Vitamin C Urinary Loss in Fabry Disease: Clinical and Genomic Characteristics of Vitamin C Renal Leak

BACKGROUND

Reduced plasma vitamin C concentrations in chronic diseases may result from abnormal urinary excretion of vitamin C: a renal leak. We hypothesized that vitamin C renal leak may be associated with disease-mediated renal dysregulation, resulting in aberrant vitamin C renal reabsorption and increased urinary loss.

OBJECTIVES

We investigated the prevalence, clinical characteristics, and genomic associations of vitamin C renal leak in Fabry disease, an X-linked lysosomal disease associated with renal tubular dysfunction and low plasma vitamin C concentrations.

METHODS

We conducted a non-randomized cross-sectional cohort study of men aged 24-42 y, with Fabry disease (n = 34) and controls without acute or chronic disease (n = 33). To match anticipated plasma vitamin C concentrations, controls were placed on a low-vitamin C diet 3 wk before inpatient admission. To determine the primary outcome of vitamin C renal leak prevalence, subjects were fasted overnight, and matched urine and fasting plasma vitamin C measurements were obtained the following morning. Vitamin C renal leak was defined as presence of urinary vitamin C at plasma concentrations below 38 μM. Exploratory outcomes assessed the association between renal leak and clinical parameters, and genomic associations with renal leak using single nucleotide polymorphisms (SNPs) in the vitamin C transporter SLC23A1.

RESULTS

Compared with controls, the Fabry cohort had 16-fold higher odds of renal leak (6% vs. 52%; OR: 16; 95% CI: 3.30, 162; P < 0.001). Renal leak was associated with higher protein creatinine ratio (P < 0.01) and lower hemoglobin (P = 0.002), but not estimated glomerular filtration rate (P = 0.54). Renal leak, but not plasma vitamin C, was associated with a nonsynonymous single nucleotide polymorphism in vitamin C transporter SLC23A1 (OR: 15; 95% CI: 1.6, 777; P = 0.01).

CONCLUSIONS

Increased prevalence of renal leak in adult men with Fabry disease may result from dysregulated vitamin C renal physiology and is associated with abnormal clinical outcomes and genomic variation.

Heat shock protein 90 and NFkB levels in serum and urine in patients with chronic glomerulonephritis

Heat shock proteins play an important role in immune inflammation and the formation and restoration of proteins. In recent years, the importance of heat shock protein 90 (Hsp90) in the activation of immune inflammation through nuclear factor kB (NFkB) has been discussed. To assess the activation of the Hsp90-NFkB system by measuring serum and urinary levels in patients with chronic glomerulonephritis (CGN). This study included 32 patients with active forms of CGN and 14 patients with Fabry nephropathy. The control group included 10 healthy individuals. Twenty-one out of 32 CGN patients had nephrotic syndrome (NS). Eleven out of 32 CGN patients had proteinuria levels from 1 to 3 g/day without nephrotic syndrome. A total of 17 patients had renal dysfunction (estimated glomerular filtration rate < 60 ml/min/1.73m2). Fourteen patients with Fabry nephropathy had proteinuria without nephrotic syndrome. Serum and urine HSP-90 and NFkB p65 levels were determined using an enzyme-linked immunosorbent assay. The levels of HSP-90 and NFkB in the serum of patients with CGN were significantly higher than in healthy individuals and patients with Fabry nephropathy. In patients with Fabry nephropathy, the HSP-90 and NFkB levels in the urine and serum did not significantly differ from those in the control subjects. Serum Hsp90 levels were significantly higher in the CGN patients with NS than in patients without NS, as well as in patients with normal renal function compared with patients with an eGFR < 60 ml/min/1.73 m2 and patients with tubulo-interstitial fibrosis. Higher levels of HSP-90 and NFkB in serum were observed in patients with nephrotic forms of CGN, including focal segmental glomerulosclerosis, minimal change disease and membranous nephropathy. There were no correlations between the clinical signs of CGN and urinary HSP90/NFkB levels. Activation of the HSP-90-NFkB system, which is directly involved in the development of immune inflammation in CGN, was found in patients with an active course of CGN, especially in those with nephrotic syndrome.

Pharmacokinetics, pharmacodynamics, and safety of moss-aGalactosidase A in patients with Fabry disease

Moss-aGalactosidase A (moss-aGal) is a moss-derived version of human α-galactosidase developed for enzyme replacement therapy in patients with Fabry disease. It exhibits a homogenous N-glycosylation profile with >90% mannose-terminated glycans. In contrast to mammalian cell produced α-galactosidase, moss-aGal does not rely on mannose-6-phosphate receptor mediated endocytosis but targets the mannose receptor for tissue uptake. We conducted a phase 1 clinical trial with moss-aGal in six patients with confirmed diagnosis of Fabry disease during a 28-day schedule. All patients received a single dose of 0.2 mg/kg moss-aGal by i.v.-infusion. Primary endpoints of the trial were safety and pharmacokinetics; secondary endpoints were pharmacodynamics by analyzing urine and plasma Gb3 and lyso-Gb3 concentrations. In all patients, the administered single dose was well tolerated. No safety issues were observed. Pharmacokinetic data revealed a stable nonlinear profile with a short plasma half-life of moss-aGal of 14 minutes. After one single dose of moss-aGal, urinary Gb3 concentrations decreased up to 23% 7 days and up to 60% 28 days post-dose. Plasma concentrations of lyso-Gb3 decreased by 3.8% and of Gb3 by 11% 28 days post-dose. These data reveal that a single dose of moss-aGal was safe, well tolerated, and led to a prolonged reduction of Gb3 excretion. As previously shown, moss-aGal is taken up via the mannose receptor, which is expressed on macrophages but also on endothelial and kidney cells. Thus, these data indicate that moss-aGal may target kidney cells. After these promising results, phase 2/3 clinical trials are in preparation.

Podocyturia in paediatric patients with Fabry disease

INTRODUCTION

Fabry disease (FD) is a hereditary disorder caused by a deficiency of α-galactosidase A enzyme activity. The transmission of the disorder is linked to the X chromosome.

OBJECTIVES

The objectives of the study were: 1. To quantify the presence of podocytes in paediatric patients with FD and compare them with the value of the measured podocyturia in healthy controls. 2. To determine whether a greater podocyturia is related to the onset of pathological albuminuria in patients with FD. 3. To determine the risk factors associated with pathological albuminuria.

METHODS

We performed an analytical, observational study of Fabry and control subjects, which were separated into 2groups in accordance with the absence of the disease (control group) or the presence of the disease (Fabry group).

RESULTS

We studied 31 patients, 11 with FD and 20 controls, with a mean age of 11.6 years. The difference between the mean time elapsed from the diagnosis of FD to the measurement of podocyturia (40 months) and the onset of pathological albuminuria (34 months) was not significant (p=0.09). Podocytes were identified by staining for the presence of synaptopodin and the mean quantitative differences between both podocyturias were statistically significant (p=0.001). Albuminuria was physiological in 4 of the patients with FD and the relative risk to develop pathological albuminuria according to podocyturia was 1.1 in the control group and 3.9 in the Fabry group, with a coefficient of correlation between podocyturia and albuminuria in the Fabry group of 0.8354. Finally, the 2 risk factors associated with the development of pathological albuminuria were podocyturia (OR: 14) and being aged over 10 years (OR: 18). We found no significant risk with regard to glomerular filtrate renal (GFR) (OR: 0.5) or gender (OR: 1.3). The mean GFR remained within normal values.

CONCLUSION

The detection of podocyturia in paediatric patients with FD could be used as an early marker of renal damage, preceding and proportional to the occurrence of pathological albuminuria.

Mulberries in the urine: a tell-tale sign of Fabry disease

Fabry disease is a treatable progressive illness of inborn error causing eventual multiple organ dysfunction in advanced untreated cases. We report on a classic Fabry child patient presenting with urinary mulberry cells and bodies without renal involvement. This report emphasizes the usefulness of urinary microscopic findings in the early diagnosis of Fabry disease.

Globotriaosylsphingosine (Lyso-Gb3) as a biomarker for cardiac variant (N215S) Fabry disease

Fabry disease (FD) is a multi-systemic X-linked lysosomal disorder caused by the deficient activity of α-galactosidase-A enzyme, which leads to accumulation of glycosphingolipids in various body tissues. The N215S mutation is a known variant of FD, with a late onset cardiac phenotype. Consensus guidelines acknowledged the use of globotriaosylsphingosine (Lyso-Gb₃) as a diagnostic marker for classical FD but its utility for cardiac variant FD is not clear. We aim to characterize the clinical features and evaluate the diagnostic accuracy of plasma and urinary Lyso-Gb₃ levels in N215S cardiac variant FD patients. Thirty-four FD patients with the late-onset N215S cardiac variant mutation were enrolled along with 62 classical FD patients and 109 healthy controls. Plasma and urinary Lyso-Gb₃ and its analogues were analyzed by LC-MS/MS. Both FD males and females with N215S mutation showed Lyso-Gb₃ levels of (mean ± SEM) 9.7 ± 1.0 and 5.4 ± 0.8 nM, respectively. These levels were significantly higher than healthy control and lower than classical FD patients (p < 0.0001). Plasma Lyso-Gb₃ levels equal to or higher than 2.7 nM yielded a diagnostic sensitivity and specificity of 100% (AUC = 1, p < 0.0001). Cardiac involvement was frequent with 16/34 (47%) developing left ventricular hypertrophy. Three patients who underwent renal biopsy had the characteristic sphingolipid deposition in the podocytes while 6/19 (32%) had evidence of white matter changes or infarct on brain MRI. Taken together, cardiac variant N215S mutation is rather an attenuated form of classical FD. Plasma Lyso-Gb₃ is a diagnostic hallmark to differentiate N215S variant phenotype from subjects with no FD.

New biomarkers defining a novel early stage of Fabry nephropathy: A diagnostic test study

BACKGROUND

Renal involvement in Fabry disease is a major determinant of overall disease prognosis and early enzyme replacement therapy seems effective in preventing progression of kidney injury. Gb3 storage, glomerular sclerosis and tubulo-interstitial fibrosis may occur with minimal or no changes on standard renal tests, hence alternative markers of renal dysfunction are crucial. In this study we compared several biomarkers with albuminuria in the identification of incipient Fabry nephropathy and their diagnostic accuracy to identify chronic kidney disease (CKD) stage≥2.

METHODS

In this multicentre, prospective, cross-sectional and diagnostic test study, a cohort of 78 Fabry patients and 25 healthy controls was consecutively recruited. Patients were grouped by severity of nephropathy: 1) albuminuria<30mg/g; 2) albuminuria 30-299mg/g; 3) albuminuria>300mg/g; 4) glomerular filtration rate (GFR)<60mL/min/1.73m². Several index tests, namely biomarkers of glomerular (transferrin and type IV collagen) and tubular (α1-microglobulin, N-acetyl-β-glucosaminidase and alanine aminopeptidase) dysfunction were compared with the reference standard (albuminuria).

RESULTS

Significant increase of all tested biomarkers in Fabry patients, even in the subgroup of patients without evidence of nephropathy. We also found inverse significant correlations between estimated GFR and collagen type IV (ρ=-0.289; p=0.003) or N-acetyl-β-glucosaminidase (ρ=-0.448; p<0.001), which were stronger than with albumin (ρ=-0.274; p=0.019). There was also better diagnostic accuracy of N-acetyl-β-glucosaminidase to predict CKD stage≥2.

CONCLUSIONS

These results suggest that studied biomarkers may overcome the limitations of albuminuria as sensitive marker of early renal dysfunction and as marker for CKD progression risk. These biomarkers may also define novel early stages of nephropathy characterized by mesangial expansion and/or tubular damage.

Lipiduria--with special relevance to Fabry disease

Examination of the urine under the microscope using polarised light is invaluable for detecting and identifying lipid particles. Attention to the shape of these Maltese cross bearing bodies can distinguish conventional fat particles from Fabry bodies with great sensitivity and specificity across a wide phenotypic spectrum. This could be a cheap and rapid tool for screening subjects suspected of having Fabry disease for renal involvement. It remains to be seen whether there is value in integrating polarised light into automated urine microscopy machines, but potentially this could greatly help the pathologist or nephrologist in identifying unusual urinary particles, and broaden the capacity for larger scale screening.

A Novel Rapid MALDI-TOF-MS-Based Method for Measuring Urinary Globotriaosylceramide in Fabry Patients

Fabry disease is an X-linked lysosomal storage disorder caused by deficiency of α-galactosidase A, resulting in the accumulation of glycosphingolipids in various organs. Globotriaosylceramide (Gb3) and its isoforms and analogues have been identified and quantified as biomarkers of disease severity and treatment efficacy. The current study aimed to establish rapid methods for urinary Gb3 extraction and quantitation. Urine samples from 15 Fabry patients and 21 healthy control subjects were processed to extract Gb3 by mixing equal volumes of urine, methanol containing an internal standard, and chloroform followed by sonication and centrifugation. Thereafter, the lower phase was analyzed by MALDI-TOF MS and the relative peak areas of the internal standard and four major species of Gb3 determined. The results showed high reproducibility with intra- and inter-assay coefficients variation of 9.9% and 13.7%, respectively. The limit of detection was 0.15 ng/μL and the limit of quantitation was 0.30 ng/μL. Total urinary Gb3 levels in both genders of classic Fabry patients were significantly higher than in healthy controls (p < 0.0001). Gb3 levels in Fabry males were higher than in Fabry females (p = 0.08). We have established a novel assay for urinary total Gb3 that takes less than 15 min from start to finish. Graphical Abstract ᅟ.

A Renal Variant of Fabry Disease Diagnosed by the Presence of Urinary Mulberry Cells

Fabry disease is a lysosomal storage disorder caused by a deficiency of α-galactosidase A. This disease is classified into two types, namely a classical and variant type. We herein present the case of a 36-year-old man who showed a renal variant of Fabry disease and was diagnosed at an early stage by the presence of mulberry cells. He had no history of general symptoms except for proteinuria. The presence of mulberry cells caused us to suspect Fabry disease and he was thereafter diagnosed to have a renal variant of Fabry disease based on the findings of a renal biopsy, a mutation analysis and a low level of α-galactosidase A activity.

Variations in the GLA gene correlate with globotriaosylceramide and globotriaosylsphingosine analog levels in urine and plasma

Recent data have shown that lyso-Gb3, the deacylated derivative of globotriaosylceramide (Gb3), is possibly involved in the pathogenesis of Fabry disease (FD) and might be a clinically useful biomarker of its metabolic load. To test this hypothesis, we assayed Gb3 and lyso-Gb3 and related analogs in plasma and/or urine samples of 12 clinically well-characterized subjects carrying several different GLA variant alleles associated with a wide range of residual α-galactosidase A activities. Urinary Gb3 was measured by HPLC-MS/MS; plasma and urinary lyso-Gb3 and related analogs were measured by UPLC-MS/MS. Individual profiles of Gb3 and lyso-Gb3 and related analogs closely correlated with the phenotypic data for each subject, discerning the classical FD patient from the two patients carrying cardiac variants as well as those from all the others without FD. The lyso-Gb3 analog at m/z 836 was found at increased levels only in patients manifesting clinically severe heart disease, irrespective of the pathogenicity of the GLA variant they carried. This finding suggests that this lyso-Gb3 analog might be an earlier biomarker of progressive heart disease, non-specific of the FD cardiomyopathy. The possibility that urinary Gb3 is a specific marker of kidney involvement in FD deserves further study.

Characterization of early disease status in treatment-naive male paediatric patients with Fabry disease enrolled in a randomized clinical trial

Trial Design

This analysis characterizes the degree of early organ involvement in a cohort of oligo-symptomatic untreated young patients with Fabry disease enrolled in an ongoing randomized, open-label, parallel-group, phase 3B clinical trial.

Methods

Males aged 5–18 years with complete α-galactosidase A deficiency, without symptoms of major organ damage, were enrolled in a phase 3B trial evaluating two doses of agalsidase beta. Baseline disease characteristics of 31 eligible patients (median age 12 years) were studied, including cellular globotriaosylceramide (GL-3) accumulation in skin (n = 31) and kidney biopsy (n = 6; median age 15 years; range 13–17 years), renal function, and glycolipid levels (plasma, urine).

Results

Plasma and urinary GL-3 levels were abnormal in 25 of 30 and 31 of 31 patients, respectively. Plasma lyso-GL-3 was elevated in all patients. GL-3 accumulation was documented in superficial skin capillary endothelial cells (23/31 patients) and deep vessel endothelial cells (23/29 patients). The mean glomerular filtration rate (GFR), measured by plasma disappearance of iohexol, was 118.1 mL/min/1.73 m² (range 90.4–161.0 mL/min/1.73 m²) and the median urinary albumin/creatinine ratio was 10 mg/g (range 4.0–27.0 mg/g). On electron microscopy, renal biopsy revealed GL-3 accumulation in all glomerular cell types (podocytes and parietal, endothelial, and mesangial cells), as well as in peritubular capillary and non-capillary endothelial, interstitial, vascular smooth muscle, and distal tubules/collecting duct cells. Lesions indicative of early Fabry arteriopathy and segmental effacement of podocyte foot processes were found in all 6 patients.

Conclusions

These data reveal that in this small cohort of children with Fabry disease, histological evidence of GL-3 accumulation, and cellular and vascular injury are present in renal tissues at very early stages of the disease, and are noted before onset of microalbuminuria and development of clinically significant renal events (e.g. reduced GFR). These data give additional support to the consideration of early initiation of enzyme replacement therapy, potentially improving long-term outcome.

Trial Registration

ClinicalTrials.gov NCT00701415

Metabolomic discovery of novel urinary galabiosylceramide analogs as Fabry disease biomarkers

Fabry disease is an X-linked, complex, multisystemic lysosomal storage disorder presenting marked phenotypic and genotypic variability among affected male and female patients. Glycosphingolipids, mainly globotriaosylceramide (Gb(3)) isoforms/analogs, globotriaosylsphingosine (lyso-Gb(3)) and analogs, as well as galabiosylceramide (Ga(2)) isoforms/analogs accumulate in the vascular endothelium, nerves, cardiomyocytes, renal glomerular and tubular epithelial cells, and biological fluids. The search for biomarkers reflecting disease severity and progression is still on-going. A metabolomic study using quadrupole time-of-flight mass spectrometry has revealed 22 galabiosylceramide isoforms/analogs in urine of untreated Fabry patients classified in seven groups according to their chemical structure: (1) Saturated fatty acid; (2) one extra double bond; (3) two extra double bonds; (4) hydroxylated saturated fatty acid; (5) hydroxylated fatty acid and one extra double bond; (6) hydrated sphingosine and hydroxylated fatty acid; (7) methylated amide linkage. Relative quantification of both Ga(2) and Gb(3) isoforms/analogs was performed. All these biomarkers are significantly more abundant in urine samples from untreated Fabry males compared with healthy male controls. A significant amount of Ga(2) isoforms/analogs, accounting for 18% of all glycosphingolipids analyzed (Ga(2) + Gb(3) and respective isoforms/analogs), were present in urine of Fabry patients. Gb(3) isoforms containing saturated fatty acids are the most abundant (60.9%) compared with 26.3% for Ga(2). A comparison between Ga(2) isoforms/analogs and their Gb(3) counterparts also showed that the proportion of analogs with hydroxylated fatty acids is significantly greater for Ga(2) (35.8%) compared with Gb(3) (1.9%). These results suggest different biological pathways involved in the synthesis and/or degradation of Gb(3) and Ga(2) metabolites.

Risk of death in heart disease is associated with elevated urinary globotriaosylceramide

Background

Elevated urinary globotriaosylceramide (Gb₃) has been considered a hallmark of Fabry disease, an X‐linked lysosomal disorder that is a risk factor for most types of heart disease.

Methods and Results

We screened 1421 consecutive patients with common forms of heart disease for Fabry disease by measuring urinary Gb₃ in whole urine using tandem mass spectrometry, α‐galactosidase A activity in dried blood spots, and we looked for GLA mutations by parallel sequencing of the whole gene (exons and introns) in pooled genomic DNA samples followed by Sanger sequencing verification. GLA variants were found in 13 patients. In the 1408 patients without GLA mutations, urinary Gb₃ levels were significantly higher in heart disease patients compared to 116 apparently healthy controls (median difference=10.0 ng/mL and P<0.001). Urinary lipid profiling showed that levels of 5 other lipids significantly distinguished between urine of patients with Fabry disease (n=7) and heart disease patients with elevated urinary Gb₃ (n=6). Sphingomyelin and Gb₃ levels were abnormal in the left ventricular wall of patients with ischemic heart failure. Elevated levels of urinary Gb₃ were independently associated with increased risk of death in the average follow‐up of 17 months (hazard ratio=1.59 for increase in Gb₃ of 200, 95% CI=1.36 and 1.87, and P<0.0001).

Conclusions

In heart disease patients who do not have Fabry disease or GLA gene mutations, a higher level of urinary Gb₃ is positively associated with near‐term mortality. The elevation of urinary Gb₃ and that of other lipids suggests that heart disease is associated with multiorgan lipid abnormalities.

Clinical Trial Registration

URL: clinicaltrials.gov. Unique Identifier: NCT01019629.

Long-term effect of antibodies against infused alpha-galactosidase A in Fabry disease on plasma and urinary (lyso)Gb3 reduction and treatment outcome

INTRODUCTION

Enzyme replacement therapy (ERT) with alpha-Galactosidase A (aGal A) may cause antibody (AB) formation against aGal A in males with Fabry disease (FD). Anti agalsidase ABs negatively influence globotriaosylceramide (Gb3) reduction. We investigated the impact of agalsidase AB on Gb3 and lysoGb3 and clinical outcome in Fabry patients on ERT.

METHODS

Adult male and female patients on ERT for at least one year were included. Urinary Gb3 was measured by HPLC, plasma lysoGb3 by LC-ESI-MS/MS and AB with a neutralization assay.

RESULTS

Of the 59 patients evaluable patients, 0/30 females and 17/29 males developed anti-agalsidase antibodies (AB+). Only 3/17 males had transient (low) titers (tolerized). All AB+ patients developed antibodies during the first year of treatment. Change of agalsidase preparation (or dose) did not induce antibody formation. AB+ males had significant less decline in plasma lysoGb3 compared to AB- males (p = 0.04). Urinary Gb3 levels decreased markedly in AB- but remained comparable to baseline in AB+ males (p<0.01). (Lyso)Gb3 reduction in plasma and urine on ERT was correlated with LVmass reduction in females and development white matter lesions and stroke.

CONCLUSION

In male patients antibodies against aGal A remained present up to 10 years of ERT. The presence of these antibodies is associated with a less robust decrease in plasma lysoGb3 and a profound negative effect on urinary Gb3 reduction, which may reflect worse treatment outcome.

A distinct urinary biomarker pattern characteristic of female Fabry patients that mirrors response to enzyme replacement therapy

Female patients affected by Fabry disease, an X-linked lysosomal storage disorder, exhibit a wide spectrum of symptoms, which renders diagnosis, and treatment decisions challenging. No diagnostic test, other than sequencing of the alpha-galactosidase A gene, is available and no biomarker has been proven useful to screen for the disease, predict disease course and monitor response to enzyme replacement therapy. Here, we used urine proteomic analysis based on capillary electrophoresis coupled to mass spectrometry and identified a biomarker profile in adult female Fabry patients. Urine samples were taken from 35 treatment-naïve female Fabry patients and were compared to 89 age-matched healthy controls. We found a diagnostic biomarker pattern that exhibited 88.2% sensitivity and 97.8% specificity when tested in an independent validation cohort consisting of 17 treatment-naïve Fabry patients and 45 controls. The model remained highly specific when applied to additional control patients with a variety of other renal, metabolic and cardiovascular diseases. Several of the 64 identified diagnostic biomarkers showed correlations with measures of disease severity. Notably, most biomarkers responded to enzyme replacement therapy, and 8 of 11 treated patients scored negative for Fabry disease in the diagnostic model. In conclusion, we defined a urinary biomarker model that seems to be of diagnostic use for Fabry disease in female patients and may be used to monitor response to enzyme replacement therapy.

Elevation of urinary globotriaosylceramide (GL3) in infants with Fabry disease

BACKGROUND

Fabry disease is caused by a deficiency of α-galactosidase A (α-Gal A), which results in the accumulation of globotriaosylceramide (GL3) and related glycosphingolipids in different organs. Urinary GL3 levels increase in symptomatic Fabry disease patients, but it is not clear whether urinary GL3 excretion also increases in young or pre-symptomatic patients.

SUBJECTS AND METHODS

Eighty-nine newborns with leukocyte α-Gal A activities of less than 30% of the normal mean were discovered by newborn screening. Urine samples were collected on filter paper, and GL3 levels were measured using liquid chromatography-tandem mass spectrometry.

RESULTS

Five newborns with classic Fabry disease mutations all had elevated urinary GL3 levels (mean=5.2 mg/mmol creatinine (creat.), range=0.80-14.39, normal <0.6). Among the 84 newborns with later-onset mutations, 45 (54%) had a mild elevation of urinary GL3 levels (mean=1.1 mg/mmol creat., range=0.60-3.07, normal <0.6). The urinary GL3 levels decreased in all newborns over the course of a three-year follow-up period. However, four children with classic mutations and seven with IVS4+919G>A mutations still had elevated GL3 levels at the end of the study.

CONCLUSION

Elevated urinary GL3 levels can be present at birth in Fabry disease patients, suggesting an early involvement of the kidneys in this disease. The increased urinary GL3 excretion in those with later-onset mutations supports a pathogenic role for these mutations.

Substrate reduction augments the efficacy of enzyme therapy in a mouse model of Fabry disease

Fabry disease is an X-linked glycosphingolipid storage disorder caused by a deficiency in the activity of the lysosomal hydrolase α-galactosidase A (α-gal). This deficiency results in accumulation of the glycosphingolipid globotriaosylceramide (GL-3) in lysosomes. Endothelial cell storage of GL-3 frequently leads to kidney dysfunction, cardiac and cerebrovascular disease. The current treatment for Fabry disease is through infusions of recombinant α-gal (enzyme-replacement therapy; ERT). Although ERT can markedly reduce the lysosomal burden of GL-3 in endothelial cells, variability is seen in the clearance from several other cell types. This suggests that alternative and adjuvant therapies may be desirable. Use of glucosylceramide synthase inhibitors to abate the biosynthesis of glycosphingolipids (substrate reduction therapy, SRT) has been shown to be effective at reducing substrate levels in the related glycosphingolipidosis, Gaucher disease. Here, we show that such an inhibitor (eliglustat tartrate, Genz-112638) was effective at lowering GL-3 accumulation in a mouse model of Fabry disease. Relative efficacy of SRT and ERT at reducing GL-3 levels in Fabry mouse tissues differed with SRT being more effective in the kidney, and ERT more efficacious in the heart and liver. Combination therapy with ERT and SRT provided the most complete clearance of GL-3 from all the tissues. Furthermore, treatment normalized urine volume and uromodulin levels and significantly delayed the loss of a nociceptive response. The differential efficacies of SRT and ERT in the different tissues indicate that the combination approach is both additive and complementary suggesting the possibility of an improved therapeutic paradigm in the management of Fabry disease.

Perspectives of 1H-NMR-based urinary metabonomics in Fabry disease

High resolution proton magnetic resonance spectroscopy (1H-NMR) of body fluids coupled with multivariate data analysis has led to a new science known as metabonomics. Metabonomics is a powerful tool for investigating any disturbance in the normal homeostasis of biochemical processes. In particular, urine metabonomics provides information on the metabolite phenotype of the human being and is therefore appropriate to study the status of the global system. Here we applied 1H-NMR-based urinary metabonomics in a perspective study of the inherited lysosomal storage disorder known as Fabry disease, starting from the metabolite profiling of urine samples of male and female naïve Fabry subjects. Here we show that the 2 groups of patients can be fairly clearly separated into 2 classes due to statistically significant differences in the urinary level of some metabolites. This preliminary study shows that metabonomics can potentially be used for characterizing the biochemical mechanisms underlying the disease and, hopefully, for early diagnosis of Fabry disease.

Fabry disease: perspectives of urinary proteomics

Fabry disease (FD) is an X-linked lysosomal storage disorder caused by mutations in the gene encoding the lysosomal enzyme a-galactosidase A (a-GalA). The resulting deficiency in a-GalA activity leads to intra-lysosomal accumulation of neutral glycosphingolipids, mainly globotriaosylceramide (Gb3), in various organ systems. As a consequence, a multisystem disorder develops, culminating in strokes and progressive renal and cardiac dysfunction. Enzyme replacement therapy (ERT) offers a specific treatment for patients affected by FD, though monitoring treatment is hampered by a lack of surrogate markers of response. Furthermore, even if signs and symptoms of the disease become manifest in childhood, its diagnosis is often delayed. Biomarkers that predict disease progression and respond relatively quickly to effective therapy may be useful to follow individual patients or groups of patients. Here we report the use of 2 different mass spectrometry-based proteomic techniques to identify disease-associated compositional changes that can be used as early biomarkers of the pathology, as well as for monitoring the effectiveness of ERT. To this purpose, we compared the renal Fabry urinary proteome with normal (control) urine using, respectively, 2-dimensional gel electrophoresis and label-free quantification. Our preliminary results show that the urinary protein pattern of affected patients can be easily distinguished from that of healthy subjects both qualitatively and quantitatively, thus encouraging further studies in the search for FD-specific biomarkers using this proteomic approach.

Fabry disease urinary globotriaosylceramide/creatinine biomarker evaluation by liquid chromatography-tandem mass spectrometry in healthy infants from birth to 6 months

Fabry disease is an X-linked lysosomal storage disorder caused by deficiency of alpha-galactosidase A, resulting in accumulation of the principal substrate, globotriaosylceramide (Gb(3)), in various physiological fluids and tissues in affected patients. The recognition that accumulation of Gb(3) begins in utero, combined with the fact that the diagnosis of the disease is often delayed until after the development of irreversible tissue damage, has generated pressure to develop techniques for the early, pre-symptomatic diagnosis of the disease. Measurements of urinary Gb(3) have been shown to be useful for the diagnosis of Fabry disease in adults. The objective of this work was to measure the Gb(3)/creatinine biomarker in urine of healthy infants from birth to 6 months, including the establishment of reference ranges for urinary Gb(3) excretion at various postnatal ages, in male and female infants. We employed liquid chromatography-tandem mass spectrometry (LC-MS/MS) to determine Gb(3)/creatinine ratios in urine specimens dried on filter paper and mailed to the laboratory by participating parents. A total of 728 urine specimens were obtained at intervals from birth to 6 months of age from 68 healthy infants (35 male and 33 female). Parental participation was good, with 90% of the expected specimens received by the laboratory. The results of the analyses were grouped by the age of the infants into four periods. We have determined that both postnatal age and sex have an effect on urinary Gb(3) excretion levels which vary considerably in newborns. We conclude that screening for Fabry disease by measurement of urinary Gb(3) excretion is unlikely to be reliable before 30 days of age.

Relationship between biochemical and clinical features in an English Anderson-Fabry family

The relationship between biochemical parameters and clinical symptoms in angiokeratoma corporis diffusum universale (Anderson-Fabry's disease) has been studied in an extensive English family. The biochemical parameters measured were alpha-galactosidase activity in urine and in single hair roots and the urinary glycosphingolipid excretion per 24 h. The clinical symptoms evaluated included the occurrence of pain, the prevalence of skin lesions, an abnormal ECG, cornea verticillata and other features. Nine male patients and 13 female carriers were studied. No correlation between biochemical parameters and the severity of the clinical symptoms could be found either in the hemizygotes or in the heterozygotes. The urinary alpha-galactosidase activity in all the heterozygotes lay within the normal range. All the obligate heterozygotes (mothers and daughters of hemizygotes) could be detected by analysis of hair roots. Additional heterozygotes were recognized on the basis of clinical symptoms and hair root analysis.

Proposed high-risk screening protocol for Fabry disease in patients with renal and vascular disease

Fabry disease is a complex, multisystemic and clinically heterogeneous disease with prominent urinary excretion of globotriaosylceramide (Gb(3)), the principal substrate of the deficient enzyme, alpha-galactosidase A. Some measure of specific treatment is possible with enzyme replacement therapy, which can be applied safely and effectively to Fabry patients. Incidence estimations of Fabry disease vary widely from 1:55 000 to 1:3000 male births. The true incidence is likely to be higher than originally thought, owing to the existence of milder variants of the disease. The main complications of Fabry disease are a 100-fold increased risk of ischaemic stroke, cardiac disease, a wide variety of arrhythmias, valvular dysfunction and cardiac vascular disease, as well as progressive renal failure usually associated with significant proteinuria. These clinical manifestations are non-specific and are often mistaken for symptoms of other disorders, thus complicating the confirmation of diagnosis. Other clinical features of the disease are often absent (angiokeratoma), subtle (corneal opacities and hypohidrosis), or unaccompanied by specific physical findings (acroparaesthesias) indicating the true nature of the underlying disease. We propose the hypothesis that alpha-galactosidase A deficiency is a modifiable cardiovascular risk factor in the general population. This hypothesis may be tested by a non-invasive high-risk screening protocol for Fabry patients with ischaemic strokes and a variety of cardiac, and renal complications. These patients would benefit from diagnosis, appropriate treatment, follow-up and surveillance. Early detection of Fabry patients would also benefit affected relatives, many of whom do not have a clear diagnosis of their clinical condition.

Treatment of Fabry disease with different dosing regimens of agalsidase: effects on antibody formation and GL-3

Two different enzyme preparations are used for the treatment of Fabry disease patients, agalsidase alpha (Replagal, Shire) and agalsidase beta (Fabrazyme, Genzyme). Therapeutic efficacy of both products has been variable probably due to differences in gender, severity, age and other patient characteristics. We studied the occurrence of alpha-Gal A antibodies and their effect on urinary and plasma globotriaosylceramide (GL-3), plasma chitotriosidase and clinical outcome in 52 patients after 12 months of treatment with either 0.2mg/kg agalsidase alppha (10 males, 8 females) or beta (8 males, 5 females) or 1.0mg/kg agalsidase beta (10 males, 11 females). Antibodies were detected in 18/28 male patients after 6 months. None of the females developed antibodies. Following 12 months of 0.2mg/kg treatment, urinary GL-3 decreased in antibody negative (AB-) but increased in antibody positive (AB+) patients. Treatment with 1.0mg/kg gave a reduction in urinary GL-3 in both AB- and AB+ patients. Levels of plasma GL-3 and chitotriosidase decreased in all patient groups. Twelve months of 0.2mg/kg treatment did not change renal function or left ventricular mass. Further, no change in renal function was seen following 1.0mg/kg treatment and left ventricular mass decreased in both AB- and AB+ patients. In summary, alpha-Gal A antibodies frequently develop in male Fabry disease patients and interfere with urinary GL-3 excretion. Infusion of a dose of 1.0mg/kg results in a more robust decline in GL-3, less impact, if any of antibodies, stable renal function and reduction of LVMass.

Influence of antibody formation on reduction of globotriaosylceramide (GL-3) in urine from Fabry patients during agalsidase beta therapy

Two recombinant human agalsidase preparations are available for treatment of Fabry disease. We assayed urinary GL-3 (uGL-3) concentration in seronegative and seropositive patients receiving agalsidase beta (1mg/kg). Antibody formation and residual enzyme activity were strongly correlated. Normalization of uGL-3 was achieved more efficiently in seronegatives. But different from previous reports, reduction of uGL-3 level was observed in some seropositive patients.

Fabry disease in a heterozygote presenting as hand ischaemia and painful acroparaesthesia

A 48-year-old woman presented with acute unilateral ischaemia of the left hand. She had a background of chronic peripheral neuropathic pain, palpitations, anaemia and an episode of superficial thrombophlebitis. Physical examination revealed non-blanching purple discoloration of her left fingers and her left thumb, index finger and thenar eminance appeared ischaemic. Digital subtraction angiography of the left hand demonstrated reduced flow. Skin punch biopsy histology was unremarkable. The diagnosis of Fabry disease was made on urine lipid profile analysis and confirmed by reduced peripheral blood leukocyte alpha-galactosidase A activity.

Development of a filter paper method potentially applicable to mass and high-risk urinary screenings for Fabry disease

Fabry disease is an X-linked lysosomal storage disorder of glycosphingolipid catabolism resulting from a deficiency of the enzyme alpha-galactosidase A, and leading to the progressive accumulation of one biomarker, globotriaosylceramide (Gb(3)), predominantly elevated in the urine of these patients. We have developed a technique for the analysis of total Gb(3) in urine samples collected on filter paper, using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with a triple quadrupole instrument. Existing Gb(3) techniques being both time- and labour-intensive, this filter paper method eliminates lipid extraction, glycolipid isolation, centrifugation and evaporation steps, while maintaining sensitivity and efficiency. The stability of Gb(3) on filter paper was good for a 7-week period under different temperature conditions. Normal control values were established and the technique was tested with anonymized samples from Fabry hemizygotes and heterozygotes. The levels of total Gb(3) in all classical hemizygotes were well above the control values and all heterozygotes, except two nonexcretors, were above the reference level. The proposed novel filter paper method favours the collection, storage and shipment of samples. It is simple and efficient for a feasibility study, potentially applicable to the determination of total urinary Gb(3) in the newborn population as part of a screening programme, and could also be used in high-risk screening laboratories. Since the incidence of Fabry disease is hard to establish, owing to the heterogeneous clinical expression of the visible phenotype, this feasibility study could help determine its actual incidence in the Quebec population.

Atmospheric pressure photoionization coupled to porous graphitic carbon liquid chromatography for the analysis of globotriaosylceramides. Application to Fabry disease

Globotriaosylceramides (Gb(3)) are biological compounds implicated in Fabry disease, a lysosomal storage disease due to the deficient activity of alpha-D-galactosidase A, which results in an accumulation of Gb(3) in many organs. The naturally occurring samples are composed of mixtures of several molecular species differing by the structure of the alkyl chains and the nature of the sphingoid base. Atmospheric pressure photoionization mass spectrometry (APPI-MS) proved to be an efficient method for the analysis of globotriaosylceramide molecular species, both in direct injection and by coupling with liquid chromatography (LC). In the positive ion mode, in-source fragmentations yield very precious information that can be used to determine the structure of the alkyl chains. In the negative ion mode, the chloroform solvent participates to the analyte ionization by forming an adduct with chloride ions generated in situ. Combination of LC on a Porous Graphitic Carbon stationary phase and APPI-MS allowed the detection of a great number of species from biological samples isolated from Fabry patients. This method could be an interesting analytical tool for the biochemical investigation of (sphingo) lipid metabolism.

Enzyme replacement therapy for Fabry disease: Morphologic and histochemical changes in the urinary sediments

BACKGROUND

Fabry disease is an X-linked lysosomal storage disease resulting from deficient activity of the enzyme alpha-galacotsidase A. Accumulation of glycosphingolipids, especially globotriaosylceramide, leads to renal damage in Fabry disease. In patients with Fabry disease, the urinary sediment contains excreted glycosphingolipids. With enzyme replacement therapy for Fabry disease now currently available, we examined whether the urinary sediment could be used to noninvasively monitor effectiveness of enzyme replacement therapy.

METHODS

Four male patients with hemizygous classical Fabry disease received recombinant alpha-galactsidase A biweekly, and urinary sediments were assessed at 3-month intervals.

RESULTS

The morphologic and immunohistochemical changes in urinary sediment at 6 and 18 months suggested that accumulations of glycosphingolipids in renal tissues were cleared by enzyme replacement.

CONCLUSION

Examination of urinary sediments could serve as noninvasive monitoring of the effect of therapy in patients with Fabry disease.

Non-invasive screening method for Fabry disease by measuring globotriaosylceramide in whole urine samples using tandem mass spectrometry

Fabry disease is an X-linked sphingolipidosis due to a deficiency of alpha-galactosidase A, which leads to the accumulation of globotriaosylceramide (GL-3) in several organs. When recombinant human alpha-galactosidase A is intravenously administered repeatedly before the patient develops permanent tissue damage, there is evidence that the accumulation of GL-3 is decreased in some organs and that the clinical symptoms are alleviated in some patients. However, Fabry disease is rare and many patients are not diagnosed until adulthood after irreversible tissue damage has occurred. Our group has developed a simple and non-invasive screening method for Fabry disease that measures total GL-3 in whole urine samples by tandem mass spectrometry. Using this method, we found that the concentration of GL-3 in whole urine sample from hemizygous patients, including pre-symptomatic young children with classic type Fabry disease, was significantly higher than that in controls. The mean concentration of GL-3 in urine from heterozygotes with symptoms was significantly higher than control concentrations, but GL-3 levels in the urine from 2 out of 8 heterozygotes of classic type Fabry disease were within control levels. An asymptomatic 14-year old hemizygote in the family of a cardiac variant did not have elevated urinary GL-3. Therefore, screening for the classic type and probably renal variant of Fabry disease is possible by measuring urinary GL-3, using our method. The early diagnosis of cardiac variant hemizygotes and some heterozygotes with all types of Fabry disease will not be possible using our method. We propose that this procedure can be used as a reliable, non-invasive, simple method for general and high-risk population screening for hemizygotic patients with the classic type and probably renal variant of Fabry disease.

Fast fingerprinting by MALDI-TOF mass spectrometry of urinary sediment glycosphingolipids in Fabry disease

Fabry disease (FD) is an X-linked inborn error of glycosphingolipid (GSL) metabolism, caused by a deficiency of the lysosomal alpha-galactosidase A, which results in high levels in lysosomes and biological fluids of globotriaosylceramide (Gb3) and digalactosylceramide (Ga2), also known as galabiosylceramide. We report here a detailed study of the molecular species of GSLs in urinary samples obtained from hemizygous and heterozygous patients by use of matrix-assisted laser desorption ionisation and tandem mass spectrometry (MALDI-MS-MS). Twenty-two and fifteen molecular species were identified in the globotriaosylceramide and digalabiosylceramide series, respectively. The major sphingoid base was sphingosine (d18:1), and dihydrosphingosine (C18:0) and sphingadienine (d18:2) were also present. The molecular profiles obtained by MALDI-TOF-MS enabled us to show significant differences between GSLs composition for young, adult or atypic hemizygote and heterozygote patients. Thus, MALDI-TOF-MS and MS-MS proved a powerful tool for screening a population of patients with clinical signs suggestive of FD by direct and rapid GSL fingerprinting and identification, and for study of the biological processes occurring in glycosphingolipid accumulation.

Is globotriaosylceramide a useful biomarker in Fabry disease?

AIM

The aim of this study was to determine whether globotriaosylceramide (Gb3) is a useful biomarker in Fabry disease.

METHODS

The levels of Gb3 were measured in plasma and urine by tandem mass spectrometry in untreated hemizygotes and heterozygotes with Fabry disease and in healthy controls, and the levels were monitored in patients on treatment with enzyme replacement therapy (ERT).

RESULTS

Hemizygotes with classic Fabry disease showed elevated levels of Gb3 in both plasma and urine and could readily be distinguished from normal controls. Male patients with the N215S mutation had normal levels in their plasma but 50% had marginally elevated levels in their urine. Thirty-three percent of proven heterozygotes had elevated Gb3 concentrations in plasma but 97% of those without the N215S mutation (36/37) had an elevated level in urine. The four heterozygotes with the N215S mutation had normal Gb3 levels in urine. The level of Gb3 in plasma initially fell following the start of ERT in all patients who had an elevated level before treatment. However, in a few patients the level subsequently rose. Similar results were found for the levels of Gb3 in urine.

CONCLUSION

Gb3 is not an ideal marker of Fabry disease or the response to treatment in all patients. Plasma and urine levels of Gb3 cannot be used as a marker of Fabry disease in patients with the N215S mutation and many heterozygotes do not have elevated Gb3 levels in plasma. The urine concentration is more informative in heterozygotes and can be used as a measure of the response to therapy. The fall in Gb3 levels in patients receiving ERT was not sustained in some patients, despite a clinical improvement. Additionally, Gb3 cannot be used to monitor the response to treatment in patients who initially have normal plasma and urine concentrations of this glycolipid.

Urinary lipid profiling for the identification of fabry hemizygotes and heterozygotes

BACKGROUND

Fabry disease is an X-linked lysosomal storage disorder resulting from a deficiency of the lysosomal hydrolase, alpha-galactosidase, for which enzyme replacement therapy is now available. In this study, we aimed to identify Fabry heterozygotes not only for genetic counseling of families but because it is becoming increasingly obvious that many heterozygous (carrier) females are symptomatic and should be considered for treatment.

METHODS

We measured 29 individual lipid species, including ceramide, glucosylceramide, lactosylceramide, and ceramide trihexoside, in urine samples from Fabry hemizygotes and heterozygotes and from control individuals by electrospray ionization tandem mass spectrometry. Individual analyte species and analyte ratios were analyzed for their ability to differentiate the control and patient groups.

RESULTS

The Fabry hemizygotes had increased concentrations of the substrate for the deficient enzyme, ceramide trihexoside, as well as lactosylceramide and ceramide, along with decreased concentrations of both glucosylceramide and sphingomyelin. Ratios of these analytes improved differentiation between the control and Fabry groups, with the Fabry heterozygotes generally falling between the Fabry hemizygotes and the control group.

CONCLUSIONS

These lipid profiles hold particular promise for the identification of Fabry individuals, may aid in the prediction of phenotype, and are potentially useful for the monitoring of therapy in patients receiving enzyme replacement.

Optimisation of the separation of four major neutral glycosphingolipids: application to a rapid and simple detection of urinary globotriaosylceramide in Fabry disease

A simple method for the separation of the four major neutral glycosphingolipids, present in all human tissue, was developed. This gradient normal phase-HPLC method utilises a polyvinyl alcohol bonded stationary phase and an evaporative light-scattering detection (ELSD). Screening pure solvents in a binary gradient elution mode allowed, in a first step, to assess the behaviour of the studied solutes and to select the solvents for further mobile phase optimisation. The proportion of the remaining solvents was defined to reach a maximal resolution. The reduction of the analysis time and the enhancement of the signal were obtained by optimising the gradient slope and the flow-rate. Optimal levels of triethylamine and formic acid (TEA-FA) for the enhancement of the evaporative light scattering detector response were established at 0.1% (v/v). Thus, the optimal conditions for the separation of the four glycosphingolipids was obtained with a gradient elution from a 100% chloroform to a 100% acetone:methanol (90:10 (v/v)) mobile phase at 0.2 ml min-1, using a 10% min-1 gradient slope. Finally, this method was applied to detect the excess of one of the neutral sphingolipids, namely globotriaosylceramide (Gb3) in the urine of patients affected with Fabry disease. A liquid-liquid extraction of the sediments obtained from an aliquot of only ten ml of urine proved sufficient to detect the excess of Gb3 present in both hemizygote and heterozygote patients. In all, the ability of our method to detect abnormal amounts of Gb3 in urinary sediments could allow the diagnosis of weakly symptomatic Fabry patients in large screening programs

Measurement of urinary CDH and CTH by tandem mass spectrometry in patients hemizygous and heterozygous for Fabry disease

Fabry disease is an X-linked disorder of glycosphingolipid metabolism resulting from a deficiency of the lysosomal enzyme alpha-galactosidase A. This deficiency leads to the progressive accumulation, in lysosomes of visceral tissues and in body fluids of hemizygotes, of the glycosphingolipids globotriaosylceramide (CTH, Gb(3) or GL-3) and galabiosylceramide (CDH) and to a lesser extent the blood group AB and B related glycolipids. Elevated levels of the glycosphingolipids are found in the urine of hemizygous males with the classic phenotype, but it is not known whether all symptomatic or asymptomatic heterozygotes have elevated levels. We have therefore measured CTH and CDH quantitatively in a multiplex assay using tandem mass spectrometry in urine from a large cohort (44) of genetically proven or obligate heterozygotes including four with the N215S mutation, from classic hemizygotes (28), from cardiac variant hemizygotes with the N215S mutation (6) and from normal controls. The levels of CTH and CDH were related to both creatinine and sphingomyelin. Urinary CTH was elevated in all 28 classic hemizygotes but only in 4/6 of the cardiac variants. The level was within or just above the normal reference range in the four individuals heterozygous for the N215S mutation but was elevated in 38/40 of the other heterozygotes. Similar results were obtained for CDH, except that only 34/40 heterozygotes had an elevated level. The level of CDH was not elevated in the four heterozygotes and 4/6 of the hemizygotes for the N215S mutation. Combining the levels of CTH and CDH did not improve the discrimination of heterozygotes from controls. The ratio of CDH to CTH was higher in heterozygotes than in hemizygotes. Measurement of urinary CTH gave the best discrimination of heterozygotes from controls.

Angiokeratoma corporis diffusum in a Spanish patient with aspartylglucosaminuria

Angiokeratoma corporis diffusum (ACD), initially considered to be synonymous with Fabry's disease, represents a well-known cutaneous marker of some other lysosomal enzyme disorders. Aspartylglucosaminuria (AGU) is a rare hereditary disorder mostly affecting the Finnish population, with only a few sporadic patients of non-Finnish origin. To date, only three patients with AGU have been reported with cutaneous lesions of ACD. A 19-year-old Spanish woman presented with a 10-year history of progressive ACD affecting the limbs, buttocks and trunk. After the age of 6 years she had developed progressive mental deterioration, coarse facies and macroglossia with a scrotal appearance. Peripheral blood smears showed many vacuolated lymphocytes. Enzyme analysis in cultured fibroblasts revealed a decreased activity of aspartylglucosaminidase. By the age of 31 years the patient had developed a bipolar psychosis, polycystic ovarian disease and severe impairment of cognitive skills. This is the first case of AGU detected in a Spanish patient presenting with cutaneous lesions of ACD. To our knowledge, macroglossia with a scrotal appearance and polycystic ovarian disease have not been reported in previous cases of AGU.

Rapid quantitation of globotriaosylceramide in human plasma and urine: a potential application for monitoring enzyme replacement therapy in Anderson-Fabry disease

A method for measuring globotriaosylceramide (Gb3, or GL3) levels in plasma and urine of humans affected by Anderson-Fabry disease has been developed. The analyses are performed using flow injection analysis-electrospray ionization-tandem mass spectrometry (FIA-ESI-MS/MS). The method is rapid, sensitive and hence suitable for high-throughput analyses, requiring only a simple 50-fold dilution for the preparation of plasma and urine samples. The detection of the analytes of interest was achieved using a triple quadrupole instrument operating in the multiple reaction monitoring mode. The linearity of the calibration standard responses, the intra- and inter-assay precision, the accuracy and the detection limit of the method were evaluated. The proposed method allows a rapid and accurate assessment of globotriaosylceramide in biological samples. Data obtained from healthy volunteers and Anderson-Fabry affected subjects suggest a potential role for this technique in monitoring the effectiveness of Anderson-Fabry disease therapy. The results obtained in two actual cases treated with enzyme replacement therapy are reported and discussed.

Determination of urinary sulfatides and other lipids by combination of reversed-phase and thin-layer chromatographies

A fast and simple method for determination of sulfatides in the urine of patients with metachromatic leukodystrophy (MLD, arylsulfatase A deficiency) has been developed. The procedure consists of two steps: extraction of total urinary lipids by reversed-phase chromatography and their HPTLC separation. Two types of sorbents based on different matrixes were compared, of which the hydroxyethyl methacrylate C-18 type sorbent was found to be superior. Twenty-milliliter aliquots of urine are sufficient for the analysis. The technique is appropriate for simultaneous qualitative identification and semiquantitative densitometric determination and is suitable for routine work. The amount of sulfatides is expressed in relation to sphingomyelin, which copurifies with sulfatides and better reflects the level of membrane lipids in urine than commonly used parameters (creatinine, urine volume, etc.). The ranges were found to be 0.15-0.68 nmol sulfatide/nmol sphingomyelin for control individuals and 3.5-27.2 nmol sulfatide/nmol sphingomyelin for MLD patients. The excretion of sulfatides is pathonognomic for true MLD (due to the accumulation in kidney) and therefore its analysis is important for evaluation of suspected MLD cases including clinically and enzymatically atypical cases. The method is also useful as a complementary analysis for other lipidoses with high excretion of sphingolipids in urine (e.g., Fabry disease).

Urinary excretion of the vitronectin receptor (integrin alpha V beta 3) in patients with Fabry disease

A renal disorder is one of the important manifestations of Fabry disease, but the details of the pathogenesis have not been clarified yet. We examined the possibility that the vitronectin receptor (VNR, integrin alpha V beta 3), one of the integrins, is involved in the progression of the renal injury in Fabry disease. We measured the urinary excretion of beta 3 originating from VNR in Fabry patients by immunoblotting analysis and enzyme-linked immunosorbent assay (ELISA). Immunofluorescent microscopic analyses for VNR and globotriaosylceramide were performed on urinary sediments from Fabry patients. Furthermore, beta 3 and vitronectin in kidney tissues were analyzed immunohistochemically. Immunoblotting analysis and ELISA showed that the urinary excretion of beta 3 originating from VNR was significantly increased in the Fabry group compared with both the pathological and healthy control groups. Immunofluorescent microscopy revealed the expression of VNR and accumulation of globotriaosylceramide in urinary sediments from the Fabry patients. Increased expression of beta 3 was observed in glomerular epithelial cells, and in Bowman's capsular epithelial layer and tubular cells, and the amount of vitronectin was moderately increased in the kidney tissues from the Fabry patients. The urinary excretion of VNR was increased, and the expression of VNR was observed in Fabry kidney tissues. The expression of VNR may be involved in the progression of the renal injury in this disease.

Blood group B glycosphingolipids in alpha-galactosidase deficiency (Fabry disease): influence of secretor status

Defect in degradation of blood group B-immunoactive glycosphingolipids in Fabry disease (deficiency of lysosomal alpha-galactosidase EC 3.2.1.22) has been studied using highly sensitive and specific TLC-immunostaining analysis of urinary sediments and tonsillar tissues of blood group B patients and healthy controls, secretors and nonsecretors. The B glycolipid antigens with hexasaccharide chains were consistently found increased (25- to 100-fold) in the urinary sediments of three Fabry patients, blood group B or AB secretors. Conversely, they were absent in the urinary sediment of one blood group B nonsecretor patient. In normal secretors, B glycosphingolipids were present only in traces. Moreover, significant increase in B glycolipid antigens (8-fold) was found in the tonsillar tissue of a Fabry patient blood group B secretor. We conclude that the secretor status is responsible for increased concentration of blood group B glycosphingolipids in both urinary cells and tonsils in alpha-galactosidase deficiency. The quantity of stored B-immunoactive glycosphingolipids, however, is much lower than that of the mainly accumulated glycosphingolipid Gb(3)Cer. The results clearly indicate that active or silent Se gene, which controls synthesis of B-antigen precursors, is responsible for notable difference in B-glycosphingolipids expression in Fabry patients - secretors and nonsecretors. Whether this novel aspect may be of prognostic significance, remains to be established.

Atypical Fabry's disease. An oligosymptomatic variant

Fabry's disease is a rare, inherited, X-linked metabolic storage disease with ceramide hexoside due to alpha-galactosidase A deficiency. Patients with typical Fabry's disease usually present with several clinical manifestations of corneal dystrophy, neurologic abnormalities, cardiovascular disease, heavy proteinuria, and characteristic cutaneous angiokeratoma. However, atypical Fabry's disease with oligosymptomatic phenotype presents with symptoms restricted solely to cardiocytes or kidney and might be diagnosed by chance during a routine endomyocardial or renal biopsy examination. In this article, we report a case of Fabry's disease incidentally diagnosed in a 34-year-old man who presented with intermittent trace or 1(+) proteinuria only. This patient had no history of renal disease in any other family member. A renal biopsy to evaluate trace proteinuria revealed histologic and ultrastructural findings compatible with Fabry's disease. Subsequent to the renal biopsy, a skin biopsy on a few initially unrecognized, scattered, dark-pinkish scrotal papules showed typical angiokeratoma. A biochemical enzymatic assay of alpha-galactosidase in urine and plasma revealed a markedly decreased enzyme level in the hemizygous range.

Lysosomal alpha-N-acetylgalactosaminidase deficiency, the enzymatic defect in angiokeratoma corporis diffusum with glycopeptiduria

Recently a novel case of angiokeratoma corporis diffusum with glycoaminoaciduria was described in a 46-yr-old Japanese woman. Known causes of the cutaneous manifestation were eliminated by enzyme analyses, and further characterization of the accumulated urinary O-linked sialopeptides revealed identity to those excreted by patients with an infantile neuroaxonal dystrophy due to lysosomal alpha-N-acetylgalactosaminidase deficiency. Investigation of the alpha-N-acetylgalactosaminidase activity and protein in the proband revealed less than 2% of normal activity and the absence of detectable immunoreactive enzyme protein, findings comparable to those in the patients with infantile neuroaxonal dystrophy and alpha-N-acetylgalactosaminidase deficiency. In addition, the proband's unaffected offspring had half-normal levels of alpha-N-acetylgalactosaminidase activity, consistent with this enzymatic deficiency being the primary metabolic defect in this autosomal recessive trait. Ultrastructural examination of skin and blood cells from the adult proband revealed the presence of prominent lysosomal inclusions containing diffuse amorphous and filamentous material. In contrast, these morphologic findings were not observed in the nonneural tissues from patients with infantile neuroaxonal dystrophy and alpha-N-acetylgalactosaminidase deficiency. These studies document the occurrence of two forms of alpha-N-acetylgalactosaminidase deficiency and sialopeptiduria, a severe infantile-onset form of neuroaxonal dystrophy without angiokeratoma or visceral lysosomal inclusions and an adult-onset form characterized by angiokeratoma, extensive lysosomal accumulation of sialoglycopeptides and the absence of detectable neurologic involvement.

Effect of acid-base changes on urinary hydrolases in Fabry's disease after renal transplantation

Fabry's disease, which is characterized by alpha-galactosidase A (AG) deficiency, causes early renal failure. Kidney transplants do not reliably supply the deficient enzyme. To assess both urinary excretion of AG by the transplant and the relationship between urine and serum hydrolase activity, acute and chronic acid-base studies were performed in normal control subjects and in the patient with Fabry's disease who had undergone renal transplantation. For the acute studies, alkalosis was induced by intravenous infusion of sodium bicarbonate and acidosis was induced by ingestion of ammonium chloride. The chronic study involved long-term ingestion of NH4Cl by only the patient with Fabry's disease. The results show that AG is secreted by the renal graft. Urinary hydrolase excretion was increased by acute alkalinization and decreased by acute acidification. Acute, but not chronic, acidification increased the patient's serum AG activity, indicating that long-term acidification is not useful for treating Fabry's disease after transplantation. The large changes in hydrolyase excretion induced by acute and chronic acid-base changes show the difficulty of using lysosomal enzymuria as a diagnostic marker for renal disorders without knowledge of acid-base conditions.

Urinary neutral glycosphingolipid analysis of patients with Fabry's disease; rapid isocratic elution from high-performance liquid chromatography as per-o-benzoyl derivatives

Neutral glycosphingolipids from urinary sediments of six patients with Fabry's disease and 11 members of the family of one propositus were analyzed using high-performance liquid chromatography. Per-o-benzoyl derivatives of GlcCer, LacCer, GbOse3Cer and GbOse4Cer were clearly resolved by a solvent mixture of hexane/dioxane/isopropanol (75:25:1, v/v) on a normal-phase silica column. Using our isocratic solvent system, the analysis was completed within 15 min. The smallest amount of glycolipid that could be detected by HPLC was 50 pmol and a linear response was shown at 230 nm up to 400 pmol. The calculated peak area of GbOse4Cer was higher than those of GlcCer, LacCer and GbOse3Cer. The molar ratios of GbOse3Cer to monohexosyl ceramide (CMH) in the urinary sediments were: Fabry hemizygotes, 36.33 +/- 25.54 (n = 6); heterozygotes, 0.94 +/- 0.50 (n = 4); and controls, 0.11 +/- 0.06 (n = 5). The molar ratio CDH/CMH was also higher in patients (8.42 +/- 6.23) than in controls (0.77 +/- 0.23). The female H was a rare example of a carrier with typical clinical manifestations. From the urinary sediment analysis, females E, G and J were suspected to be Fabry heterozygotes, although no clinical signs were observed at the time of examination.

Novel lysosomal glycoaminoacid storage disease with angiokeratoma corporis diffusum

A 46-year-old Japanese woman had disseminated angiokeratoma, confirmed by electron microscopy which showed numerous cytoplasmic vacuoles in cells of the kidney and skin. Enzyme activities against synthetic and natural substrates in leucocytes and fibroblasts were normal. Her urine contained a large amount of sialylglycoaminoacids, with predominant excretion of an O-glycoside-linked glycoaminoacid.