

Data were obtained from 42 FD patients (mean age = 42.4 ± 12.9, M/F = 16/26) and 49 HC (mean age = 42.3 ± 16.3, M/F = 28/21). Compared to HC, FD patients showed a widespread increase in R1 values encompassing both GM (pFWE = 0.02) and WM (pFWE = 0.02) structures. While no correlations were found between increased R1 values and FASTEX score, a significant negative correlation emerged between residual enzymatic activity levels and R1 values in GM (r = -0.57, p = 0.008) and WM (r = -0.49, p = 0.03).

CONCLUSIONS

We demonstrated the feasibility and clinical relevance of non-invasively assessing cerebral Gb3 accumulation in FD using MRI. R1 mapping might be used as an in-vivo quantitative neuroimaging biomarker in FD patients.

Inflammation and Exosomes in Fabry Disease Pathogenesis

Fabry Disease (FD) is one of the most prevalent lysosomal storage disorders, resulting from mutations in the GLA gene located on the X chromosome. This genetic mutation triggers glo-botriaosylceramide (Gb-3) buildup within lysosomes, ultimately impairing cellular functions. Given the role of lysosomes in immune cell physiology, FD has been suggested to have a profound impact on immunological responses. During the past years, research has been focusing on this topic, and pooled evidence strengthens the hypothesis that Gb-3 accumulation potentiates the production of pro-inflammatory mediators, revealing the existence of an acute inflammatory process in FD that possibly develops to a chronic state due to stimulus persistency. In parallel, extracellular vesicles (EVs) have gained attention due to their function as intercellular communicators. Considering EVs' capacity to convey cargo from parent to distant cells, they emerge as potential inflammatory intermediaries capable of transporting cytokines and other immunomodulatory molecules. In this review, we revisit the evidence underlying the association between FD and altered immune responses and explore the potential of EVs to function as inflammatory vehicles.

Impact of kidney biopsy on deciding when to initiate enzyme replacement therapy in children with Fabry disease

BACKGROUND

Recommendations on when to start enzyme replacement therapy (ERT) in children with Fabry disease (FD) differ between guidelines. In this study, kidney biopsies of a cohort of 14 untreated children and one treated child were analyzed for their morphologic changes to determine whether early initiation of ERT is indicated.

METHODS

All pediatric FD patients (< 18 years old) diagnosed between 2003 and 2021 in our department who received a kidney biopsy were enrolled. Clinical symptoms; laboratory parameters regarding kidney function, such as eGFR, plasma urea, protein-creatinine, and albumin/creatinine ratio; and 14 kidney biopsies prior to ERT and one under treatment were retrospectively analyzed.

RESULTS

A total of 14 patients were enrolled, including 9 male and 5 female children, aged 3-18 years (median age 11). Seven of the enrolled children were 10 years old or younger. Histological analysis of kidney biopsy samples revealed severe vacuolization and accumulation of inclusions in podocytes and renal tubules. The majority of cases had no FD-specific clinical or laboratory features independent of age, gender, or genotype. The youngest FD patient presenting with isolated abnormal kidney biopsy was 3 years old.

CONCLUSIONS

We demonstrate that histological lesions, typical for FD, can be observed in kidney biopsies at a very young age in patients without classical clinical symptoms or laboratory abnormalities. Thus, we recommend kidney biopsies as a possible tool for early diagnosis of renal involvement in FD. As a consequence of these early biopsy findings without a clinical correlate, an early initiation of ERT should be considered. A higher resolution version of the Graphical abstract is available as Supplementary information.

Effect of Migalastat on cArdiac InvOlvement in FabRry DiseAse: MAIORA study

BACKGROUND

A small but significant reduction in left ventricular (LV) mass after 18 months of migalastat treatment has been reported in Fabry disease (FD). This study aimed to assess the effect of migalastat on FD cardiac involvement, combining LV morphology and tissue characterisation by cardiac magnetic resonance (CMR) with cardiopulmonary exercise testing (CPET).

METHODS

Sixteen treatment-naïve patients with FD (4 women, 46.4±16.2 years) with cardiac involvement (reduced T1 values on CMR and/or LV hypertrophy) underwent ECG, echocardiogram, troponin T and NT-proBNP (N-Terminal prohormone of Brain Natriuretic Peptide) assay, CMR with T1 mapping, and CPET before and after 18 months of migalastat.

RESULTS

No change in LV mass was detected at 18 months compared to baseline (95.2 g/m2 (66.0-184.0) vs 99.0 g/m2 (69.0-121.0), p=0.55). Overall, there was an increase in septal T1 of borderline significance (870.0 ms (848-882) vs 860.0 ms (833.0-875.0), p=0.056). Functional capacity showed an increase in oxygen consumption (VO2) at anaerobic threshold (15.50 mL/kg/min (13.70-21.50) vs 14.50 mL/kg/min (11.70-18.95), p=0.02), and a trend towards an increase in percent predicted peak VO2 (72.0 (63.0-80.0) vs 69.0 (53.0-77.0), p=0.056) was observed. The subset of patients who showed an increase in T1 value and a reduction in LV mass (n=7, 1 female, age 40.5 (28.6-76.0)) was younger and at an earlier disease stage compared to the others, and also exhibited greater improvement in exercise tolerance.

CONCLUSION

In treatment-naïve FD patients with cardiac involvement, 18-month treatment with migalastat stabilised LV mass and was associated with a trend towards an improvement in exercise tolerance. A tendency to T1 increase was detected by CMR. The subset of patients who had significant benefits from the treatment showed an earlier cardiac disease compared to the others.

TRIAL REGISTRATION NUMBER

NCT03838237.

Difficulties in Diagnosing Fabry Disease in Patients with Unexplained Left Ventricular Hypertrophy (LVH): Is the Novel GLA Gene Mutation a Pathogenic Mutation or Polymorphism?

Fabry disease (FD) is an X-linked, lysosomal glycosphingolipid storage disorder that occurs very rarely. Cardiac involvement may comprise of left ventricular hypertrophy (LVH), arrhythmias, conduction abnormalities, heart failure and valvular abnormalities. The goal of this study was to conduct gene analysis for FD in patients suffering from unexplained LVH. 120 patients over the age of 30 who were diagnosed by echocardiography with idiopathic LVH were included in the study. Patients with severe hypertension, intermediate valve disease such as moderate aortic stenosis, known FD, and a family history of autosomal dominant hypertrophic cardiomyopathy were excluded from the study. GLA gene mutations were studied by Sanger sequence analysis in all patients. Of the 120 total patients included in this study, 69 were female (58%) and 51 were male (42%). The mean age was 60.3 ± 15.7. GLA gene mutations were detected in three male patients. The detected mutations are as follows: NM_000169.2:IVS6-10G>A (c.1000-10G>A), NM_000169.2:c.937G>T (p.D313Y) (p.Asp313Tyr) and NM_000169.2:c.941A>T (p.K314M) (p.Lys314Met). Early diagnosis is of vital importance in FD, which can be treated with enzyme replacement. Genetic screening in patients diagnosed with idiopathic LVH by echocardiography is important in the early diagnosis and treatment of FD. Patients over 30 years of age with idiopathic LVH should be screened for FD. Various new polymorphisms can be detected in genetic screening. Identifying new polymorphisms is important for knowing the true mutations in FD.

Prevalence of Fabry Disease in patients with left ventricular hypertrophy in Turkey: Multicenter study (LVH-TR subgroup analysis)

PURPOSE

In this prospective study we aimed to determine the rate of Fabry Disease (FD) in patients with left ventricular hypertrophy (LVH), and to evaluate the clinical presentations of patients with FD in a comprehensive manner. In addition, we aimed to raise awareness about this issue by allowing early diagnosis and treatment of FD.

METHODS

Our study was planned as national, multicenter, observational. Totally 22 different centers participated in this study. A total of 886 patients diagnosed with LVH by echocardiography (ECHO) were included in the study. Demographic data, biochemical parameters, electrocardiography (ECG) findings, ECHO findings, treatments and clinical findings of the patients were recorded. Dry blood samples were sent from male patients with suspected FD. The α-Gal A enzyme level was checked and genetic testing was performed in patients with low enzyme levels. Female patients suspected of FD were genetically tested with the GLA Gene Mutation Analysis.

RESULTS

FD was suspected in a total of 143 (16.13%) patients included in the study. The α-Gal-A enzyme level was found to be low in 43 (4.85%) patients whom enzyme testing was requested. GLA gene mutation analysis was positive in 14 (1.58%) patients. Male gender, E/e' mean ,and severe hypertrophy are important risk factor for FD.

CONCLUSION

In daily cardiology practice, FD should be kept in mind not only in adult patients with unexplained LVH but also in the entire LVH population. Dry blood test (DBS) should be considered in high-risk patients, and mutation analysis should be considered in required patients.

The prevalence of Fabry disease in a Turkish population with chronic kidney patients

BACKGROUND AND OBJECTIVES

Fabry disease (FD) is an X-linked lysosomal storage disease with various clinical symptoms due to a deficiency of an enzyme called alpha-galactosidase A. The likelihood of nephropathy increases with age and the severity of the mutation in Fabry patients. Fabry disease is difficult to diagnose. The exact incidence and prevalence of Fabry disease are unknown due to its atypical or oligosymptomatic forms.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

GLA gene mutations were examined in patients over the age of 18 who were followed up on with a diagnosis of chronic kidney disease and who had or did not receive renal replacement therapy from October 2017 to December 2019.

RESULTS

A total of 18 sites in 8 locations around Turkey volunteered to participate in the study, including people aged 18 and older with stages 1-5 of chronic kidney disease (CKD) or getting renal replacement therapy. 1904 patients were screened in total. In 13 cases, a D313Y pseudo mutation in the GLA gene was discovered. GLA gene mutations were found and pathologically assessed in four of the tested cases.

CONCLUSIONS

The range of clinical symptoms of Fabry disease, as well as the frequent delays in diagnosis, result in treatment being too late. We believe that screening chronic renal patients at high risk for Fabry disease is warranted.

Comparative analysis of phasic left atrial strain and left ventricular posterolateral strain pattern to discriminate Fabry cardiomyopathy from other forms of left ventricular hypertrophy

BACKGROUND

"Classical" echocardiographic signs of Fabry cardiomyopathy (FC), such as left ventricular hypertrophy (LVH), posterolateral strain impairment (PLSI), and papillary muscle hypertrophy may be of limited diagnostic accuracy in clinical practice. Our aim was to evaluate the diagnostic value of left atrial (LA) strain impairment compared to "classical" echocardiographic findings to discriminate FC.

METHODS

In standard echocardiographic assessments, we retrospectively analyzed the diagnostic value of the "classical" red flags of FC as well as LA strain in 20 FC patients and in 20 subjects with other causes of LVH. Receiver operating characteristic (ROC) curve analysis was performed to assess the respective diagnostic accuracy.

RESULTS

FC was confirmed in 20 patients by genetic testing. In the LVH group, 12 patients were classified by biopsy to have hypertrophic cardiomyopathy, two had hypertensive heart disease, and six LVH combined with borderline myocarditis. Global and regional left ventricular (LV) strain was not significantly different between groups while LA strain was significantly impaired in FC (Left atrial reservoir strain (LASr) 19.1%±8.4 in FC and 25.6%±8.9 in LVH, p = 0.009; left atrial conduction strain (LAScd) -8.4%±4.9 in FC and -15.9%±8.4 in LVH, p < 0.01). LAScd, with an area under the curve (AUC) of .81 (95% confidence interval [CI] .66-.96) showed the highest diagnostic accuracy to discriminate FC. The PLSI pattern showed an AUC of .49, quantification of papillary muscle hypertrophy an AUC of .47.

CONCLUSION

Adding LA strain analysis to a comprehensive echocardiographic work-up of unclear LVH may be helpful to identify FC as a possible cause.

Recognition of pre-hypertrophic cardiac involvement in Fabry Disease based on automated electrocardiographic measures

BACKGROUND

Various electrocardiographic (ECG) indices have been shown to be useful for early recognition and staging of cardiac involvement in Fabry Disease (FD). However, many of them lack acceptable sensitivity and specificity. We assessed the value of automated ECG measures to discriminate between pre-hypertrophic FD and healthy individuals.

METHODS AND RESULTS

Normal ECGs from 1496 healthy individuals (57.4% male, age 37.4 ± 13 years) were compared to those of 142 FD patients without LVH (37.3% male, age 41.5 ± 18 years). All ECGs were analyzed centrally and a total of 429 automated ECG measures per individual were included for step-wise analysis. The Cramer V statistic was first used to pick out those parameters which were helpful in discriminating between the two groups and a final selection was made by using two models, namely the FLD (Fisher Linear Discrimination) and the Logistic model, to optimise diagnostic performance for the detection of cardiac involvement in FD patients vs. specificity in healthy individuals. The three-step statistical analysis identified 9 ECG parameters as most significant for the discrimination between the groups. The combined discriminant score yielded 64% sensitivity and 97% specificity for correct classification of FD patients in the test sample with a logistic area under curve of the ROC analysis of 0.97.

CONCLUSION

The combination of automated ECG measures identified via a stepwise statistical approach may be useful for detection of FD patients in the pre-hypertrophic stage. These data are promising for screening purposes in the very early stages of FD cardiomyopathy and warrant prospective confirmation.

Update on Neuropathies in Inborn Errors of Metabolism

Neuropathies are relatively common in inborn errors of metabolism (IEMs); however, due to the early onset and severe, progressive course of many IEMs, they have not been very well researched yet. This article aims to review and compare neuropathies in inborn errors of metabolism, mostly with childhood and juvenile onset. Some of these diseases are treatable if diagnosed early and in many cases, the therapy can not only slow down disease progression, but can also reverse the changes already made by the condition.

Hypertrophy of unaffected cardiomyocytes correlates with severity of cardiomyopathy in female patients with Fabry disease

Aim

To investigate the contribution of unaffected cardiomyocytes in Fabry disease cardiomyopathy.

Findings

Left ventricular (LV) endomyocardial biopsies from twenty-four females (mean age 53 ± 11 ys) with Fabry disease cardiomyopathy were studied. Diagnosis of FD was based on the presence of pathogenic GLA mutation, Patients were divided in four groups according with LV maximal wall thickness (MWT): group 1 MWT ≤ 10.5 mm, group 2 MWT 10.5–15 mm, group 3 MWT 16–20 mm, group 4 MWT > 20 mm. At histology mosaic of affected and unaffected cardiomyocytes was documented. Unaffected myocytes’ size ranged from normal to severe hypertrophy. Hypertrophy of unaffected cardiomyocytes correlated with severity of MWT (p < 0.0001, Sperman r 0,95). Hypertrophy of unaffected myocytes appear to concur to progression and severity of FDCM. It is likely a paracrine role from neighboring affected myocytes.

Fabry cardiomyopathy: Gb3-induced auto-reactive panmyocarditis requiring heart transplantation

Resistance to enzyme replacement therapy (ERT) is a major therapeutic challenge in Fabry disease (FD). Recent reports attribute to immune‐mediated inflammation a main role in promoting disease progression and resistance to ERT. Aim of the study is to report a Gb3‐induced auto‐reactive panmyocarditis causing inefficacy of ERT and severe electrical instability, which required cardiac transplantation. Examining the explanted heart from a 57‐year‐old man with FD cardiomyopathy (CM) on 3‐year ERT presenting incoming ventricular fibrillation, we documented a severe virus‐negative myocarditis extended to cardiomyocytes, intramural coronary vessels, conduction tissue, and subepicardial ganglia. Serology was positive for anti‐Gb3, anti‐heart, and anti‐myosin antibodies. In vitro Gb3 stimulation of patient's peripheral blood mononuclear cells (PBMC) induced high amount production of inflammatory cytokine IL1‐β, IL‐6, IL‐8, and TNF‐α. PBMC were stained using the monoclonal antibodies CD3‐V500, CD4‐V450, CD8‐APCcy7, CD45RO‐PerCPcy5.5 and CD27‐FITC from BD Biosciences and CD56‐PC7 from Bekman Coulter. The phenotypic analysis of PBMC showed a lower frequency of CD8 (9.2%) vs. 19.3% and NKT cells (1.6% vs. 2.4%) in Fabry patient respect to healthy donor, suggesting a possible homing to peripheral tissues. A Gb3‐induced auto‐reactive myocarditis is suggested as a possible cause of FDCM progression and ERT resistance. Immune‐mediated inflammation of systemic Fabry cells may coexist and be controlled by implemental immunosuppressive therapy.

Prevalence of Fabry Disease in Korean Men with Left Ventricular Hypertrophy

BACKGROUND

Fabry disease is an X-linked recessive disorder caused by deficiency of the lysosomal enzyme α-galactosidase A (α-Gal A). Previous studies identified many cases of Fabry disease among men with left ventricular hypertrophy (LVH). The purpose of this study was to define the frequency of Fabry disease among Korean men with LVH.

METHODS

In this national prospective multicenter study, we screened Fabry disease in men with LVH on echocardiography. The criterion for LVH diagnosis was a maximum LV wall thickness 13 mm or greater. We screened 988 men with LVH for plasma α-Gal A activity. In patients with low α-Gal A activity (< 3 nmol/hr/mL), we searched for mutations in the α-galactosidase gene.

RESULTS

In seven men, α-Gal A activity was low. Three had previously identified mutations; Gly328Arg, Arg301Gln, and His46Arg. Two unrelated men had the E66Q variant associated with functional polymorphism. In two patients, we did not detect GLA mutations, although α-Gal A activity was low on repeated assessment.

CONCLUSION

We identified three patients (0.3%) with Fabry disease among unselected Korean men with LVH. Although the prevalence of Fabry disease was low in our study, early treatment of Fabry disease can result in a good prognosis. Therefore, in men with unexplained LVH, differential diagnosis of Fabry disease should be considered.

Lysosomal storage disorders affecting the heart: a review

Lysosomal storage disorders (LSD) comprise a group of diseases caused by a deficiency of lysosomal enzymes, membrane transporters or other proteins involved in lysosomal biology. Lysosomal storage disorders result from an accumulation of specific substrates, due to the inability to break them down. The diseases are classified according to the type of material that is accumulated; for example, lipid storage disorders, mucopolysaccharidoses and glycoproteinoses. Cardiac disease is particularly important in lysosomal glycogen storage diseases (Pompe and Danon disease), mucopolysaccharidoses and in glycosphingolipidoses (Anderson-Fabry disease). Various disease manifestations may be observed including hypertrophic and dilated cardiomyopathy, coronary artery disease and valvular diseases. Endomyocardial biopsies can play an important role in the diagnosis of these diseases. Microscopic features along with ancillary tests like special stains and ultrastructural studies help in the diagnosis of these disorders. Diagnosis is further confirmed based upon enzymatic and molecular genetic analysis. Emerging evidence suggests that Enzyme replacement therapy (ERT) substantially improves many of the features of the disease, including some aspects of cardiac involvement. The identification of these disorders is important due to the availability of ERT, the need for family screening, as well as appropriate patient management and counseling.

Development and clinical consequences of white matter lesions in Fabry disease: a systematic review

BACKGROUND

Fabry disease (FD) is a rare lysosomal storage disorder that might result in, amongst other complications, early stroke and white matter lesions (WMLs). More insight in WMLs in FD could clarify the role of WMLs in the disease presentation and prognosis in FD. In this systematic review we assessed the prevalence, severity, location and course of WMLs in FD. We also systematically reviewed the evidence on the relation between WMLs, disease characteristics and clinical parameters.

METHODS

We searched Pubmed, EMBASE and CINAHL (inception to Feb 2018) and identified articles reporting on FD and WMLs assessed with MRI. Prevalence and severity were assessed for all patients combined and divided by sex.

RESULTS

Out of 904 studies a total of 46 studies were included in the analyses. WMLs were present in 46% of patients with FD (581 out of 1276 patients, corrected mean age: 38.8 years, range 11.8-79.3) and increased with age. A total of 16.4% of patients (31 out of 189 patients, corrected mean age: 41.1 years, range 35.8-43.3 years) showed substantial confluent WMLs. Men and women showed comparable prevalence and severity of WMLs. However, men were significantly younger at time of WML assessment. Patients with classical FD had a higher chance on WMLs compared to non-classical patients. Progression of WMLs was seen in 24.6% of patients (49 out of 199 patients) during 38.1 months follow-up. Progression was seen in both men and women, with and without enzyme replacement therapy, but at an earlier age in men. Stroke seemed to be related to WMLs, but cerebrovascular risk factors, cardiac and renal (dys)function did not. Pathology in the brain in FD seemed to extend beyond the WMLs into the normal appearing white matter.

CONCLUSIONS

A significant group of FD patients has substantial WMLs and male patients develop WMLs earlier compared to female patients. WMLs could be used in clinical trials to evaluate possible treatment effects on the brain. Future studies should focus on longitudinal follow-up using modern imaging techniques, focusing on the clinical consequences of WMLs. In addition, ischemic and non-ischemic pathways resulting in WML development should be studied.

Multiple sclerosis and fabry Disease, two sides of the coin? The case of an Italian family

BACKGROUND

Multiple Sclerosis (MS) is considered among possible differential diagnosis of Fabry Disease (FD), especially in early stages when findings are suggestive but not diagnostic for MS. We report the case of a family in which FD and MS coexist, offering an overview on clues for differential diagnosis and speculating on shared etiopathogenic mechanisms for these conditions.

METHODS

Taking as starting point the diagnosis of FD in a dialysis patient during a screening programme, we retrospectively rebuilt his family history and revised clinical and imaging examinations of his five siblings, two of which with previous diagnosis of MS.

RESULTS

After genetic testing, two subjects were found positive to a new α-galactosidase A mutation, probably causative for FD classical variant. The two subjects meeting diagnostic criteria for MS were found negative to any GLA gene mutation, therefore initial diagnosis was confirmed. The remaining two siblings resulted unaffected, with neither clinical nor instrumental evidence of FD and MS.

CONCLUSIONS

Differential diagnosis between FD and MS may be challenging, especially in early clinical stages when only extensive clinical evaluation and correct MRI interpretation may reduce the risk of misdiagnosis. Moreover this report allows speculating on potential etiological and pathogenic mechanisms, common both to FD and MS.

Long-Term Dose-Dependent Agalsidase Effects on Kidney Histology in Fabry Disease

BACKGROUND AND OBJECTIVES

Dose-dependent clearing of podocyte globotriaosylceramide has previously been shown in patients with classic Fabry disease treated with enzyme replacement. Our study evaluates the dose-dependent effects of agalsidase therapy in serial kidney biopsies of patients treated for up to 14 years.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Twenty patients with classic Fabry disease (12 men) started enzyme replacement therapy at a median age of 21 (range =7-62) years old. Agalsidase-α or -β was prescribed for a median of 9.4 (range =5-14) years. The lower fixed dose group received agalsidase 0.2 mg/kg every other week throughout the follow-up period. The higher dose group received a range of agalsidase doses (0.2-1.0 mg/kg every other week). Dose changes were made due to disease progression, suboptimal effect, or agalsidase-β shortage. Serial kidney biopsies were performed along with clinical assessment and biomarkers and scored according to recommendations from the International Study Group of Fabry Nephropathy.

RESULTS

No statistical differences were found in baseline or final GFR or albuminuria. Kidney biopsies showed significant reduction of podocyte globotriaosylceramide in both the lower fixed dose group (-1.39 [SD=1.04]; P=0.004) and the higher dose group (-3.16 [SD=2.39]; P=0.002). Podocyte globotriaosylceramide (Gb3) reduction correlated with cumulative agalsidase dose (r=0.69; P=0.001). Arterial/arteriolar intima Gb3 cleared significantly in the higher dose group, all seven patients with baseline intimal Gb3 cleared the intima, one patient gained intimal Gb3 inclusions (P=0.03), and medial Gb3 did not change statistically in either group. Residual plasma globotriaosylsphingosine levels remained higher in the lower fixed dose group (20.1 nmol/L [SD=11.9]) compared with the higher dose group (10.4 nmol/L [SD=8.4]) and correlated with cumulative agalsidase dose in men (r=0.71; P=0.01).

CONCLUSIONS

Reduction of podocyte globotriaosylceramide was found in patients with classic Fabry disease treated with long-term agalsidase on different dosing regimens, correlating with cumulative dose. Limited clearing of arterial/arteriolar globotriaosylceramide raises concerns regarding long-term vascular effects of current therapy. Residual plasma globotriaosylsphingosine correlated with cumulative dose in men.

Fabry Disease in Southern Sardinia: epidemiological results from screening in an extensive area

INTRODUCTION

Epidemiological data relating to the prevalence and incidence of Fabry disease (FD) and other Lysosomal Storage diseases (LSDs) are largely underestimated and not yet well known. Distribution of the disease varies according to geographical area and to ethnic origin. Heterozygous females are also at risk of contracting severe and multi-symptomatic forms of FD.

AIM

To demonstrate the results obtained in outpatient surgeries situated in an area comprising 319,340 inhabitants.

METHODS

Out of a total of 2710 nephrologist visits, 150 patients with suspected FD (73 undergoing dialysis and 77 conservative management) were selected. The relatives of one female patient on dialysis who had tested positive were investigated and a further 11 patients thus identified (total: 4 males and 7 females) within a micro-area of 21,822 inhabitants, i.e. a prevalence rate of one positive case every 1,818 inhabitants. These data relate to the first 18 months of screening.

CONCLUSIONS

In the field of nephrology, patients with high levels of proteinuria or microalbuminuria (150-200 mg/day) should be screened for FD, particularly in areas with a high incidence and/or prevalence of kidney disease. Once positive patients of both sexes have been identified, they should immediately be referred for cardiologic and neurological assessment.

Ultrastructural deposits appearing as "zebra bodies" in renal biopsy: Fabry disease?- comparative case reports

Background

Fabry Disease (FD) is a genetic disorder caused by alpha-galactosidase A deficiency. Certain drugs, such as hydroxychloroquine, can produce renal deposits that mimic morphological findings seen in FD, characterizing a type of drug-induced renal phospholipidosis.

Case presentation

Case 1: A 28-year-old female patient with systemic lupus erythematosus who had been using hydroxychloroquine for 14 months presented subnephrotic proteinuria. Renal biopsy showed deposits compatible with FD. Neither activity analysis of alpha-galactosidase A nor genetic analysis were available and were not performed. These deposits were not detected in a subsequent renal biopsy three years after withdrawal of the medication, characterizing a possible hydroxychloroquine-induced renal phospholipidosis. Case 2: A 29-year-old male patient presented with acroparesthesia, angiokeratomas, cornea verticillata and subnephrotic proteinuria. Deposits compatible with FD were detected upon renal biopsy. The evaluation of alpha-galactosidase A showed no activity in both blood and leukocytes. Genetic analysis identified an M284 T mutation in exon 6, and such mutation was also found in other family members.

Conclusion

Clinical investigation is necessary in suspected cases of Fabry Disease upon renal biopsy in order to confirm diagnosis. Drug-induced renal phospholipidosis should be considered in differential diagnosis in cases with intracellular osmiophilic, lamellar inclusions in electron microscopy.

Evaluation of oxidative stress markers and cardiovascular risk factors in Fabry Disease patients

Fabry Disease, an X-linked inborn error of metabolism, is characterized by progressive renal insufficiency, with cardio and cerebrovascular involvement. Homocysteine (Hcy) is considered a risk factor for vascular diseases, but the mechanisms by which it produces cardiovascular damage are still poorly understood. Regarding the vascular involvement in FD patients, the analysis of factors related to thromboembolic events could be useful to improving our understanding of the disease. The aim of this study was to evaluate plasma Hcy and other parameters involved in the methionine cycle, as well as oxidative stress markers. The sample consisted of a group of 10 male FD patients and a control group of 8 healthy individuals, paired by age. Venous blood was collected for Hcy determination, molecular analysis, identification of thiobarbituric acid reactive substances, total glutathione and antioxidant enzymes activity, as well as vitamins quantification. Comparative analysis of FD patients versus the control group indicated hyperhomocysteinemia in 8 of the 10 FD patients, as well as a significant increase in overall glutathione levels and catalase activity. It is inferred that FD patients, apart from activation of the antioxidant system, present increased levels of plasma Hcy, although this is probably unrelated to common alterations in the methionine cycle.

A case of Fabry's disease with congenital agammaglobulinemia

Fabry's disease is an X-linked lysosomal storage disorder caused by abnormalities in the α-galactosidase A (GLA) gene, which leads to a GLA deficiency and to the intracellular deposition of globotriaosylceramide (Gb3) within vascular endothelium and other tissues. It manifests as progressive multiple organ dysfunctions caused by the deposition of Gb3. On the other hand, congenital agammaglobulinemia is usually caused by mutations in Bruton's tyrosine kinase (Btk) gene with X-linked dominence, suppresses B cell maturation, and causes recurrent pyogenic infections. In former reports, the distance between the loci in the Xq22 region of the human X chromosome was found to be about 69 kilobases. A 23-yr-old man diagnosed with congenital agammaglobulinemia at age 5, showed typical clinical and laboratory and histopathological findings of Fabry's disease. The genetic basis of this combination of the two syndromes was studied in this patient. Here, we report a case of Fabry's disease with congenital agammaglobulinemia.

Fabry disease - current treatment and new drug development

Fabry disease is a rare inherited lysosomal storage disorder caused by a partial or complete deficiency of α-galactosidase A (GLA), resulting in the storage of excess cellular glycosphingolipids. Enzyme replacement therapy is available for the treatment of Fabry disease, but it is a costly, intravenous treatment. Alternative therapeutic approaches, including small molecule chaperone therapy, are currently being explored. High throughput screening (HTS) technologies can be utilized to discover other small molecule compounds, including non-inhibitory chaperones, enzyme activators, molecules that reduce GLA substrate, and molecules that activate GLA gene promoters. This review outlines the current therapeutic approaches, emerging treatment strategies, and the process of drug discovery and development for Fabry disease.