UMLS:C0033687 - FACTA Search

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Query: UMLS:C0033687 (proteinuria)
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Fabry disease, an X-linked lysosomal storage disease, results from the deficient activity of the enzyme alpha-galactosidase A (alpha-Gal A) and the progressive accumulation of globotriaosylceramide (GL-3) and related glycosphingolipids. In classically affected males with this inherited nephropathy, early and marked GL-3 deposition in the podocytes leads to proteinuria in childhood or adolescence. With increasing age, GL-3 deposition in renal microvascular endothelial cells, and to a lesser extent in interstitial and mesangial cells, leads to renal insufficiency in the third to fifth decades of life. Recently identified "renal variants" who lack the classical disease manifestations of acroparesthesias, angiokeratoma, hypohidrosis, and characteristic corneal/lenticular opacities also develop renal failure. In contrast, "cardiac variants" who also lack the classical phenotype, develop proteinuria in adulthood, but survive a normal lifespan without developing renal failure. Here, we review the renal involvement and pathology in the classical, renal and cardiac variant phenotypes, and present highlights of the preclinical studies and clinical trials that demonstrated the safety and effectiveness of recombinant alpha-Gal A replacement for this inherited nephropathy.
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PMID:Enzyme replacement therapy for Fabry disease, an inherited nephropathy. 1183 97

Recent genetic studies indicate that Alport syndrome and thin glomerular basement membrane disease (TMD) may both be due to COL4A3, COL4A4, and COL4A5 mutations, but there is continuing uncertainty concerning the diagnosis and management of patients without classic family history and symptoms. We examined kidney pathology and collagen alpha 3 to alpha 5(IV) expression in a series of 16 patients who presented with overlapping signs between TMD and Alport nephritis. All patients presented with hematuria, and 11 also had proteinuria, of whom 5 had nephrotic range proteinuria. Only 9 had family history of hematuria. In 9 of 16 (60%) we found premature glomerulosclerosis in the renal biopsies. Three of 16 had predominantly wide, lamellated glomerullar basement membranes (GBM), and in these, alpha 3 to alpha 5(IV) was absent in glomeruli or skin, diagnostic of Alport nephritis. One patient (12) had a very wide GBM with intramembranous lucencies but no lamellation. Skin biopsy was collagen alpha 5(IV) positive. Nine of 16 patients had predominantly thin GBM by electron microscopy, and 3 had thin and slightly lamellated GBM. Collagen alpha 3 to alpha 5(IV) expression in the kidney or skin biopsy was present in all of the latter 12 patients. Three patients had end-stage renal disease, 7 patients had hypertension, and 1 patient had chronic renal failure. We found that of the 16 patients with presumed TMD, 3 had X-linked Alport nephritis, 2 appeared to have autosomal recessive Alport nephritis, and the remaining patients had either an Alport or a TMD variant. The latter had histologic and/or clinical evidence of progressive renal disease, including premature glomerulosclerosis, hypertension, sustained proteinuria, and either thin or slight GBM lamellation focally, and preserved alpha 3 to alpha 5(IV) expression. These patients have a TMD variant, but an Alport variant with a potentially transmissible severe defect different from benign hematuria cannot be excluded.
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PMID:Histopathology, ultrastructure, and clinical phenotypes in thin glomerular basement membrane disease variants. 1220 17

Chinese Alport syndrome (AS) was analyzed in 44 unrelated patients who were screened for mutations in the COL4A5 gene by polymerase chain reaction (PCR)-single-strand conformation polymorphism analysis or PCR direct sequencing in 30 of the 44 patients. The clinical data showed that all patients had hematuria; 25 of 29 male patients (86%) and 9 of 15 female patients (60%) had proteinuria; 11 of 29 male patients (38%) and 1 of 15 female patients (7%) had nephrotic-level proteinuria; 10 of 21 male patients examined (48%) and 1 of 12 female patients examined (8%) had hearing abnormalities. Renal function remained normal despite hearing abnormalities, and ocular lesions occurred in 10%. Among 30 of 44 patients who had a family history of end-stage renal disease (ESRD), 80% (24/30) belonged to X-linked juvenile kindreds, and 20% (6/30) patients to adult kindreds. Of the 44 patients, 14 did not have a family history of ESRD, while 11 of 14 patients diagnosed with X-linked AS did. DNA analysis revealed four missense mutations, two silent mutations, one substitution, and one in-frame deletion. PCR along with Southern hybridization analysis revealed a large deletion of the paired COL4A5 and COL4A6 genes. Chinese AS patients were characterized clinically with hematuria, heavy proteinuria, and more juvenile forms. Mutations in these patients were usually small mutations, while a large deletion involving the 5' part of both COL4A5 and COL4A6 genes was identified.
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PMID:Phenotypic and genotypic features of Alport syndrome in Chinese children. 1247 50

Dent's disease, an X-linked tubulopathy secondary to defects in chloride channel CLC-5, is characterised by low molecular weight proteinuria, hypercalciuria, nephrocalcinosis, and renal stones. Mechanisms leading to nephrocalcinosis are unknown. Using a murine collecting duct cell line (mIMCD-3), we confirm endogenous expression of mCLC-5. During transfection of antisense CLC-5, we observe a reduction in CLC-5 protein expression that correlates with a reduction in the number of acidic endosomal compartments, as determined by quantitative analysis of confocal microscope images using LysoTracker Red. Using wheat germ agglutinin-lectin as an endocytic marker, an arrest of endocytosis is observed in antisense CLC-5 treated cells. Exposure of the cell surface to calcium oxalate crystals results in crystal agglomeration in a minority of sense CLC-5 transfectants (45%) and all antisense CLC-5 transfectants. We conclude that expression of CLC-5 in mIMCD-3 cells allows acidification of endosomes and endocytosis, and that disruption of CLC-5 expression causes abnormal crystal agglomeration.
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PMID:Disordered calcium crystal handling in antisense CLC-5-treated collecting duct cells. 1250 84

Mutations in the gene CLCN5 encoding the vesicular chloride channel ClC-5 lead to Dent's disease, an X-linked renal disorder. Dent's disease is characterised by proteinuria, hyperphosphaturia and hypercalciuria, which eventually lead to kidney stones and nephrocalcinosis. As it was unclear how mutations in a chloride channel might cause these symptoms, we and others have generated genetic mouse models to elucidate the underlying pathophysiological mechanisms. We review results obtained from these three mouse models and present new data on endosomal acidification and vitamin D metabolism in ClC-5 knock-out (KO) mice. ClC-5 is expressed in apical endosomes of proximal tubular cells where it co-localizes with endocytosed proteins and the proton ATPase. ClC-5 may provide an electric shunt for the efficient operation of the electrogenic H(+)-ATPase. We confirmed this hypothesis by showing that endosomes from CLCN5 KO mice are acidified at a significantly lower rate than wild-type endosomes. This probably results in the drastic impairment of endocytosis observed in ClC-5 KO mice. Parathyroid hormone (PTH) is filtered into the lumen of the nephron, where it is endocytosed and degraded by proximal tubular cells. The defective endocytosis in ClC-5 KO mice entails an increased luminal concentration of PTH, subsequent stimulation of apical PTH receptors which causes an increased endocytosis of the phosphate transporter NaPi and phosphaturia. We now show that it also results in up-regulation of proximal tubular alpha-hydroxylase that generates the active form of vitamin D from its precursor. We discuss how the primary defect in endocytosis leads via secondary changes in calciotropic hormones to the tertiary symptoms hyperphosphaturia, hypercalciuria and kidney stones.
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PMID:The ClC-5 chloride channel knock-out mouse - an animal model for Dent's disease. 1254 89

Alport syndrome refers to a hereditary disorder characterized by progressive renal disease and a multilaminar appearance to the glomerular basement membrane (GBM). In a small group of patients with Alport syndrome, cyclosporine A was reported to decrease proteinuria and maintain stable renal function over 7 to 10 yr of follow-up. The present study examined the effect of cyclosporine A on GBM structure and the progression to renal failure in a canine model of X-linked Alport syndrome. Affected male dogs and normal male dogs treated with cyclosporine A underwent serial renal biopsies. Body weight, serum concentrations of creatinine and albumin, and GFR were sequentially determined. Controls consisted of untreated dogs that developed end-stage renal failure by 8 mo of age. Renal biopsies were assessed for glomerulosclerosis and the percent of multilaminar GBM as measured by image analysis. Significant differences were found between treated and untreated affected dogs for weight, serum creatinine, and GFR. There was a significant delay in the progression of multilaminar change to the GBM, although treated affected dogs at termination had attained approximately 100% split GBM as did untreated affected dogs. A significant difference in the number of sclerotic glomeruli was also noted; treated dogs rarely developed obsolete glomeruli during the period studied. Interstitial fibrosis was not significantly affected by cyclosporine A treatment. These findings indicate that cyclosporine A is beneficial in slowing, but not stopping, the clinical and pathologic progression of Alport syndrome. At least part of this beneficial effect comes from a delayed deterioration of GBM structure, which in turn may be related to glomerular hemodynamics altered by cyclosporine A.
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PMID:Cyclosporine a slows the progressive renal disease of alport syndrome (X-linked hereditary nephritis): results from a canine model. 1259 5

We describe an 8-year-old boy who presented with steroid-resistant nephrotic syndrome (SRNS) associated with X-linked ichthyosis (XLI). At birth, the patient exhibited scaly skin, cryptorchidism, and steroid sulfatase (STS) deficiency. DNA analysis showed deletion of exons 1-10 of the STS gene. Proteinuria developed at 6 years and was resistant to steroid therapy. Kidney biopsy findings prior to steroid therapy were compatible with minimal change nephrotic syndrome. By immunofluorescence, glomerular basement membranes exhibited diffuse linear staining for the alpha5 chain of collagen IV, making X-linked Alport syndrome an unlikely explanation for the association of SRNS and ichthyosis. Despite immunosuppressive therapy together with oral prednisolone, no clinical response was achieved. He rapidly reached end-stage renal failure and finally underwent renal transplantation. We propose that SRNS should be considered as one of the highly variable phenotypes associated with XLI.
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PMID:End-stage renal failure in a child with X-linked ichthyosis. 1264 29

Fabry disease is an X-linked lysosomal storage disorder that results from a deficiency of the enzyme alpha-galactosidase A (alpha-Gal A). The lack of alpha-Gal A causes an intracellular accumulation of glycosphingolipids, mainly globotriaosyceramide (GL3). Affected organs include, among others, the vascular endothelium, heart, brain, and kidneys, leading to end-stage renal disease (ESRD). Since Fabry disease cannot be cured at present, clinical management is symptomatic. Enzyme replacement therapy (ERT) with recombinant alpha-Gal A has been introduced as a new therapeutic option for the treatment of Fabry patients. Short-term (one year) clinical studies have positively correlated ERT with improvement of clinical symptoms and microvascular endothelial cell clearance. Treatment outcome concerning severe organ manifestations such as proteinuria and renal function impairment, left ventricular hypertrophy, and heart failure in the long run has yet to be shown. In our studies we used sensitive and noninvasive techniques such as ultrasound-based strain rate imaging and magnetic resonance imaging (MRI), combined with MR-spectroscopy (MR-S), for the quantification of functional abnormalities at an early stage of the disease and during long-term follow-up. Future issues should determine the appropriate timing to start therapy and how children and heterozygous females should be managed. Given the diagnostic and therapeutic potential today, it is of importance to identify patients at an early stage and to start therapeutic intervention before progression of organ damage is inevitable.
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PMID:Fabry disease: diagnosis and treatment. 1269 40

Thin basement membrane nephropathy. Thin basement membrane nephropathy (TBMN) is the most common cause of persistent glomerular bleeding in children and adults, and occurs in at least 1% of the population. Most affected individuals have, in addition to the hematuria, minimal proteinuria, normal renal function, a uniformly thinned glomerular basement membrane (GBM) and a family history of hematuria. Their clinical course is usually benign. However, some adults with TBMN have proteinuria >500 mg/day or renal impairment. This is more likely in hospital-based series of biopsied patients than in the uninvestigated, but affected, family members. The cause of renal impairment in TBMN is usually not known, but may be due to secondary focal segmental glomerulosclerosis (FSGS) or immunoglobulin A (IgA) glomerulonephritis, to misdiagnosed IgA disease or X-linked Alport syndrome, or because of coincidental disease. About 40% families with TBMN have hematuria that segregates with the COL4A3/COL4A4 locus, and many COL4A3 and COL4A4 mutations have now been described. These genes are also affected in autosomal-recessive Alport syndrome, and at least some cases of TBMN represent the carrier state for this condition. Families with TBMN in whom hematuria does not segregate with the COL4A3/COL4A4 locus can be explained by de novo mutations, incomplete penetrance of hematuria, coincidental hematuria in family members without COL4A3 or COL4A4 mutations, and by a novel gene locus for TBMN. A renal biopsy is warranted in TBMN only if there are atypical features, or if IgA disease or X-linked Alport syndrome cannot be excluded clinically. In IgA disease, there is usually no family history of hematuria. X-linked Alport syndrome is much less common than TBMN and can often be identified in family members by its typical clinical features (including retinopathy), a lamellated GBM without the collagen alpha3(IV), alpha4(IV), and alpha5(IV) chains, and by gene linkage studies or the demonstration of a COL4A5 mutation. Technical difficulties in the demonstration and interpretation of COL4A3 and COL4A4 mutations mean that mutation detection is not used routinely in the diagnosis of TBMN.
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PMID:Thin basement membrane nephropathy. 1296 34

Alport syndrome (AS) is a type IV collagen hereditary disease characterized by progressive hematuric nephritis, hearing loss, and ocular changes. Mutations in the COL4A5 collagen gene are responsible for the more common X-linked dominant form of the disease characterized by much less severe disease in girls and women. A "European Community Alport Syndrome Concerted Action" (ECASCA) group was established to delineate the Alport syndrome phenotype in each gender and to determine genotype-phenotype correlations in a large number of families. Data concerning 329 families, 250 of them with an X-linked transmission, were collected. Characteristics of heterozygous girls and women belonging to the 195 families with proven COL4A5 mutation are compared with those of hemizygous boys and men. Hematuria was observed in 95% of carriers and consistently absent in the others. Proteinuria, hearing loss, and ocular defects developed in 75%, 28%, and 15%, respectively. The probability of developing end-stage renal disease or deafness before the age of 40 yr was 12% and 10%, respectively, in girls and women versus 90 and 80%, respectively, in boys and men. The risk of progression to end-stage renal disease appears to increase after the age of 60 yr in women. Because of the absence of genotype-phenotype correlation and the large intrafamilial phenotypic heterogeneity, early prognosis of the disease in X-linked Alport syndrome carriers remains moot. Risk factors for developing renal failure have been identified: the occurrence and progressive increase in proteinuria, and the development of a hearing defect.
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PMID:X-linked Alport syndrome: natural history and genotype-phenotype correlations in girls and women belonging to 195 families: a "European Community Alport Syndrome Concerted Action" study. 1451 38

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