Scan Science and Technology
Contact Leading Edge Experts & Companies
The Experts below are selected from a list of 4740 Experts worldwide ranked by ideXlab platform
Norbert Lameire – One of the best experts on this subject based on the ideXlab platform.
Two-tier approach for the detection of Alpha–Galactosidase A deficiency in kidney transplant recipientsNephrology Dialysis Transplantation, 2008Co-Authors: Gert De Schoenmakere, Bruce Poppe, Birgitte Wuyts, Kathleen Claes, David Cassiman, Bart Maes, Dierik Verbeelen, Raymond Vanholder, Dirk R. Kuypers, Norbert LameireAbstract:
BACKGROUND: Anderson-Fabry disease (AFD) is an X-linked condition originating from a deficiency in Alpha–Galactosidase, a lysosomal enzyme. Multi-organ involvement ensues in early adulthood and vital organs are affected: the kidneys, brain, heart. Several reports however suggest that AFD is underdiagnosed. METHODS: We screened a kidney transplant population using a two-tier approach. The first tier was the determination of Alpha–Galactosidase A (AGALA) activity using a dried blood spot on filter paper (DBFP); in the second tier, patients with the lowest Alpha–Galactosidase levels were further subjected to mutation analysis of the GLA gene. RESULTS: From the database of 2328 patients, 1233 subjects met the inclusion criteria. Finally, after informed consent, 673 patients were screened (54.5%-395 women and 278 men). DBFP analysis resulted in a mean AGALA of 2.63 +/- 2.48 micromol/L/h (2.5 and 97.5 percentile were 0.0001 and 5.07 micromol/L/h, respectively). Eleven patients were subjected to further genetic analysis. In a male patient a pathogenic missense mutation p.Ala143Thr (c.427A>G) was identified. CONCLUSIONS: Our results show that the proposed approach can detect AFD patients in a until now seldomly screened high-risk group: kidney transplant patients. We conclude that screening for AFD in high-risk populations is a cost-effective, technically feasible and clinically valuable objective.
two tier approach for the detection of Alpha Galactosidase a deficiency in a predominantly female haemodialysis populationNephrology Dialysis Transplantation, 2007Co-Authors: Wim Terry, Norbert Lameire, Uce Poppe, Irgitte Wuyts, Kathlee Claes, A Maes, Dierik Verbeele, Raymond Vanholde, Koe De Boeck, Anne De PaepeAbstract:
Introduction. Fabry’s disease (AFD) is an X-linked lysosomal storage disease, resulting from a deficiency in Alpha–Galactosidase A (AGALA). Untreated, this leads to precocious failure of vital organ function and death. As enzyme replacement therapy is available, it is of vital importance that affected individuals can be traced. Materials and methods. We set up a screening in the Flemish haemodialysis population using a two-tier approach. The first tier was a determination of AlphaGalactosidase A activity using a dried blood spot on filter paper, in the second tier, patients with the lowest Alpha–Galactosidase levels were further subjected to mutation analysis of the GLA gene. Results. 1284 patients (1047 women, 237 men) were evaluated for inclusion, eliminating patients with definite renal diagnoses. Total 922 patients (71.8 %) were screened (742 women, 180 men). Fifty seven patients were subjected to further genetic analysis. Three GLA mutation carriers were identified: two apparently nonrelated female patients carry the missense mutation p.Ala143Thr (c.427G > A), a missense mutation p.Trp236Arg (c.706T > C) was identified in a man. While the male patient had been clinically diagnosed with AFD, the female patients had remained unrecognized. Additional family based screening resulted in the identification of nine mutation carriers (four males and five females). Discussion. We demonstrated that the prevalence of GLA mutation carriers in our haemodialysis population is 0.3%. Our results show that the proposed approach accurately detects AFD patients. We conclude that screening for AFD in high risk populations is a cost-effective, technically feasible and clinically valuable objective.
Robe J Desnick – One of the best experts on this subject based on the ideXlab platform.
fabry disease twenty two novel mutations in the Alpha Galactosidase a gene and genotype phenotype correlations in severely and mildly affected hemizygotes and heterozygotesJournal of Investigative Medicine, 2000Co-Authors: Patricia Ashtonprolla, Junaid Shabbee, Kenneth H Astri, C M Eng, Robe J DesnickAbstract:
Background Fabry disease, an inborn error of glycosphingolipid catabolism, results from mutations in the X-chromosomal gene encoding the lysosomal exoglycosidase, Alpha–Galactosidase A (Alpha-Gal A; EC 220.127.116.11). The nature of the molecular lesions in the Alpha-Gal A gene in 36 unrelated families was determined in order to provide precise heterozygote detection, prenatal diagnosis, and to define genotype/phenotype correlations. Methods Genomic DNA was isolated from affected males and/or carrier females from 36 unrelated families with Fabry disease. The entire Alpha-Gal A coding region and flanking intronic sequences were analyzed by PCR amplification and solid-phase or cycle sequencing. Markers closely linked to the Alpha-Gal A gene were analyzed to determine if probands with the same mutations were related. Results Twenty-two novel mutations were identified including 10 missense (P40L, W95S, S148N, C172R, M187V, N224S, W226R, A230T, D266H, N320Y), three nonsense (Y134X, C142X, W204X in two families), three splice-site defects (IVS2(+1), IVS3(+1), IVS4(+1)) and six small deletions or insertions (26delA in two families, 672ins37, 774delAC, 833insA, 1139delC, 1188insT). Of the remaining 12 families (33.3%), each had a previously identified mutation, eight of which occurred at CpG dinucleotides including R112C (two families), R112H, R227Q, R227X (three families), and R301Q. Haplotype analysis of the mutant alleles that occurred in two or three presumably unrelated families revealed that the families with the rare novel alleles (W204X and 26delA) were probably related, whereas those with mutations involving CpG dinucleotides (R112C and R227X) were not, the latter being consistent with their origins as independent mutational events. Genotype/phenotype correlations revealed that certain mutations previously found in mild variant patients also were found in classic patients. In addition, the genotypes and spectrum of phenotypic severity were determined in five heterozygotes with no family history. Conclusions These results illustrate the molecular heterogeneity of the lesions causing Fabry disease and emphasize the fact that CpG dinucleotides constitute important hot spots for mutation in the Alpha-Gal A gene. These studies also permit precise heterozygote detection and prenatal diagnosis in these families, and delineate phenotype-genotype correlations in this disease.
twenty novel mutations in the Alpha Galactosidase a gene causing fabry diseaseMolecular Medicine, 1999Co-Authors: Ali K Topaloglu, Christine M. Eng, Junaid Shabbee, Kenneth H Astri, Grace A Ashley, Ingzheng Tong, Robe J DesnickAbstract:
Fabry disease, an X-linked inborn error of glycosphingolipid catabolism, results from the deficient activity of the lysosomal exoglycohydrolase α-Galactosidase A (EC 18.104.22.168; α-Gal A). The nature of the molecular lesions in the α-Gal A gene in 30 unrelated families was determined to provide precise heterozygote detection, prenatal diagnosis, and define genotype-phenotype correlations. Genomic DNA was isolated from affected males and/or carrier females from 30 unrelated families with Fabry disease. The entire α-Gal A coding region and flanking intronic sequences were analyzed by PCR amplification and automated sequencing. Twenty new mutations were identified, each in a single family: C142R, G183D, S235C, W236L, D244H, P259L, M267I, I289F, Q321E, C378Y, C52X, W277X, IVS4+4, IVS6+2, IVS6−1, 35del13, 256del1, 892ins1, 1176del4, and 1188del1. In the remaining 10 unrelated Fabry families, 9 previously reported mutations were detected: M42V, R112C, S148R, D165V, N215S (in 2 families), Q99X, C142X, R227X, and 1072del3. Haplotype analysis using markers closely flanking the α-Gal A gene indicated that the two patients with the N215S lesion were unrelated. The IVS4+4 mutation was a rare intronic splice site mutation that causes Fabry disease. These studies further define the heterogeneity of mutations in the α-Gal A gene causing Fabry disease, permit precise heterozygote detection and prenatal diagnosis, and help delineate phenotype-genotype correlations in this disease.
human Alpha Galactosidase a glycosylation site 3 is essential for enzyme solubilityBiochemical Journal, 1998Co-Authors: Yiannis Ioannou, Ke M Zeidne, Marie E Grace, Robe J DesnickAbstract:
Human Alpha–Galactosidase A (EC 22.214.171.124; Alpha-Gal A) is the homodimeric glycoprotein that hydrolyses the terminal Alpha-galactosyl moieties from glycolipids and glycoproteins. The type, site occupancy and function of the N-linked oligosaccharide chains on this lysosomal hydrolase were determined. Endoglycosidase treatment of the purified recombinant enzyme and mutagenesis studies indicated that three (Asn-139, Asn-192 and Asn-215) of the four potential N-glycosylation consensus sequences were occupied by complex, high-mannose and hybrid-type oligosaccharides respectively. When expressed in COS-1 cells, glycoforms with glycosylation site 1 or 2 obliterated had more than 70% of wild-type activity, and both glycoforms were secreted. In contrast, the glycoform with only site 3 eliminated had decreased activity (less than 40%); little, if any, was secreted. Expressed mutant glycoforms in which site 3 and site 1 or 2 were obliterated had little, if any, intracellular or secreted enzymic activity, and immunofluorescence microscopy revealed that the expressed mutant glycoforms were retained in the endoplasmic reticulum, presumably where they were degraded. Thus glycosylation at site 3 was crucial to the formation of soluble, active enzyme, as well as transport to the lysosome. Absence of the site 3 hybrid-type oligosaccharide exposed an adjacent, normally protected, hydrophobic region, resulting in aggregation of the enzyme polypeptide in the endoplasmic reticulum. In support of this concept, endoglycosidase H-treated enzyme or mannose-terminated enzyme expressed in Autographa californica cells also aggregated when concentrated, emphasizing that site 3 occupancy by a hybrid-type oligosaccharide was required for enzyme solubility.
Robert J. Desnick – One of the best experts on this subject based on the ideXlab platform.
fabry disease an under recognized multisystemic disorder expert recommendations for diagnosis management and enzyme replacement therapyAnnals of Internal Medicine, 2003Co-Authors: Robert J. Desnick, Roscoe O Brady, John A Barranger, Allan J Collins, Dominique P Germain, Martin E Goldman, Gregory A Grabowski, Seymour Packman, William R WilcoxAbstract:
Fabry disease (Alpha–Galactosidase A deficiency) is an X-linked recessive lysosomal storage disorder. Although the disease presents in childhood and culminates in cardiac, cerebrovascular, and end-stage renal disease, diagnosis is often delayed or missed. This paper reviews the key signs and symptoms of Fabry disease and provides expert recommendations for diagnosis, follow-up, medical management, and the use of enzyme replacement therapy. Recommendations are based on reviews of the literature on Fabry disease, results of recent clinical trials, and expertise of the authors, all of whom have extensive clinical experience with Fabry disease and lysosomal storage disorders and represent subspecialties involved in treatment. All males and female carriers affected with Fabry disease should be followed closely, regardless of symptoms or treatment status. Clinical trials have shown that recombinant human Alpha–Galactosidase A replacement therapy–the only disease-specific therapy currently available for Fabry disease–is safe and can reverse substrate storage in the lysosome, the pathophysiologic basis of the disease. Enzyme replacement therapy in all males with Fabry disease (including those with end-stage renal disease) and female carriers with substantial disease manifestations should be initiated as early as possible. Additional experience is needed before more specific recommendations can be made on optimal dosing regimens for reversal; maintenance; and prevention of disease manifestations in affected males, symptomatic carrier females, children, and patients with compromised renal function.
safety and efficacy of recombinant human Alpha Galactosidase a replacement therapy in fabry s diseaseThe New England Journal of Medicine, 2001Co-Authors: Christine M. Eng, William R Wilcox, Dominique P Germain, Nathalie Guffon, Philip J Lee, Steve Waldek, Louis R Caplan, Gabor E Linthorst, Robert J. DesnickAbstract:
Background Fabry’s disease, lysosomal α-Galactosidase A deficiency, results from the progressive accumulation of globotriaosylceramide and related glycosphingolipids. Affected patients have microvascular disease of the kidneys, heart, and brain. Methods We evaluated the safety and effectiveness of recombinant α-Galactosidase A in a multicenter, randomized, placebo-controlled, double-blind study of 58 patients who were treated every 2 weeks for 20 weeks. Thereafter, all patients received recombinant α-Galactosidase A in an open-label extension study. The primary efficacy end point was the percentage of patients in whom renal microvascular endothelial deposits of globotriaosylceramide were cleared (reduced to normal or near-normal levels). We also evaluated the histologic clearance of microvascular endothelial deposits of globotriaosylceramide in the endomyocardium and skin, as well as changes in the level of pain and the quality of life. Results In the double-blind study, 20 of the 29 patients in the recom…
Nature and frequency of mutations in the Alpha–Galactosidase A gene that cause Fabry disease.American journal of human genetics, 1993Co-Authors: Christine M. Eng, L A Resnick-silverman, Dana J.h. Niehaus, Kenneth H. Astrin, Robert J. DesnickAbstract:
Fabry disease, an X-linked inborn error of glycosphingolipid catabolism, results from mutations in the Alpha–Galactosidase A (Alpha-Gal A) gene at Xq22.1. To determine the nature and frequency of the molecular lesions causing the classical and milder-variant Fabry phenotypes, and for precise carrier detection in Fabry families, the Alpha-Gal A transcripts or genomic sequences from unrelated Fabry hemizygotes were analyzed. In patients with the classical phenotype, 18 new mutations were identified: N34S, C56G, W162R, R227Q, R227X, D264V, D266V, S297F, D313Y, G328A, W340X, E398X, IVS2+2, IVS5 delta-2,3, 773 delta 2, 954 delta 5, 1016 delta 11, and 1123 delta 53. Unrelated asymptomatic or mildly affected patients with symptoms confined to the heart had a missense mutation, N215S, that expressed residual enzymatic activity. Related, moderately affected patients with late-onset cardiac and pulmonary manifestations had a small deletion, 1208 delta 3, that predicted the in-frame deletion of arginine 404 near the terminus of the 429 residue enzyme polypeptide. In addition, five small gene rearrangements involving exonic sequences were identified in unrelated classically affected patients. Two small deletions and one small duplication had short direct repeats at their respective breakpoint junctions and presumably resulted from slipped mispairing. A deletion occurred at a potential polymerase Alpha arrest site, while the breakpoints of another deletion occurred at an inverted tetranucleotide repeat. Screening of unrelated Fabry patients with allele-specific oligonucleotides for seven mutations revealed that these were private, with the notable exception of N215S, R227Q, and R227X, which were each found in several unrelated families from different ethnic backgrounds. The CpG dinucleotide at codon 227 was the most common site of mutation, having been altered in 5% of the 148 unrelated Fabry alleles. These studies revealed that most Alpha-Gal A lesions were private, that codon 227 was a mutational hot spot, and that certain mutations predicted a milder disease phenotype.