João Paulo Oliveira

Nephropathy in males and females with Fabry disease : cross-sectional description of patients before treatment with enzyme replacement therapy

BACKGROUND Fabry disease, an X-linked genetic disorder with deficient alpha-galactosidase A activity, is characterized by kidney disease and kidney failure. The spectrum of kidney disease has not been well defined, especially in female patients. METHODS We did a cross-sectional retrospective analysis of natural history of glomerular filtration rate (estimated- eGFR), albuminuria and proteinuria in 1262 adult patients (585 males, 677 females) from the Fabry Registry. RESULTS Twenty-eight percent of males (age 20-79 years) and 13% of females (age 20-82 years) had chronic kidney disease (CKD) with eGFR < 60 ml/min/1.73 m(2). Overt proteinuria (>300 mg/24 h) was demonstrated in 43 and 26% of males and females with CKD stage 1, respectively, and the proportions were higher with more severe kidney involvement. However, 11% of males and 28% of females with eGFR < 60 ml/min/1.73 m(2) had proteinuria <300 mg/ 24 h. Of eGFR >/= 60 ml/min/1.73 m(2) patients without overt proteinuria (n = 93), 55% of the males and 35% of the females had albuminuria >30 mg/24 h. Systemic blood pressure was >/=130/80 mmHg in 48% and 67% of patients with eGFR >/= and <60 ml/min/1.73 m(2), respectively, with no significant differences between males and females. Proteinuria values were significantly correlated with systolic blood pressure in both sexes. CONCLUSIONS Kidney involvement in Fabry disease is more prevalent and heterogeneous than previously reported. Proteinuria is an early complication, but may not be overt in patients with advanced kidney disease. This analysis, which includes more females than males, confirms that a significant proportion of females suffer moderate to severe kidney involvement in Fabry disease.

Renal outcomes of agalsidase beta treatment for Fabry disease: role of proteinuria and timing of treatment initiation

Background. The purpose of this study was to identify determinants of renal disease progression in adults with Fabry disease during treatment with agalsidase beta. Methods. Renal function was evaluated in 151 men and 62 women from the Fabry Registry who received agalsidase beta at an average dose of 1 mg/kg/2 weeks for at least 2 years. Patients were categorized into quartiles based on slopes of estimated glomerular filtration rate (eGFR) during treatment. Multivariate logistic regression analyses were used to identify factors associated with renal disease progression. Results. Men within the first quartile had a mean eGFR slope of –0.1 mL/min/1.73m2/year, whereas men with the most rapid renal disease progression (Quartile 4) had a mean eGFR slope of –6.7 mL/min/1.73m2/year. The risk factor most strongly associated with renal disease progression was averaged urinary protein:creatinine ratio (UP/Cr) ≥1 g/g (odds ratio 112, 95% confidence interval (95% CI) 4–3109, P = 0.0054). Longer time from symptom onset to treatment was also associated with renal disease progression (odds ratio 19, 95% CI 2–184, P = 0.0098). Women in Quartile 4 had the highest averaged UP/Cr (mean 1.8 g/g) and the most rapid renal disease progression: (mean slope –4.4 mL/min/1.73m2/year). Conclusions. Adults with Fabry disease are at risk for progressive loss of eGFR despite enzyme replacement therapy, particularly if proteinuria is ≥1 g/g. Men with little urinary protein excretion and those who began receiving agalsidase beta sooner after the onset of symptoms had stable renal function. These findings suggest that early intervention may lead to optimal renal outcomes.

Mutations of the GLA Gene in Young Patients With Stroke The PORTYSTROKE Study—Screening Genetic Conditions in PORTuguese Young STROKE Patients

Background and Purpose— Fabry disease is an X-linked monogenic disorder caused by mutations in the GLA gene. Recent data suggest that stroke in young adults may be associated with Fabry disease. We aimed to ascertain the prevalence of this disorder among young adult patients with stroke in Portugal by GLA genotyping. Methods— During 1 year, all patients aged 18 to 55 years with first-ever stroke, who were admitted into any of 12 neurology hospital departments in Portugal, were prospectively enrolled (n=625). Ischemic stroke was classified according to Trial of Org 10172 in Acute Stroke Treatment criteria. Alpha-galactosidase activity was further assayed in all patients with GLA mutations. Results— Four hundred ninety-three patients (mean age, 45.4 years; 61% male) underwent genetic analyses: 364 with ischemic stroke, 89 with intracerebral hemorrhage, 26 with subarachnoid hemorrhage, and 14 with cerebral venous thrombosis. Twelve patients had missense GLA mutations: 9 with ischemic stroke (p.R118C: n=4; p.D313Y: n=5), including 5 patients with an identified cause of stroke (cardiac embolism: n=2; small vessel disease: n=2; other cause: n=1), 2 with intracerebral hemorrhage (p.R118C: n=1; p.D313Y: n=1), and one with cerebral venous thrombosis (p.R118C: n=1). Leukocyte &agr;-galactosidase activity was subnormal in the hemizygous males and subnormal or low-normal in the heterozygous females. Estimated prevalence of missense GLA mutations was 2.4% (95% CI, 1.3% to 4.1%). Conclusions— Despite a low diagnostic yield, screening for GLA mutations should probably be considered in different types of stroke. Restricting investigation to patients with cryptogenic stroke may underestimate the true prevalence of Fabry disease in young patients with stroke.

Scoring system for renal pathology in Fabry disease: report of the International Study Group of Fabry Nephropathy (ISGFN)

BACKGROUND In Fabry nephropathy, alpha-galactosidase deficiency leads to accumulation of glycosphingolipids in all kidney cell types, proteinuria and progressive loss of kidney function. METHODS An international working group of nephrologists from 11 Fabry centres identified adult Fabry patients, and pathologists scored histologic changes on renal biopsies. A standardized scoring system was developed with a modified Delphi technique assessing 59 Fabry nephropathy cases. Each case was scored independently of clinical information by at least three pathologists with an average final score reported. RESULTS We assessed 35 males (mean age 36.4 years) and 24 females (43.9 years) who mostly had clinically mild Fabry nephropathy. The average serum creatinine was 1.3 mg/dl (114.9 micromol/l); estimated glomerular filtration rate was 81.7 ml/min/1.73 m(2) and urine protein to creatinine ratio was 1.08 g/g (122.0 mg/mmol). Males had greater podocyte vacuolization on light microscopy (mean score) and glycosphingolipid inclusions on semi-thin sections than females. Males also had significantly more proximal tubule, peritubular capillary and vascular intimal inclusions. Arteriolar hyalinosis was similar, but females had significantly more arterial hyalinosis. Chronic kidney disease stage correlated with arterial and glomerular sclerosis scores. Significant changes, including segmental and global sclerosis, and interstitial fibrosis were seen even in patients with stage 1-2 chronic kidney disease with minimal proteinuria. CONCLUSIONS The development of a standardized scoring system of both disease-specific lesions, i.e. lipid deposition related, and general lesions of progression, i.e. fibrosis and sclerosis, showed a spectrum of histologic appearances even in early clinical stage of Fabry nephropathy. These findings support the role of kidney biopsy in the baseline evaluation of Fabry nephropathy, even with mild clinical disease. The scoring system will be useful for longitudinal assessment of prognosis and responses to therapy for Fabry nephropathy.

Prognostic indicators of renal disease progression in adults with Fabry disease: natural history data from the Fabry Registry.

BACKGROUND AND OBJECTIVES These analyses were designed to characterize renal disease progression in untreated adults with Fabry disease. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Data from the Fabry Registry for 462 untreated adults (121 men and 341 women) who had at least two estimated GFR (eGFR) values over a span of ≥12 months before starting enzyme replacement therapy were included. RESULTS Most men (86 of 121, 71%) had more rapid loss of kidney function than the normal adult population (loss of eGFR > -1 ml/min per 1.73 m(2) per year), whereas fewer women (133 of 341, 39%) had rapid loss of kidney function. Patients with rapid progression had significantly higher mean averaged urinary protein to urinary creatinine ratios (UP/Cr) than patients with slower progression (1.5 versus 0.2 for men; 1.4 versus 0.5 for women; P < 0.0001). Patients were grouped into quartiles based on averaged UP/Cr; renal function in men declined more rapidly with higher UP/Cr, with the steepest declines observed in men with UP/Cr > 1.5 (mean eGFR slope, -5.6 ml/min per 1.73 m(2) per year; n = 30). eGFR slope declined more slowly in women, with the steepest declines observed in women with UP/Cr > 1.2 (mean eGFR slope, -1.3 ml/min per 1.73 m(2) per year; n = 85). Regression models of eGFR slope indicated that UP/Cr is the most important indicator of renal disease progression in adult Fabry patients. In women, lower baseline eGFR and age were also associated with renal disease progression. Women who had clinical events had more rapid loss of kidney function. CONCLUSIONS Urinary protein excretion is strongly associated with renal disease progression in men and women with Fabry disease.

End-stage renal disease in patients with Fabry disease: natural history data from the Fabry Registry

BACKGROUND Fabry disease, an X-linked lysosomal storage disorder caused by deficiency of alpha-galactosidase activity, is associated with progressive loss of kidney function. This study was undertaken to characterize Fabry disease among patients who reached end-stage renal disease. METHODS Data from 2,712 patients in the Fabry Registry were analysed to identify clinical characteristics of patients who received renal replacement therapy (RRT) during the natural history period (i.e. prior to any enzyme replacement therapy). RESULTS A total of 213 patients [186 of 1,359 males (14%) and 27 of 1,353 females (2%)] received RRT at a median age of 38 years in both males and females. Males who received RRT were diagnosed at a median age of 35 years, compared to 23 years for non-RRT males. Sixty-one males and 10 females were not diagnosed with Fabry disease until after they had received RRT. Compared to other Fabry Registry patients, a higher percentage of RRT patients also experienced either a serious cardiovascular event or a stroke. Ninety-two of 186 males who had RRT (50%) experienced a cardiac event or stroke, compared to 230 of 1,173 non-RRT males (20%). Ten of 27 RRT females (37%) had experienced a cardiac event or stroke, compared to 226 of 1,326 non-RRT females (17%). Patients who had RRT experienced cardiovascular events and strokes at earlier ages than did patients who had not received RRT, and most received RRT before having a cardiac event or stroke. CONCLUSIONS While all Fabry patients are at risk of cardiovascular events and strokes, patients with Fabry nephropathy who develop kidney failure appear to have concurrent involvement of other major organ systems. It is important that Fabry patients are diagnosed early and that their renal function is monitored carefully.

Recommendations and guidelines for the diagnosis and treatment of Fabry nephropathy in adults

Progressive loss of kidney function complicates Fabry disease, an X-linked lysosomal storage disorder that arises from deficiency of α-galactosidase activity. Heterozygous females with Fabry disease can be as severely affected as hemizygous males, who have the classic form of the disease. Enzyme-replacement therapy with recombinant human α-galactosidase clears the glycosphingolipid globotriaosylceramide from kidney cells, and can stabilize renal function in adults with mild to moderate Fabry nephropathy. However, adults with more advanced nephropathy and overt proteinuria do not respond as well. For these patients, antiproteinuric therapy given in conjunction with enzyme-replacement therapy might prevent further decline in kidney function. In this Review, we propose guidelines and recommendations for the diagnosis and management of Fabry nephropathy in adults, based on published data and on the consensus of opinion of participants in the 7th International Fabry Nephropathy Roundtable in 2007. These organ-specific guidelines could be easier to implement than general guidelines, provided they are used in the context of an overall multisystem care approach.

How well does urinary lyso-Gb3 function as a biomarker in Fabry disease?

BACKGROUND Fabry disease is characterized by accumulation of glycosphingolipids, such as globotriaosylceramide (Gb(3)), in many tissues and body fluids. A novel plasma biomarker, globotriaosylsphingosine (lyso-Gb(3)), is increased in patients with the disease. Until now, lyso-Gb(3) was not detectable in urine, possibly because of the presence of interfering compounds. METHODS We undertook to: 1) characterize lyso-Gb(3) in urine; 2) develop a method to quantitate urinary lyso-Gb(3) by mass spectrometry; 3) evaluate urinary lyso-Gb(3) as a potential biomarker for Fabry disease; and 4) determine whether lyso-Gb(3) is an inhibitor of α-galactosidase A activity. We analyzed urinary lyso-Gb(3) from 83 Fabry patients and 77 healthy age-matched controls. RESULTS The intraday and interday bias and precision of the method were <15%. Increases in lyso-Gb(3)/creatinine correlated with the concentrations of Gb(3) (r(2)=0.43), type of mutations (p=0.0006), gender (p<0.0001) and enzyme replacement therapy status (p=0.0012). Urine from healthy controls contained no detectable lyso-Gb(3). Lyso-Gb(3) did not inhibit GLA activity in dried blood spots. Increased urinary excretion of lyso-Gb(3) of Fabry patients correlated well with a number of indicators of disease severity. CONCLUSION Lyso-Gb(3) is a reliable independent biomarker for clinically important characteristics of Fabry disease.

Fibrosis: A key feature of Fabry disease with potential therapeutic implications

Fabry disease is a rare X-linked hereditary disease caused by mutations in the AGAL gene encoding the lysosomal enzyme alpha-galactosidase A. Enzyme replacement therapy (ERT) is the current cornerstone of Fabry disease management. Involvement of kidney, heart and the central nervous system shortens life span, and fibrosis of these organs is a hallmark of the disease. Fibrosis was initially thought to result from tissue ischemia secondary to endothelial accumulation of glycosphingolipids in the microvasculature. However, despite ready clearance of endothelial deposits, ERT is less effective in patients who have already developed fibrosis. Several potential explanations of this clinical observation may impact on the future management of Fabry disease. Alternative molecular pathways linking glycosphingolipids and fibrosis may be operative; tissue injury may recruit secondary molecular mediators of fibrosis that are unresponsive to ERT, or fibrosis may represent irreversible tissue injury that limits the therapeutic response to ERT. We provide an overview of Fabry disease, with a focus on the assessment of fibrosis, the clinical consequences of fibrosis, and recent advances in understanding the cellular and molecular mechanisms of fibrosis that may suggest novel therapeutic approaches to Fabry disease.

Nephropathy in Fabry disease: the importance of early diagnosis and testing in high-risk populations*

1Department of Nephrology, University Hospital of Lund, Sweden, 2Renal Division, Brigham and Women’s Hospital, Boston, MA, USA, 3Departments of Nephrology and of Human Genetics, Faculty of Medicine, Hospital Sao Joao, Porto, Portugal, 4Department of Nephrology, Fundacion Jimenez Diaz, Universidad Autonoma de Madrid, Madrid, Spain, 5Department of Medicine, University of Muenster, Muenster, Germany, 6Medical Department, Haukeland University Hospital and Institute of Medicine, University of Bergen, Bergen, Norway, 7Division of Nephrology, Department of Medicine, University of Wurzburg, Germany, 8Genzyme Corp., Framingham, MA and 9Division of Nephrology, Department of Medicine and Physiology, University of Alabama, Birmingham, AL, USA